_

_

-

Th: Authors:

Prolonged Fetal Bradycardla In Psrtudents With And without Epldural Anealhesla

S Persinger, K Rasmus. D Kotetko, R Rotbnan, J Velez, R A&n. C RobeI. W Wright,

J Stone. P Rosen, W Yoshii, D O’Donnell

Afffllatlons: Departments of Anesthesiology and Obsteklcs and Gynecology,

Cedars-Sinai Medical Center, Los Angeles, CA

Introduction: Prolonged decelerations after buptvacatne epidutal anesthesia have been reportedr.s.3 and

retroscactf+ely estimated to xcur in 6.5% of casesa. Uterine hypertonus has teen suggested as a cause of prolonged

de&rations after epidural bupivacatne anesthesia.’ There are IW) published data repotting the incidence of fetal

bradycardtt in patients without epldural anesthesia This study was urhiertakan to detemrine the incfdence of fetal bradycardia prcepecttvdy in a large popuhti of parturtents with and without epidural anesthesia. and, to determine if

there are any predisposing far&s assoctated with fetal bradycardia.

&@g&: Data were mkected durtng an eteven weak period an a non-randomized group of consecutive parturients

(n-973) durtng the first stage of labac. Patttts who requested epidural anesthesia were hydrated with IV fluids and

received a combination of 0.25% buplvacatne (6-10 ml) and fentanyl (103 ug) via epidurat catheter. Complete fetal monitoring and utertna conba+n strips were evaluated in all parturients. The perinatobgist was blinded as to the use

of epaural anesthesia. Fetal bradycardia was defined as FHR less than 120 BPM for 2 minutes or a 46 BPM drop in

baseline for 2 minutes.

&f&t& There was no stgnifiit difference in the indderwe of fetal bradycardtt between Ure epidurat and no-epidural groups (Table I). The groups were similar in regards to age, height, weight and gestational age. Addittonally, there

was no relationship between episodes of fetal bradycardia and timing of epidural anesthetic with placement or

reactivation.

m No-Ecidural (n.259) Eoidurat fn=714) Total (n=973)

tncidence of Fetal Bradycardtt 11 (4.2%) 37 (5%) 48 (4.9%)

Yates cone&d Chi SquanM.163 Prob ~05

Immedtt$ly prior to the onset of fetal bradycardta. the sum of tie peak uterine actttity over the baseline was

significantly higher (p< .02) in the epkiural group (mean measuring 231 mm Hg) versus the noepidural group (mean

measuring 140 mm HG). The sample population (n.973) was further analyzed by subdividing the sample into a no

fetal bradycardia group (n-925) and a fetat bradymrdia group (n-46). There was no statisttcat mrrelatim between

hypotension or use of p&in and the occurrence of fetal bradycardia (pa.5). In patents with fetal bradycardia, the

mean values of gravfdity and parity were significantly lower and the cesarean section rate was signifiilly higher than patients without fetal bradycardta (Table II).

m r&t&y i?x& @Section Rate No Fetal Bradycardia (n=925) mearw2.5 (cl- 1.8) meand. (+I- 1.2) 16.5%

Fetal Bradycardia (n=46) mean4.0 (+/- 1.3) meaM. (+I- 0.9) 41.7%

Probability p-.0036 p-03 p<.oo1

@onelusionS: The overall tnddenca of feta bradycardia in parturtents was 49%. The retattcnship between tie use of

epidurat anesthesia and tetal bradycardta was independent. Atthccgh there was a statisticalty stgnfttt mrretatiin

found between increased uterine tone and the presence of epidural anesthesia, external monitoring and positton

change could account for this difference. Why patients with fetal bradycardia tend to be of lower gravkdity and parity and have significantly hither cesarean seclicn rates requires further study.

Reference?:

1. Abboud, TK. et at: Maternal fetal and neonalal responses after epidural anesthesia with bupivacatne. 2. chloropocaine or lidocaine. Anesth Analg 1962: 6163644.

2. Abbcud, TK, et al: Continuous infusion eptdural analgesia in parturients receiving bupivacaine. chloropnxaine or

lklocafne-maternal. fetal and neonatal effects. Anesti Anatg 1964: 63421.6.

3. Steiger, R, Nageotte, M: Effect of uterine contractility and maternal hypotension on prolonged decelerations after

buptvacaine epidural anesthesia. Am J 06 Gyn 1990: 163806612. _

- a

-

_

._

.-

_

-

_

._

-

.-

-

Tide: THE EFFECT OF EPIDURAL BUPIVACAINE VERSUS INTRAVENOUS NALBUF’HINE ON FETAL HEART RATE DURING LABOR

Authors: mJM.* Chestnut DH, DeBruyn CS

Aff~mtion: Deparaoems of Anesthesia and Obstetrics and Gynecology, University of Iowa College of Medicine. Iowa City, IA 52242

m. Some investigators have alleged dmt cpidmal ancsfixsia results in a high incidence of fetal bradycardia and other feral heart ram (FHR) abnormalities. However, most of these. studies suffer from a lack of randomization to epidural analgesia or alternate analgesic techniques. and they fail to consider the effects of labor itself on the PHR. The purpose of the present prospective, randomized study was to compare the effects of e-piduml bopivacaine and intravenous nalbupbine on FHR during labor.

&&&IQ&. The protocol was approved by the institutional review board. Informed consent was obtained from healthy, nulliparous women with a singleton fetus in vextcx presentation, who requested epidural anesthesia during spontaneous labor at term. Briefly. patients were randomized to receive epidural bupivacaine anesthesia or nalbuphine intravenously between 3 and 5 cm cervical dilation, as defined in an ongoing study of the effect of early epidaral anesthesia on the progress of lab0r.t We reviewed the FHR tracings only from patients who had continuous FHR monitoring during the hour before and after randomization. Tbe investigator who reviewed the FHR tracings was blinded to the group assignment. There were 23 patients in the epidural bupivacaine group and 19 patients in the nalbuphine group. The nalbuphine group received nalbuphine 10 mg intxwenously at randomization. The presence of fetal bradycardia late decelemtions, and variable decelerations was noted. We assessed baseline PHR. short-term and long-term variability, FHFt reactivity, basal uterine tone, number of contractions. and Montcvideo units at frequent intervals. We assessed short-term variability (STV) only in those patients with a feral scalp electrode (n=14). Statistical analysis was by chi square and repeated measures ANOVA as indicated. Pd.05 was considered significant.

&&. There were M differences between groups in baseline FHR. long-term variability, or frequency of variable decelerations across time. Two patients in the bupivacaine group. and four in the nalbuphine group. had a baseline FHR <120 beats/min for >2 minutes during the hoar after randomization (p=NS). No patient in either group had late. decelerations or baseline FHR 590 katsjmin during the hour after mndomizatioo. The percentage of patients wilh reactive PHR tracings after randomization was signiticantly higher in dte bupivacaine group than in the nalbuphine group (RO.01). The percentage of patients with normal short-term PHR variability after randomization also tended to be higher in the bupivacaine group than in rhe nalbuphine group.

z’f % $?*

$ 9 :: je_ R ? ? $?qg@F “‘~~‘&&L~

nlm wv - ,nw I?ISUWQ. This is an ongoing study. The present results suggest that epidural bupivacaine, when

COrnpared to intravenous nalbuphine, is not associated wilh an increase in FHR abnormalities in nulliparous women during labor.

References. 1. Chesmut DH, et al: Abstract, SOAP 1991.

3

_

._

TITLE: Echocardiographic changes during cesarean section AUTHORS: Baratta J, Cziner D, Zakowski M, Kronzon I,

Ramanathan S, Turndorf H AFFILIATION: Dept. Anesthesiology and Cardiology, New York

Univ Medical Ctr, New York NY 10016 INTRODlJCTION: ST-segment changes, chest pain, dyspnea and nausea/vomiting occyt; during cesarean (CS) under lumbar epidural anesthesia. ’ This study assesses if the ECG changes and symptoms were associated with echocardiographic evidence of myocardial wall motion abnormality. NBTHODS: With institutional review board approval, 26 ASA I(E) and II(E) patients for cesarean section were studied. Patients had pre- and post-operative 12 lead ECG, and a QMED cardiac holter monitor (leads II and V5) continuously from 2 hours pre- to 4 hours post-operatively. Patients received epidural anesthesia to a T4 level. Monitoring included blood pressure, holter, and post-op CPK-MB fraction. Transthoracic 2-D echocardiography was performed utilizing a Hewlett-Packard Sonos 1000 unit and 2.5 MHz transducer. Left parasternal long and short axis views were obtained before anesthesia and at T4 sensory level and delivery in all patients. In addition ethos were done whenever ST segment changes, pulse >130 and symptoms occurred. In addition, dummy readings were included to equalize the number of echo studies in all patients. Two blinded cardiologists rated segmentalwallmotion abnormality, ejection fraction, left atria1 and left ventricular sizes. Student's t-test was performed at pcO.05. RESULTS: ST-segment depression occurred in 6 patients (23%), with no wall motion abnormalities. Tachycardia (<130), nausea/vomiting, chest pain occurred 7, 12, 10 times respectively without wall motion abnormality. However, 3 patients (11%) developed septal wall motion abnormalities without ECG changes or symptoms. Left atria1 and left ventricular dimensions were not significantly different between time neriods. Ejection fraction sianificantlv decreased during episodes of results and ECGs were normal. CONCLUBIQN: ST depression occurred in 23% of patients undergoing cesarean section, but was not associated with echocardiographic evidence of myocardial ischemia. However, tachycardia resulted in a decreased ejection fraction. Septal wall motion abnormalities, possibly volume related, occurred in 11% of patients. Reference: 1) Palmer CM et al: Anesth Analg 70:36-43, 1990. 2) McLintic AJ et al: Anesth Analg 74:51-6, 1992.

EJECTION FRACTION

o,l . . . . . . . . . . .._.._.......................... * o.* .._ ..- ___ ____ ~bIllll4 0.4 ..- .-.-. .._

0.1

0

SSLN ST CP NIV P ,130 :1

tachycardia (Fig). All CPK-MB

* = ~~0.05 versus baseline

- 4

-

-

THROMBELASTOGRAPHY FOLLOWING ASPIRIN INGESTION IN PREGNA& AND NON-

PREGNANT SUBJECTS

Orlikowski CEP, Payne AJ*, Moodley J*, Rocke DA

Department of Anesthetics and Obstetrics and Gpaecology’, University of Natal

I~trOdUetiOIl: The safety of regional anesthesia in patients taking antiplatelet drugs remains uncertain. Low dose aspirin has been shown to markedly reduce the incidence of pre-eclampsia and intrauterine growth retardation and increasing numbers of patients on aspirin will present for regional procedures to the anesthetist. At present the bleeding time is recommended as the

screening test prior to regional anesthesia t’) but this test has come under increasing scrutiny as a

predictor of the risk of bleeding in individual patient@. In this study we have evaluated the

thrombelastograph (TEG), a bedside monitor of the viscoelastic changes occurring as blood clots, following a single oral dose of aspirin 6COmg in pregnant and non-pregnant subjects.

Methods: The TEG and bleeding time was undertaken prior to and 6 hours following oral ingestion of 600 mg aspirin in a group of eight volunteers (4 males, 4 females) and in 12 healthy pregnant women (22 - 36 weeks gestation). Bleeding times were determined using a disposable simplate II

device using the modified Iq method. TEG parameters determined included r, k, r + k times and ma. Statistical analysis was by paired two-tailed t test within groups whilst comparison between

groups was by Wilcoxon two sample test.

Results: There were signiticant differences in TEG parameters between the pregnant and non- pregnant groups. The r, k and r + k times were shorter (p < 0.0s) whilst the ma was wider (p = 0.002). changes which reflect the hypercoagulablc state of pregnancy. There was no significant differences in the bleeding time between the two groups. In both non-pregnant and pregnant subjects a single 600 mg dose aspirin significantly prolonged the bleeding time though none was greater than 10 min. In neither group did the ingestion of aspirin signilicantly change any of the measured TEG

parameters.

TABLE I:

PREGIllYT n = 12 Pre - aspirin 7.4 CO.41 2.8 (0.3) 10.1 (0.5) 59.9 (3.3) 4.9 Po*t - aspirin

c.091, 7.8 (1.0) 3.2 (0.7) 11.0 (1.2) 59.4 (4.1)

95% CI -2.2, 2.9 -0.4, 1.3 -1.7, 3.3 -4.3, 3.3 ;:; ';:;I

NOW-PREOYAWT n = 8 Pre . srpirin 9.1 (1.2, 4.4 (1.5) 13.4 (2.1) 50.4 (6.0) Post - aspirin 8.8 (1.1) 4.3 (1.4) 13.0 (2.1) 49.4 (7.4)

"7.2 I;.;;*

95% CI -3.2, 2.6 -2.6, 2.3 -3.7. 2.8 -5.1, 3.2 0:8. 5:3

Conclusion: In this study we were unable to demonstrate any changes in TEG parameters following aspirin despite prolongation of the bleeding time. This is in contrast to Hawkins who demonstrated signilicant prolongation of r and k times following 600 mg aspirin in male volunteerst3’. Differences in methodology may account for the different results. The results of our study question the clinical value of a mild prolongation of the bleeding time following aspirin. The TEG may provide a better overall mcasurc of the adequacy OC in-viva coagulation function. Further studies arc rcquircd to determine whether the TEG can bc used as a screening test prior to regional anesthesia. re3EitEYcES 1. naceonetd R. Editorial 1: Aspirin and extra&ret blocks. Brit J .4naesth 1991; 66: 1-3. 2. Roger* WC et al. A critical reappraisal of the bleeding time. Semin Thr_sis and

Hamstasis 1990: 16: l-20. 3. Haukins RI. Thrwnbelasrography of hunan blood after aspirin. CLinical Pharmacol Therap.

1972; 13: 274-278.

5

-

-.

Ikk: Microcatheter Contlnuous Spinal Analgesia for Labor: Potentlal for Neurologlc Injury wlth 1, 1.5 and 2% Lldocalne

AllttUE: Leicht CH, Vasdev G, Ross BK

Affiliation: Depts of Anesthesiology, Mayo Clinic, Rochester, MN and University of Washington, Seattle, WA

m: Continuous spinal analgesia(CSA) provides some advantages over epidural analgesia for labor and delivery; however, the use of traditional epidural needles and catheters for CSA in laboring patients is associated with a high incidence of post dural puncture headache(PDPH). Several manufacturers(TFX, Kendall, PMP, others) have developed microcatheters for use in CSA in an attempt to decrease the incidence of PDPH. Unfortunately, there have been reports of permanent neurologic sequelae following the use of microcatheters for CSA’. Presently, none of the reports involve CSA for labor but rather, in most cases, have been associated with the use of CSA with 5% lidocaine with dextrose for operative procedures. Microcatheter CSA for labor (with narcotic and lower-dose local anesthetic) is being performed at many centers across the country. To assess the potential for neurologic injury related to the commonly used concentrations of lidocaine administered via microcatheters for labor, we measured lidocaine concentrations along the spinal canal utilizing a spinal canal model and a 289 Co-SpanTM(Kendall) catheter. f&&9&: A spinal canal model was fabricated utilizing cadaver measurements similar to Ross et al*. The model was placed on a stand(modified to allow injections to be performed in a lateral decubitus position and then be immediately rotated to a supine position in a consistent manner) and filled with mock CSF maintained at 37°C. Two injections each of lml of: l%, 1.5% and 2% ‘plain’ lidocaine; and l%, 1.5% and 2% ‘hyperbaric’ lidocaine(with glucose 7- 8%) were made at two different levels in the canal(L2.3, L3-4). We also evaluated two different speeds of injection, the catheter tip direction, and the effect of increased volume Five minutes after injection, samples were obtained at the caudal end of the canal and every 5 ems cephlad for 30 ems; lidocaine concentrations were determined directly using EMIT(enzyme multiplied immunoassay technique), which was validated using “mock’ CSF spiked with known concentrations of lidocaine. &$J&: Detailed results of the concentrations obtained for each sampling level along the spinal canal will be presented. In all cases the addition of glucose shifted the peak concentration from 15 cm from the caudal tip(in the case of the plain solutions) to the caudal tip itself(in the case of the hyperbaric solutions). Lidocaine levels at the caudal tip for l%, 1.5%, and 2% lidocaine with glucose were: 0.14%. 0.25%, and 0.33%, respectively vs. nearly undetectable with the plain solutions. Catheter position had a lesser effect on the distribution and concentration of the plain solutions; whereas, in the case of the glucose containing solutions, the concentration at the caudal tip increased by 2 to 2.5 fold when the catheter tip was pointing caudad. This increase in concentration was nearly negated by increasing the speed of injection, ie., injecting over 20s instead of over 40s. Increasing the volume of the injectate. ie., from Iml to 2ml had little effect on the distribution of either solution other than to approximately double the peak concentrations.

. m: Although we have shown factors such as the addition of glucose, catheter position and rate of injection all influence the caudal concentration of lidocaine, none of the concentrations of lidocaine obtained at any sampling level along the spinal canal model at any time in the study were high enough to be consistent with those known to result in permanent neurologic injury. From this standpoint, it appears that judiciously administered doses(1 to 2 ml) of lidocaine, with or without glucose, via 289 microcatheters for labor should be relativelv safe when the lidocaine concentration is limited to 2% or less. Refere&: 1. Rigler ML, Drasner K, et al: Anesth Analg 72:275-281, 1991 2. Ross BK, Coda B, Heath CH: Regional Anesth. March-April 1992

_

- 6

_

._

_

Title: EFFECT OF CHANGES IN LABOR ANALGESIC PRACTICE ON LABOR OUTCOME

Authors: Naulty JS*. Smith R, Ross R

Affiliation: Departments of Anesthesiology, Nursing. and Obstetrics, George Washington University Medical Center Washington, DC

Introduction: There is conflicting evidence whether epidural analgesia during labor increases the duration of the second stage and the incidence of instramental and cesarean deliveries. Under normal circumstances, it is difficult to randomize or control studies of these effects of analgesia on the outcome and process of labor and delivery. If,however. an alteration in technique is innoduced into a steady state system over a short period of time, it is possible to we “catastrophe” theory and statistical methods to infer the effects on outcome of the change, or “perturbation”. We have therefore examined a steady-state system (a labor floor. with an unvarying population of nurses and obsterriciaos. practicing under controlled protocols) and observed the effects of several abrupt changes in labor analgesic techniques M&Q&.: The labor records of 5401 patients who were admitted with the expectation of vaginal delivery have been prospectively analyzed. Of these patients. 827 were admitted from October 1 1986 to May 31 1987,prior to the first “perturbation”(grp.1). 1960 were admitted between June 1.1987 and June 30.1989(grp.2), and a further 2614 were admitted from July 1 1990 until December 31, 1991 (grp.3) In group 1. lumbar epidural anesthesia was administered using an initial loading dose of 1.5% lidocaine with epinephrine 1/2OO,ooO to achieve approximately a TlO sensory level, and then maintained until complete dilation with intermittent injections of 1.5% lidocaine or .25-.5% bupivacaine. In 92% of these patienwno further injections were performed from the attainment of complete cervical dilation until delivery. Group 2 had epidural analgesia initiated with 10 ml .25% bapivacaine with 5 pg/ml feotaoyl, and then the block was maintained with a coostam infusion of lo-15 ml/hour of.125-.25% bupivacaine with Zpg/ml fentanyl until delivery. Group 3 had epidural analgesia initiated with 10 ml of .062% bupivacaine with .5pg/ml sufentanil. and maintained with a constant infusion of lo-15 ml/hour of .032% bupivacaine with sufentanil .3pg/ml until delivery. These modifications in epidural technique were the only major variations in practice that occurred during the study period. Results were analyzed for statistical significance using analysis of variance. Results.1” June, 1987, immediately following the first change in technique. there was a significant

increase (p c.01 ) in the percentage of patients receiving epidural analgesia for vaginal delivery (96 of pts. having epidurals) There was a statistically significant decrease in the percentage of patients admitted for labor who eventually underwent cesarean delivery. midforceps rotations. and outlet forceps.(fig.l) Following the second change in technique. there was a further significant decrease in cesruean deliveries in labor and midforceps rotations.

- :(

Discussion. The utilization of “catastrophe” modeling techniques and statistical methods allows us to conclude that changes in epidural technique on one labor and delivery unit were associated with decreased cesarean and forceps deliveries in laboring patients. despite an increase in the number and percentage of patients who received epidural analgesia for vaginal delivery. We conclude from this evidence that increasing the percentage of patients who receive epidural analgesia was not associated with mcreases in operative deliveries. and that continuation of epidural analgesia throughout the second stage of labor was associated with a decreased number of cesarean and forceps deliveries.

-

._

-

-

TITLE Effects of Simulated Maternal Hyperventilation on the Human Uterine Artery in vitro

AUI’HORS: Suresh MS’. Johnson TD. Nelson SH. Steenberg ML

AFPIWATICW Departments of Anesthesia, Baylor College of Medicine. Houston. Texas and University of Texas Medical Branch. Galveston, Texas

PwlPose: The effects of hyperventilation during obstetric anesthesia are controversial.‘l) Maternal hyperventilation end hypocapnia can result in uterine vssoconstictlon, decreased uterine blood flow (UBF) and fetal hypoxia. In a study of mechanically hyperventilated pregnant ewes. Levinson et al.@) found that added CO, did not restore UBF to normal and concluded that positive pressure ventilation decreased venous return and cardiac output thus resulting in decreased UBF. The purpose of this study was to evaluate the effects of hypocapnia. simulating maternal hyperventilation on isolated human uterine arteries.

MEIXODS: Use of uterine arteries from patients undergoing hysterectomy was approved by the Institutional Review Board. Ring sections @mm) of uterine arteries fascending branch) from six nonpregnant patients were mounted in 5 ml-volume chambers perfused with Krebs solution. The arterial rings with 1 gm resting tension were allowed to equilibrate for approximately 1 hour before commencement of the experiment. The rings were oxygenated with a mixture of 5% CO, (PCO, 30-35 mmHg) and 95% 0, for two hours while maintaining I gm tension. In each preparation cumulative concentration effect curves were obtained with norepinephrine (NE) and potassium chloride (KCI) before the gas mixture was changed to 3% CO, (PCO, 20-24 mmHg) and 97% 0,. After SO minutes. the cumulative concentration effect curves with NE and KCl were repeated.

RESULIS: In this tissue a change from 5% to 3% CO, did not alter the baseline tension or the madmum mntraction seen with NE or XCl. In the presence of 3% CO* NE responses at lO_‘-108 M were significantly poteniiated (p < .05). The EC,, for NE was 1.5 x 10-9 M in 5% CO,, and 5.3 x lo-‘M in 3% CO, (p ( .OS). Responses to KCI (3% CO,) were not significantly different from control values (p ‘ .05).

I;& I’;6

7 * I a I ” * . .I . *

UIU *ml-

CONCLUSION: During stressful labor. UBF decreases due to increases in circulating catecholamines. i.e. NE.@’ This in viw, evidence coupled with our in vitro r&u&s during simulated hypocapnis would suggest an augmented contractile response of the uterine artery resulting in decreased UBP. Increased sensitivity to NE during periods of hypocapnia combined with elevated NE levels may significantly alter normal uterine artery contractile respo*.$es.

RlWERENces: 1. Cosmi EV. Shnider SM: Obstebic anesthesia and blood flow. In Anesthesiafor Obstetics

2* ed 1994. 2. Levinson G. et al: Effects of maternal hyperventilation on UBF and fetai oxygenatton and

acid base status. Anesthesiology 40:340-347. 1974. 3. Shnider SM. et al: UBP and plasma NE changes during maternal stress in the pregnant

ewe. Anesthesiologj’ 50:524527. 1979.

9

DOES EPIDURAL ANESTHESIA ALTER UTERINE BLOOD FLOW AND PLASMA RENIN ACTIVITY DURING HEMORRHAGIC HYPOTENSION IN GRAVID EWES?

s Vincent RD, Chestnut DH, McGrath J, Chatterjee P, Adkins B, Poduska D. Debruyn CS Instltutlon: Departments of Anesthesia and Obstetrics and Gynecology, University of Iowa College of Medicine, Iowa City, IA. 5.2242

Introduction: In an earlier study epidural anesthesia worsened uterine blood flow (UBF) and fetal Pa02 and pli during hemorrhage in gravid ewes. 1 In that study each animal was bled 20 mkkg, and maternal mean arterial pressure (MAP) was lower in the ewes who received epidural anesthesia than in the control animals. Greater hypotension in the epidural group caused lower UBF and greater uterine vascular resistance despite sympathetic denervation of the uterus, The purpose of this study was to determine: 1) whether epidural anesthesia alters UBF and fetal acid- base status during hemorrhage in the absence of lower MAP: and 2) whether epidural anesthesia alters plasma renin activity (PRA) during hemorrhagic hypotension in gravid ewes, Methods: The protocol was approved by the Animal Care Committee. Mixed breed ewes were obtained from a commercial breeder at 0.8 of timed gestation. Surgical instrumentation was performed during general anesthesia. Each animal recovered at least 3 d before experimentation, Each experiment was performed with the animal standing (supported by a cloth sling) within an approved transfer cart. The experimental sequence was: 1) T=O min. epidural administration of 0.5% bupivacaine (epidural group) or NS (control group); 2) T=30 min, maternal hemorrhage 0.5 ml/kg/min until maternal MAP had decreased 40% below baseline measurements; and 3) additional blood was withdrawn as required to maintain MAP 40% below baseline for an additional 1 h. The collected maternal blood was reinfused after each experiment. Sixteen experiments were performed in eight animals in random order. Only one experiment was done on each day, w Epidural injection of bupivacaine 18 + 2 ml (mean * SEM) resulted in a median sensory level of T-8 at 30 min in the epidural group. Blood withdrawal necessary to achieve 40% MAP reduction was less in the epidural group than in the control group (326 + 83 ml vs. 1010 k 123 ml). But, the additional blood withdrawal required to maintain MAP at 60% of baseline for 1 h was slightly higher in the epidural group. During the 1 h of 40% MAP reduction, uterine blood flow was slightly higher in the epidural group than in the control group (fig). But fetal Pa02 during hemorrhage was similar in the two groups (fig). Plasma renin activity increased during hemorrhage in both groups (fig). However, the PRA response to hemorrhagic hypotension was attenuated in the epidural group.

100

MAP 60 mun * SEM 6. Fetal Pa02

Insan * SEM

PRA m.m * SEM

0 30 0 30 60 !&cussion: Epidural anesthesia did not worsen UBF during hemorrhage when identical hypotension was achieved and maintained in the two groups by adjusting the volume of blood removed. Rather, modest protection of UBF may have resulted in part from the attenuated PRA response during hemorrhagic hypotension in the epidural group.

1. Vincent et al. Anesthesiology 75:As23.1991 Supported in pan by Biomedical Research Support Grant RR 05372 and NIH Grant GM 40917

- 10

_

TlTL.E: Interaction Between Spinal qAdrenergic and Cholinergic Controls on Blood Pressure Regulation

AUTHORS:

AFFILIATION:

C Tong, M.D.*, JC Eisenach, M.D., JA Williams, M.S.

Department of Anesthesia, Wake Forest University Medical Center, Winston-Salem, North Carolina

Introduction: Clonidine, an %-adrenergic agonist, produces selective spinal analgesia free of respiratory depression observed with opioid analgesics. Hypotension, resulting from inhibition of sympathetic nervous system activity, remains the most concerning side effect of intraspinal clonidine therapy. This study was designed to test the hypothesis that pretreatment with neostigmine, a cholinesterase inhibitor known to stimulate spinal preganglionic sympathetic neurons and enhance local q- adrenergic analgesia, would counterbalance clonidine’s hypotensive action.

MethodS: Following timal Care and Use Committee approval, 14 sheep were anesthetized, an intrathecal (i.t.) catheter inserted into the upper thoracic space, and pulmonary and femoral artery catheters inserted for measurement of cardiac output (CO), right atrial and mean arterial pressure (MAP) and heart rate (HR). After recovery from surgery, animals were divided into 2 groups: one received (i.t.) injection of 1 of 3 doses of neostigmine (100,300, 1000 ,L& or saline followed in 15 min by i.t. clonidine (200 g). The second group received i.t. neostigmine (1000 M), neostigmine + methylatropine (1 mg), or saline followed in Emin by i.t. clonidine. Data were analyzed by 2-way ANOVA, with P c 0.05 significant.

Clonidine decreased MAP by Results: >lO%, due to mild reductions in CO and HR. Clonidine-induced hypotension could be inhibited by pretreatment with neostigmine 75 mm prior to clonidine, but not 15 mm prior to clonidine injection. Methylatropine abolished neostigmine’s reversal of clonidine-induced hypotension (Figure

1).

Discussion: Neostigmine has been shown to augment acetylcholine release in CSF after i.t. clonidine and to augment clonidine’s analgesia. Cholinergic receptors on spinal

, Figure 1:Change in MAP 15 min After Clonidine with Different Pretreatments

,-

-

preganglionic sympathetic neurons excite these cells, and may counterbalance inhibition from spinal clonidine. This study suggests one method to enhance a,- adrenergic agonist induced analgesia while minimizing its cardiovascular depression. Supported in part by grant GM35523 from the National Institutes of Health.

11

Title: Placental Transfer and Disposition of Cocaine in The Pregnant Sheep: Preliminary Report

AllWrS: Morishima HO, Chao CR, Masaoka T, Abe Y, Matsuo M, Jack K, Cooper TB

Afffffatbn: Depts. of Anesthesiology, Obstetrics & Gynecology, and Psychiatry College of Physicians 8 Surgeons, Columbia University, New York, NY 10032

Introduction: It has been documented that a bolus intravenous injection of cocaine to pregnant animals produces maternal and fetal hypertension and reduces uterine blood flow in a dose related fashion, leading to the development of fetal asphyxia. This unstable condition may after the placental transfer and distribution of cocaine in the mother and fetus. The present protocol was designed to study the pharmacokinetics of cocaine in the maternal-fetal unit under a steady state condiion in the chronically catheterized sheep. Flethodg: Seven chronically catheterized pregnant sheep received a bolus dose of cocaine (lmg/kg) followed by a constant intravenous infusion (03mglkglmin) over a period of 90 min. Uterine blood flow (UtBF), maternal and fetal arterial blood pressure (BP) and heart rate were monitored throughout. During and after completion of the infusion, maternal (MA) and fetal (FA) arterial blood samples were withdrawn for determination of cocaine and benzoylecgonine (BE) concentrations, pH and blood gases as well as cholinesterase activity (ChE). Pharmacokinetic analyses hve not been completed at this time. m: Cocaine infusion resulted in an increase in maternal BP accompanied by an approximately 20% decrease in UtBF. FA pH and PO2 also decreased during the infusion. However, none of these changes was statistically significant. At 5 min of the infusion, mean

cocaine plasma concentration in MA was 1,466*609 (SE) r-q/ml.

‘A trace amount of cocaine --o- YY --*- MS appeared in the FA at the end

of the bolus injection to the mother. A steady state of plasma concentrations in both MA and FA was reached at 15 min of the infusion, and remained with a FA/MA ratio of approxi-mately 0.1 until the

*o end of the infusion. BE concen- h*l tration increased steadily,

exceeding cocaine concentration by 60 min of the infusion. Following completion of the infusion, cccaine concentration declined precipitously, while BE remained high. Plasma ChE activity was similar in both MA and FA (21&24 and 21!XWJml, respectively), and remained unchanged throughout.. Q&cussioa: These results demonstrate that cocaine crossed the sheep placenta almost immediately following maternal administration. A steady state of the drug concentration in the MA, as well as between MA and FA was reached within lo-15 min of maternal infusion with a significantly lower FAIMA concentration ratio as compared to those of amide-type local anesthetics. Elimination of cocaine was rapid in both MA and FA. Steadily increasing BE concentration exceeded that of cocaine suggests that the sheep has ability to metabolize cocaine efficiently. Prolonged presence of BE, a potent CNS stimulant, particularly in the fetus, may be a useful tool to confirm recent prenatal exposure to cocaine.

Supported by NIDA Grants ROl DA 07566 and 06648, and NIMH Grant MH CRC 30906

_

- 12

-

_

_

__

Tit,.: THE EFFECT DF ,N,,,AY,NG AN OSSTETRIC ANESTHESIDLOOY SERVICE DN RATE DF CESAREAN SECTION AND RAYE OF FORCEPS DEUVERY

Author: L.RWI. DD

Aff”i.don: D*p*nm*nt of Anufha*i*. Pi-w Hoapit*l, Anui*, CalHomi* 90701

Int,od”ction. oh* *ff*ct of spiduml *na*ths*i* on th* p,og,*** of labor. ,*f* of forcsp* dslivsw. and the incidanca of c***,**n **&on i* difficult to evaluate in th* *sting of * mat”,* epidural *s&c*. peu-bnisnts in I&o, *,* gen*,*lly unwilling to wt ** oont,o~* when *“pedo, pain rdisf i* *wit*bl*. Ths p”,po** of fhi* paps, i* to cornpa,* the ,*t* of o***,**n ssction and fo,c*p* d*Iivsnl befow *nd *ft*, *n apidural sn**fh**i* ssrvios w** impl*msnt*d in * bu*v ob*t*tdc unit.

m. In Juns. 1990. * 24 ho”, in-ho”** ob*t*trio *t‘+a*thesiology **tie* w** *l*rled *t Piones, Ho*piPI. Prior to tti* tima. *n**th**i* for th* ob*totric “nit w** providsd by CRNA’* who w*,* cJIed in from home to perform g*n*,*l *n**th**i* for c**a,san *sction*. No *pid”,a( *“**theai* vu* avsilabl* for ,o”tina labor and vaginal delivery. Dsliwry *tatistica for th* y**, p,*oedin9 ths *ns*th**i* **tics a,* compared with the** for th* fi,*t ye*, of th* *n**th**i* **tic*. Db*t*t,ic **wit** w*,* providsd by the *em* five ob*tctrici*n* for **oh war. A policy to reduoo th* incid*ne* of C-ssctions and *nco”,ag* vaginal birfh aft*, c**a,ssn dalivery WSAC) w** in pl*o* prior to th* first study ysa, and did not change dudnp the *t”dy p*dod. Tha padsnt population we.* *imila,d”dnp sach Yea,. Ths *t*n of th* sn**th**i* **tic* did ooinoids with the “** of * nswly rsmodsled labor *nd d*Iiv*v *“it*. Stati*tical *naIv*is I** by Chi *qua,* t**t.

PERlOD June 1989 - MIlV 1990

Ane*th*si* Covsra9a Gsnsrsl Anssthesia for C-**&on

Total Dslivsriar 1919

Tot*, C-9sctions 529

C-section FM* 27.8%’

Total Vaginal Dalivsriss ,384

EpidurJ for V*gind Dalivery 0 Epidurd R*t* 0

Forceps Deliwry 117

Forceps Rata 8.4%

Vapin*l Sinh aft*, C-Ssction 95 VSAC

VSAC + R*p*at C-Ssotion 23.9%’

‘CHI Squara Tast with Yaw* correction. p < 0.09 con*id*,ed aignific*nt.

,“I” 1990 - ,un* 1991

Full **wio*in-houssobststric *n**th**iolo9”

2073

475

22.9%’ p = o.alO7

1599 504

3l.*%

147

9.2% p * 0.52

113

39.6%’ p = 0.CoO1

Epidural ,*t* for vaginsl dslivev w** 31.8%. Ths inc,**** in us* of spidural anssthssia during th* *econd *ix months of tha anssthssia **tic* did not significantly changs th* incidenca of c***,**n **ction.

TABLE II J”lv - Dscsmber. 1990 Januarv June. 1991

EDidural Ret* 26.6% 37.6% C-Ssction Rats 22.4% 23.9%

Di*c”**ion. In thi* *f”dy. initiation of * 24 ho”, in-ho”** ob*t*trio anssthasiology **tic* w** ***oci*t*d with * dscrsass in th* rats of o***,**” rsctions and no si9nitioa”t chaws in ths ,*,* of for=*,,* d*,i”sry. Altho”gh d*t* “,** not collsctsd for th* rat* of *“oc***f”, “SAC, th* ,*fio of s”cc***f”, VSAC ova, *I, the** ~rassntin~ with p,svio”* C-*action ino,***ed rkgnificantlv with *n *pid”,*l nswics.

Refersncas. 1. Thorp. JA: Ths sffsct of confin”o”* spidural analgsris on c***,**n **cfion for dy*foci* in nulliparous women. Am

J Ob*t*t Gynscol IS,: 670-679. 1999

2. Ssiley.DW: Epidural Analgs*ia and Forcsps dslivsry. Anessthssia 39: 292-9, 1993.

13

-

-

_

-

._

,.-

-

_

_.

-

Pain after Cesarean Section: Does Infiltration of the Wound with a Long-Acting Local Anesthetic decrease Postoperative Narcotic Requirements?

Michael N. Skaredoff MD’. Christine Kassa MW Nancy J. Carlson MO+, Jeffrey Fullenkamp DO’, Reza Ehsan MD’ ‘Department of Anesthesiology, Loyola University Medical Center. Maywood IL 60521 Wmhursl Memwial Hospital, Elmhurst IL 60126 +Department of OBGYN,Loyola University Medical Center, Maywood IL 60521

Introduction: The aims of the present study were to determine 1) whether local anesthesia used during surgery decreases the severity of pain during the immediate postoperative period experienced by parturients having cesarean section and 2) whether IV narcoticrequirements would be decreased.

Methods: This is arandomized double-blind study with approval from the Institutional Review Board for Experimentation on Human Subjects. 40 female patients who were scheduled to have elective cesarean section were divided into two goups. Group I [contols] had spinal anesthesia for the surgical procedure using 0.75% bupivicaine. At closure of the surgical wound up to 30 ml of normal saline was injected into the fascial and subcutaneous tissues. For 48 hours the parturient had a Patient Controlled Analgesia[PCA] device which recorded cumulative morphine doses. The patient also completed a simple questionnaire which included a visual-analog pain scale and also inquired about the patient’s subjective responses to pain, sleep and general satisfaction with her anesthetic care. Group 2 had the same protocol as Group 1 but instead had up to 30 ml of 0.25% bupivicaine injected into the fascial and subcutaneous tissues at would closure. An Unpaired Two Group t-test with a ~~0.05 was used for statistical significance.

Results: The infiltration of bupivicaine at would closure did not significantly influence the use of the PCA device either at 24 hours OT at 48 hours [when most PCA devices were discontinued]. In addition, visual-analog scores were not significantly different in either goup. A check question in the questionnaire regarding overall comfort also should no significant differences. Interestingly enough, the only significant different that appeared was that patients who had the bupivicaine infiltration were able to sleep betler[ p<O.Ol].

Discussion: Kissin et all reported in 1990 that postoperative pain in inguinal herniorraphy can be decreased if the surgery is performed with the addition of local infiltration to general anesthesia. We felt that addition of local infiltration would afford the parturient a significant degee of comfort in the immediate postoperative period. It would appear that when spinal anesthesia is used for cesarean section, little obvious difference is seen. The possible benefit for the pat-turient is that with local infiltration, she is able to sleep better

1. Kissin I, Cozakov C, Ayache M et al: Blockade of nociceptive input during surgery can decrease postoperative pain. Anesth Analg 1990; 7O:S206

The HIV+ Parturient and Regional Anesthesia: Clinical and Immunologic Response SC Hughes. MD, PA Dailey, MD, D Landers.. MD, BJ Dattel, MD. WR Cmmbleholme, MD. JL Johnson

San Francisco General Hospital, University of California San Fran5.w

iotroduction: In January 1992, it was reported that the “second 100,000 cases of AIDS” has occurted in a little over two years vs 8 years for the “first lOO,OOO.“t Heterosexual transmission increased 44% and women represented 12% of the second 100,000. HIV+ partmients will be part of every obstetric suite. There is virtually no information concerning anesthetic choices and risks in this group and cautions against regional and general anesthesia have been expressed. This study was understaken to evaluate the possible problems or risks associated with regional anesthesia in the HIV+ partmient and to determine if its use had any effect on the course of the disease. M,&RQ&: With approval of the Committee on Human Research, we evaluated the obstetric course of 23 HIV+ women. Patients had extensive medical and laboratory evaluation prior to delivery and 6 months postpartum as part of a long term study. The study patients had ante and postpartum Hct, WBC, CD4’s, P24’s and B2 microglobulins drawn. Patients were screened for use of antivirals (AZT) and major infections (PCP, KS, lymphadenopathy) as a potential sign of deterioration in the illness.

The anesthetic management was chosen by the patients and physicians managing the case The anesthetic records (N=15) were then reviewed and compared with me group for which no anesthesia was required (N=8, Control). The records were carefully scrutinized with special attention given to the immediate postpartum period and six months for complications relating to anesthesia. Of particular concern were neurologic problems to include myelopathies, neuropathies, or any CNS changes or infection. The fetal outcome was recorded to include the HIV status of the newborn. a: Of the 15 patients who received anesthesia, there were 14 epidurals and 1 spinal. There were no neurologic or infectious complications or any changes suggesting that regional anesthesia had adverse sequelae. At a six month follow up visit, there were no unique neurologic or motor findings. This was also u-ue of the 8 HIV+ patients with no anesthesia. The laboratory data is shown in Table 1. There were no significant differences at any time interval between the two groups. The CD4 count tended to remain stable in most patients over the six month period and the P24.s SeenEd relatively unchanged, although this data is incomplete. The HIV status of most babies (61.5 vs 71.4%) remained indeterminate (studies pending). I!zble 1. RegjppaLBpeStbesia No_

AZT use 5 5 3 4

kE”- =* pcp 7

&6 0 1

4.8?JJ w

7.4il.5 IlJtL‘4 lLw.4 10..w.,

HE, %.C-L?., Y.6i4.0 ,kEE

CD, 4w ,ISiz4

0 1 3.X‘%?.?,

1 *oL*w

0 11 9 , 5

I eu sw ,+‘,- 5+.4

* 0 314 1’2

* 3 recent drllrrks “o( inchJded

Discussion: As the number of women with AIDS increases, the anesthesiologist must become familiar with their unique medical problems which may affect anesthetic management and choice. While there is a large body of literature concerning anesthesia and immunologic consequences in people with normal immune systems, mere is little or no data in the AIDS population. The potential neurologic complications in patients with AIDS is wide and varied and some may hesitate with regional anesthesia. Vacuolar myelopathy (subacute or chronic) is very common and distal symmetric polyneuropathy affects l/.3 of AIDS patients eventually.

Our clinical experience with many non-obstetric patients and now these focused findings suggest regional anesthesia is not contraindicated. We have had no adverse neurologic outcome or infectious problems. The HIV+ parturients who received anesthesia were no different from the control group (HIV+, no anesthesia) to include CD4 counts or changes in systemic manifestations of their disease. While the study has significant limitations, we believe that with careful medical evaluation and review of routine data, regional anesthesia is an appropriate choice in the HIV+ parturient.

1. The second 100,OCO cases of AIDS; MMIVR, Vol. 41, No. 2, January 17.1992

16

-

-

._

_-

._

.-.

-

,_

.-

ZWIlUW lCurtmm J, Thozp JM Jr, Ferry S, Spielnnn FJ, Peretta S, Cefalo FC,Mueller R

AWILIMICN: EeptsofcbstetricsaniQmcolo9yandIuBthesiology, University of North Camlti, Chapel Hill, IC 27599-7010

imreasd r&k of crvduMlscular cm&cations including cocaine~bygravid~llasbeenassociatedwithan

has been slnwn that isolated papillaty nuscl~ strips fmwF-mA rats pretreat& with pmgestercme exhibit 1 toxicity relative to non-preqant amtmls. whatrma.insImkrKwnis whtherthe cbsemd effect in ~ismdia~byprogestercne alme, or by other steroids associated with pregmlq (specifically estrogen). !che plqxxe of this study is to: 1) cbrmstmte preqmcy-Wteddifferences during axdine expm_ue in the isolated

v&Ether these differemes are

Mettods sixty Sqague-Dawley rats were heguinized and amdhetizd. Theirheartskereexcis&,attachedtn Gmgenhff'S aFparatus, and perfusedwithKrebssolutian.TheleftverRricle~ca~izedardleft ventricular systolic pressure (Lvsp), amtraddity, and heart rate (RR) wxetbnlmsmzd. Afbx 15 minutes of stabilization, ths karts were divicki into me of five gnxpe: 1) ncm-pregnant femle amtrols, 2)

alsOinthlMXl-pE%3IB&~~pretreatedWithestmgenal~Ore!3trogen (p<.O45 for each

SurprisiwY, e.nhr.A denonstratedirlthe

mwxqmlt anltmls. For heart rate, decxwzs~shcwntoaxurin

allgrrup ateach_.

Discussicm: we coKll.& that preqamq ZZEGEicity of amine

exacerbtesthedirect

amI cmtmdility). (asdfnmsixltedby enhanceddecreasesiIlLVSP

wh?reaspmgestercllehasprwiouslybeeninpli.cat.Ed as anediatx of this effect inpapillarymscle strips, estmgen also aF.qmrstomediatehei9htl?nedcocaine perfusedwlnlelwutsareutilized.

cardiac toxicity when isob~

_

19

-

_

_

.

TITLE: Intrathecal Neostigmine Potentiates the Analgesic Effects of Intrathecal Clouidine

AUTHORS:

AFFILIATION:

Dawn J. Detweiler, MD,’ James C. Eisenach, MD

Department of Anesthesia, Wake Forest University Medical Center, Winston-Salem, NC 27157-1009

Introduction: Clonidine administered intraspinally produces analgesia through a post-synaptic, a-2 mechanism in the dorsal horn. Interestingly, studies in rats have demonstrated that the analgesic response to intraspinal clonidine can be attenuated by pretreatment with intrathecal atropine, a muscarinic antagonist. This suggests that analgesia is produced via an intermediary choline@ neuron through the release of acetylcholine. The purpose of our study was to test this hypothesis in sheep.

Methods; After approval by the Animal Care and Use Committee, seven sheep were anesthetized and cervical intrathecal catheters were surgically inserted. Complete recovery and a minimum of 48 h were required prior to initiating any study. Antinociception was measured as withdrawal to a mechanical pressure stimulus to the forelimb. Four separate trials were performed on each sheep at a minimum of 48 h apart. Neostigmine, methylatropine, idazoxan (an a-2 antagonist) or saline were administered intrathecally in a randomized blinded fashion followed by cumulative doses of clonidine with analgesia testing performed 20 min after each dose. The pressure at the time of withdrawal was converted to Newtons and the data expressed as the %Maximum Possible Effect (%MPE) + SEM. Results were analyzed by a two way ANOVA. A P value < 0.05 was considered significant.

Intrathecal clonidine produced Results: 100

dose dependent analgesia as expected. This response was inhibited by

so

pretreatment with idazoxan and w so 1 +NEo~yp$re:tr

potentiated by pretreatment with $ neostigmine. Methylatropine did not 40 /

1 P

affect the antinociception produced by clonidine.

2. t I +IDA

Discussion: These results agree with ’ i;-i’_,-

data in rats and studies showing that 10 30 100 300

clonidine induces acetylcholine release CLONIDINE DOSE @cd

in CSF. Why methylatropine failed to inhibit this response is unclear. It may be due to the fact that methylatropine is very polar and may not have penetrated the spinal cord sufficiently to block the muscarinic receptors in the dorsal horn. The more lipid soluble atropine may have been more effective in antagonizing the analgesic effect of clonidine. This is currently under investigation. The clinical applications of this need to be tested. However, theoretically, small doses of neostigmine could be administered intrathecally to potentiate the analgesic effects and decrease the side effects of intraspinal clonidine.

Supported in part by NIH Grant GM35523

- 20

_

-

-

.-

Tide: TOLERANCE OF CRICOID PRESSURE BY CONSCIOUS VOLUNTEERS

Authors: R G Vamter

Affiliation: Anaesthetic Department, St. Thomas’ Hospital, London SE1 7EH UK

Introdu~ Gastro-esophageal reflux is frequent in pregnancy and regurgitation is normally prevented by the upper esophageal sphincter, except during unconsciousness. Cricoid pressure is the linchpin in the technique to prevent regurgitation of gastric contents during induction of general anesthesia. Because upper esophageal sphincter tone may fall h&,rg loss of consciousness (LOC) with thiopental(l), cricoid pressure should be applied to the awake patient, who may need to tolerate it for about 20 set, the mean time to LOC following a bolus dose of tbiopentai.(l)

&&ho& After ethical approval and informed consent, 22 healthy volunteers, age 26- 42y, lay with head and neck supported on a standard pillow. Cricoid force measured in Newtons (N) was applied to the cricoid cartilage via a shaped foam pad attached to a load cell, starting at SN and increasing in 5N increments up to SON or until it became intolerable. Each level of force was applied for 20 set (if tolerated) followed by a 1 min rest. Symptoms were recorded at each level of force.

Results: The numbers of subjects with symptoms at each level of cricoid force are shown in the figure. Ail subjects tolerated 2SN for 20 set, but at this level all but three described it as uncomfortable. Two subjects felt nauseated, one at 25 and the other at 35N. Between 35 and 45N nine subjects had difficulty breathing and two had complete airway obstruction at 45 and 50N.

Discussion: Cricoid pressure can compensate for a fall in upper esophageal sphincter tone and restore the luminal pressure to above the awake value, but the force required varies and up to 40N may be necessary in some patients(2) Upper esophageal sphinter pressure begins to fail before LOC(l) and a criwid force greater than 20N will be poorly tolerated in the awake patient. Sellick originally recommended moderate pressure initially, increasing to firm pressure at LOC(3) Our findings suggest 20N should be applied when awake, increasing to 4ON at LOC. This can be judged by practising on weighing scales (20N-Zkg).

Reference& l.Vamrer RG, Pryle BJ, O’Dwyer JP, Reynolds F: The reduction in upper esophageal pressure with d-dopental. SOAP abstract

a5

2.Vanner RG, O’Dwyer JP, Pryie BJ, *’ Reynolds F: Upper esophageal 15 pressure and the effect of cricoid pressure. Anaesthesia 1992; 47: 10 in press

5

3.Sellick BA: Cricoid pressure to control regurgitation of stomach contents during induction of general anaestheaia. Lancet 1961; 2: 404-406

Cricoid force (Newtons)

-

- 21

-

-

_

-

-

Title: THE REDUCTION IN UPPER ESOPHAGEAL SPHINCTER PRESSURE WlTH THIOPENTAL

Authors: Vanner RG, Pryle BJ, O’Dwyer JP, Felicity Reynolds

Affiliation: Department of Anaesthetics, St Thomas’s Hospital, London, England.

Introduction: The upper esophageal sphincter is formed mainly by cricopharyngeus, a striated muscle whose tone creates a sphincter pressure which prevents the regurgitation of esophageal contents into the pharynx (Fig. 1). The neuromuscular blocking drug succinyicholine usually causes an abrupt fall in upper esophageal sphincter pressure (UESP) with the onset of fasciculations(1). In those patients at risk of regurgitation cricoid pressure is designed to counteract tbii reduction in UFSP, but there is controversy about whether it should be applied before or after loss of consciousness (LOC). Mean UESP is 40 mmHg when awake and falls during deep sleep. The effects of anesthetic drugs on UESP have not been previously studied in humans. We have recorded UESP during LOC with a rapid intravenous injection of thiopental. UESP was measured continuously by a manometry catheter, the Dent sleeve(Z). M&l!& After informed consent 16 patients, ASA I and II, were premeditated prior to elective surgery with intramuscular papaveretum (mean dose 0.19 mg/kg) with hyoscine. After the catheter was zeroed at the criwid cartilage, it was swallowed via the anesthetized nose, and positioned so that tbe sleeve straddled the sphincter and faced posteriorly. The patient was pre-oxygenated while lying on a standard pillow and the baseline awake UESP was recorded two minutes latex. UESP was recorded continuously by a printer as thiopental4.OmgAcg was injected into a large forearm vein over four seconds and flushed with saline. LOC was timed to the loss of tbe eyelash reflex. UESP was also noted one minute after succinylcholine 1.0 mgkg. The paired t-test was used to assess the significance of a decrease in UESP from the awake value. &&& Mean age was 46(range 33-56) years. Mean time to LOC was 2O(range 16-29) seconds. Figure 3 shows UESP awake and the effect of thiopental in each patient. UESP was (meankSD): awake, 43+ 19 mmHg; at LOC, 26&13 nunFIg; 30 seconds after LOC, 9&7 mmHg; after suxametho&m, 8~5 mmHg. Figure 4 shows that mean UESP started to decrease before LOC and the most rapid fall was in the five seconds before LOC. UESP after succinylcholine was not signiticantly different from that after thiopental @=0.4). Only one patient was drowsy following premeditation and had an unusually low awake UESP of 8.0 nunHg. Discussion; Thiopental causes a rapid fall in UESP which usually starrs before LOC. To counteract this fall in UESP, in patients at risk of regurgitation, criwid pressure should therefore be applied before LOC, as Sellick originally describedO).

Referenca 1. Davies DD. Relaxation of the criwpharyngeal sphincter by suxamethonium. British Journal of Anaesthesia 1963; 35: 219-223. 2. Dent J. A new technique for continuous sphincter pressure measurement. Gastroenterology 1976; 71: 263-267. 3. Sellick BA. Criwid pressure to control regurgitation of stomach contents during induction of anaesthesia. Lancet 1961: 2: 404-406.

Mean UESP fmmHg)

- a2

-

.-

_~~

.,_

_

.-.

_

_

._

._

._

-

-

Title: PHENYLEPHRINE FOR HYPOTENSION IN HIGH RISK PARTURIENTS DURING CESAREAN SECTION

Authors: Zakowski M, Otto T, Baratta J, Ramanathan S, Turndorf H

Affiliation: Dept. of Anesthesiology, New York Univ Med Ctr, New York, NY 10016

Introduction: Phenylephrine (Phen) has been used for treating maternal hypotension in healthy parturients (1). This study evaluates Phen in high risk parturients. Methods: Informed consent and review board approval were obtained. High risk parturients (n=80, diabetes mellitus, severe asthma, twins, preeclampsia) undergoing cesarean section under regional anesthesia were studied. Patients received 1500 ml of Ringer's lactate hydration. Those who developed systolic hypotension (<90 mmHg'or a 30% decrease) were randomized to receive ephedrine 10 mg (Eph, n=25) or Phen 100 pg (n=27). Patients not requiring vasopressor (n=28) served as controls. At delivery, maternal arterial, neonatal umbilical venous (W-) and arterial (UA) blood PO*, PCOz, pH, lactate (L), pyruvate (P), glucose (G) were measured. Neurologic and adaptive capacity (NACS) testing of the infants was performed by an independent observer at 2 and 24 hours after birth. Results (mean +lSE) were analyzed using ANOVA, Kruskal-Wallis, and Wilcoxin signed rank test, p ~0.05. Results: No significant differences occurred in high-risk categories, Apgar scores or birth weight among the groups. No significant differences occurred in baseline, hypotensive and post-therapy blood pressures and heart rate between the Eph and Phen groups. Neither maternal or neonatal acid base status nor other indices of anaerobic metabolism including excess lactate (XL) differed among the groups (Table, Figure). No differences were seen in the NACS scores. Discussion: The use of Phen for treating maternal hypotension

UMBILICAL ARTERY

during cesarean section produces loo . neonatal and maternal outcome

similar to that seen with 10 PHENILEPHMNE ephedrine. No evidence of fetal_ lactic acidosis was seen with 2 , Phen. E References: 32:559,1988

1)Acta Anaesth Stand o.,

0.01 Table

0 L P XL L/P

CONTROL EPHEDRINE PHENYLEPH m PH 7.28r.02 7.28t.01 7.27+.02

PCC* 50f1.7 5ot1.9 53+2

PO2 20f1.2 2021.5 19f1.3 BE -2.8+1 -2.8f.8 -3.Of.8

rrV PH 7.322.01 7.31f.01 7.31r.02 PC02 42k1.1 43t1.3 46+1.4

PO2 3Ot1.2 3121.4 32f1.8 BE -3.3k.8 -4.Ok.8 -3.2f.7

_

-

Thromboelastography and Standard Coagulation Tests in Pre-eclamptic Patients Authors: GR Havnes. PhD. MD, WJ Martin, DO, JD Baker, III, MD, KP Rainwater, MD’, BH Dorman, PhD, MD Departments of Anesthesiology and *Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina

INTRODUCTION: Pre-eclamptic patients frequently have thrombocytopenia with or without other evidence of a consumptive coagulopathy. Acceptable coagulation test criteria for epidural placement in pre-eclampsia are controversial. We report preliminary data on tbromboelastographic (TEG) values pre-eclamptic patients. METHODS: After approval from our Institutional Review Board, we studied coagulation tests in 8 uncomplicated and 8 pre-eclamptic term parturients. Pre- eclamptic patients were identified by blood pressure changes, proteimuia and edema. Women less than 18 years old with fetal distress; pre-existing hypertension; known cardiovascular, pulmonary, hepatic, renal, hematologic, or neurological disease; were excluded. After obtaining informed consent, blood for standard tests (PT, aPTT, ll’, platelets, fibrinogen) as well as for activated clotting time (ACT) and TEG analysis were obtained. Pre-eclamptic patients, before and after magnesium therapy, were compared to normal parturients. The data was analvzed usine the t test. ANOVA, and Pearson’s correlation. A p value

I ”

of < 0.05 was considered significant. Pre-echumxia (n=8)

x +Mrr** 11.7 + 1.3 11.6 + 0.1 31.2 + 2.8 28.2 + 2.4

RESULTS’ Control (n=8) PT (set) 11.9 * 0.5 aPlT (set) 29.0 2 1.1 TT (set) 24.1 + 2.1 Fibrinogen (mg/dl) 498 + 77 Pits. (x103/mm3) 241.8 + 74.3 ACT (set) 118 + 16 r (min) 15+4 r+k(min) 22 + 7 Alpha (degrees) 47+ 11 MA (mm) 76 + 7

A6dm 0.91 + .03

%dM4 Mean + S Do:z f .04 - . ‘I -* PC.05

25.5 + 2.3 415 + 166 246.5 + 105.8 125+17 17+4 27 +. 9 37 + 14 69 + 20 0.95 + .023 0.93 f. .03

22.1 + 0 492 + 52 168 + 96.4 108 + 27 27 +- 23 45 f 40 31 +. 56 + 20* .95 + .07 .92 + .08

Discussion: No differences were observed between groups in the initial coagulation tests. TEGs from normal parturients, appeared qualitatively hypercoagulable, primarily because of increases in the maximal amplitude (MA). The r (reaction) time was prolonged in Mg”-treated pre-eclamptic patients, although the difference was not signiScant. A hypocaguable trend was evident in pre-eclamptic patients (decreaseing alpha angle & MA) that was not apparent by standard coagulation tests. The best correlation of TEG values with standard tests occurred in the Mg”-treated pre-eclamptic group (MA vs PT, r = -.99; MA vs PLT, r = .82; MA vs Fibrinogen, r = .86).

a3

.

TITLE: STORAGE AND REUSE OF NARCOTICS FOR EPIDURAL INJECTION PROMOTES MICROBIAL GROWTH

AUTHORS: &,,&I Newman PhD. MQ SL Young PharmD, J Vazquez MD, R Pate1 MD, & Ivankovich MD

AFFILIATION: Depts of Anesthesiology and Pharmacy, Rush- Presbyterian- St. Luke9 Medical Center, Chicago IL 60616

oducth . While occurring infrequently, epidural (E) or subarachnoid (SA) infection is a dreaded complication. Sufentanil (S) and fentanyl (F) are used in EjSA anesthesia for obstetrics. It is customary to withdraw the contents of an ampule of S into a 1 cc sterile syringe. As needed, the S is added to sterile mixtures of local anesthetics and injected into the SA or E space. For F, the amount required is withdrawn from the 2 cc ampule and the rest sterilely stored in a syringe for subsequent use or return to the pharmacy. It has been demonstrated that narcotics do not have antibacterial properties'. The purpose of the present study was to determine if the S and F are contaminated by this procedure or remain sterile as evidenced by no sign of bacterial growth. Methods: In the time period 4/20/91 to S/3./91, 49 S and 12 F syringes were cultured for the presence of bacteria or fungi growth. The anesthesia personnel were unaware a study was being conducted on their returned syringes. Upon return to the pharmacy the syringes were emptied and flushed with 0.2 ml of sterile normal saline. Aliquots of O.lml were plated onto a blood agar plate for bacterial growth assessment and onto a Sabhi plate to assess the growth of fungi. The plates were sent to the hospital microbiology laboratory for culture and identification. Results: Of the forty-nine S syringes tested, two were positive for staphylococcus, one was positive for staphylococcus and gram positive rods, and one was positive for aspergillus. This was an 8.2% (4149) rate of contamination. Of the twelve F syringes tested, one was positive for staphylococcus for an 8.3% contamination rate. During this time period there were no cases of SA or E infective processes in any parturient. Discussion: Contamination of the F and S did occur. It is not known if the contamination originated from: a glass particle from the neck of the ampule that fell when first opened', a break in sterile technique, or a contaminant during the plating out process. In any case, the following is recommended: (1) only one ampule be used per patient and the remaining narcotic be handled according to a controlled substance protocol; (2) the neck of all ampules be wiped with alcohol and allowed to dry before being opened; and (3) bacterial filters be used on solutions going into the subarachnoid or epidural space.

References: 1. Anesthesiology 75:A835, 19912. Anesth Analg 74:S301, 1992

-

14

.-

_

TITLE: ORGAN SYSTEM FAILURE IN OBSTETRICS AS A PREDICTOR OF RISK AND OUTCOME

AUTHORS: R.B. Becker M.D., B. Nies M.D., MP ‘Ihiet M.D.. J~.Williams M.D.. M.P.H.. J. Grossman M.D., Ph.D., J.S. Naulty M.D.”

AFFILIATION: Depanmems.of Anesthesia and Obstetrics. George Washington University Medical Center, Washington DC 20037

Maternal morbidity and mortality have decliied over the past fifty years , particularly in critically ill patttnients. Still, there are few obstetrical services that use objective markers of critical illness to select patients who may benefit from admission to an intensive care unit. We have developed a model for early identitkadon and triage of critically ill pattarients to facilitate this process..

All pannrients (1~~1890) admitted to the George Washington University Hospital Labor and Delivery Suite between October 1. 1989, and September 30. 1990 were aasigwd an objective score ranging from zero to eight, baaed ott signs and symptoms of organ system failure (OSF). Scores were assigned upon admission to the Labor Suite and at four hours postpartttm. The OSF scoring system was based on the APACHE III critical illnessss scoring system, modified for pregnancy-related norms. Independent variables used to compose tbe OSF score included heart rate, mean arterial pressure. respiratory rate. PaCO2. AaDO2, urine output. semen BUN/Creatinine, WBC, PT. FIT. TI’, platelet count, hemoglobin level. fibrinogen level. and Glasgow Coma Score, body weight. temperature. presence of insulin dependent diabetes mellitus, presence of preeclampsia and presence of innaartwial or central venous pressure monitor. Patients with admission OSF scores of 2.5 or greater received joint consultations with matetnofetal medicine, obstetrical anesthesia critical care and neonatahgy servicea for development of a uearment plan. After delivery, patients exhibiting clinical evidence of critical illness were transferred to a sixteen bad medical-surgical ICIJ. Less critically iB pamuients whose iilness showed signs of improvement in the i-ate postpatmm @cd were monitored closely in the Labor and Delivery Suite until their illnew resolved or wonened enough to warrant tnttafer to tbe ICIJ. The decision to transfer tbe patient to tbe ICU was not baaed ott tbe OSF score.

Positive OSF scores occumd in 156 partwients (8.2%): ninety three women bad scores of 0.5.33 bad scores between 1.0 and 2.0, and 30 bad scmes of 2.5 or greater. No patient with a score < 2.5 required ICU admission or saffered additional maternal morbidity.compared to padents with OSF=O. Thirteett patients reqired KU admission, including two eventual maternal deaths. Pre- and postpartum OSP scores correlated with individual length of KU stay and were predicdve of actual admission to the ICIJ and length of ICU stays in those partutiems without preeciampsia (Fig 1). Seventeen parients with OSF scores of 2.5 or greater did not require ICU admission:. all of these 17 patients bad severe preeelampsia. which quickly resolved postpatmm. ‘Ibe only pree&mptic padents requiring ICU admission had other organ system diseases upon which tbe preeclampsia - supzimposed (chronic renal failure, lupus erytbematosas, etc.). No single variable or clinically meaningful group of variables other than the OSF score predicted dtuadon of ICU stay, contirming oar bypotbesis that the ~edicdve value of individual parameters was poorer than their combined value.

1 2 OSF &ORE

4 5

25

__.

m ANESTHESIA ROTATIONS FOR OB/GYN RESIDENTS. WHAT AREWETEACHINGTHEMANDWHATARETHEYLEARNING?

Authors Affiliation:

Birnbach DJ*, Grunebaum A, Stein DJ, Saunders T, Thys DM Departments of Anesthesia and OWGyn, St. LukeVRoosevelt Hospital, Columbia University College of Physicians and Surgeons, NY

INTRODUCTION. There is no consensus of opinion on whether o&yn residents need a formal rotation through an anesthesia service, or acquite enough anesthesia knowledge through interactions with anesthesiologists. In programs where a formal anesthesia rotation is mandated for ob/gyn residents, there is little in the way of standardixation of curriculum. To evaluate our anesthesia rotation for ob/gyn residents, we pnpared a written examination to be administered to ob/gyn resident.9 at different times of their training.

METHODS. An examination composed of 20 essay type questions was administered to all OwGyn residents ( 6 per year, a total of 24 residents). These twenty questions were asked on completion of the anesthesia rotation and again at diffuent intervals from 3 months after the rotation to 3 years later The same questions were administered to the first year Ob/Gyn residents, on their first day, in order to check their baseline anesthesia knowledge. The questions were divided into three main groups: l) General obstetric anesthesia knowledge- which included 10 questions on indications and conuaindications for regional anesthesia, complications of regional anesthesia, and complications of general anesthesia II) Specific Anesthesia questions- which included 7 specific questions about anesthetics, for example, what is the toxic dose of lidocaine?, how many mg am in each ml of lidocalne 2%?, which anesthetics are long acting or short actlng?and what concentration of which local anesthetic is used for labor epidurals? III) Philosophical questions-the following three questions were asked: Would you use anesthesia for forceps deliveries? Would you practice obstetrics in a hospital where anesthesiologists were not in-house? Has this rotation changed your perception of the role of the anesthesiologist on the labor suite?

RESULTS. Of the incoming interns, no questions in groups I or II were answered correctly. For the remaining 18 residents, all general and specific questions were answered correctly on the last day of their anesthesia rotation. When re-tested however, the results showed that ob/gyn residents only retained lmowledge about general anesthesia principles. Of the ten Group I questions asked, 15 of 18 examined ob/gyn residents answered all correctly. Of the seven specific questions, each was answered incorrectly by at least 15 of 18 residents. with no residency year doing better or worse than any other The results of the group III questions showed that all residents had come to appreciate anesthes& none would work in a hospital where anesthesiology was not in-house for 24 hours, and all stated that they now perceived the anesthesiologist as playing a major role in the labor and delivery suiklhis was a change from the opinions that they expressed before their anesthesia rotation.

DISCUSSION. The rotation of ot@yn residents on our Anesthesia service had several beneficial results. Fit, all obstetric residents came to appreciate the role of anesthesia in management of the parturient, thus allowing for good anesthesiologist-obstetrician relationships. Second, the residents learned and retained a large fund of general anesthesia knowledge, with emphasis on the advantages of regional anesthesia. Unfortunately, despite continuing “indimct interactions” with anesthesiologists, most ob&yn residents did not retain specific. quantitative anesthesia knowledge. Some of these specific topics am of gnat imporcmce in the safe management of patients. For example, despite the fact that all tested residents admitted to frequently using lidocaine when performing episiotomies, 16/18 did not remember the toxic dose of lidocaine. One possible remedy for the failure to retain specific anesthesia knowledge would be to initiate a second anesthesia rotation during their senior year. Last, the fact that 6 incoming ob/gyn residents from 6 different American medical schools had so little knowledge of anesthesia 2 weeks after medical school graduation, infers that medical school anesthesia curdculum should be. reassessed.

26

.-

.-

-

-

Title :

Author:

Affiliation:

The Validation of Arterial Oxygen Saturation Measurements in utero using Pulse oximetry

Harris AP

Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine. Baltimore, Maryland 21205

Introduction: A non-invasive measurement of fetal arterial oxygen saturation using pulse oximetry could be of potential use in assessing fetal well-being in utero during labor. In this study, the accuracy and technical feasibility of reflectance (as opposed to transmission) pulse oximetry in utero was evaluated in acutely instrumented fetal sheep using specially designed reflectance sensors. The effect of slight changes in sensor design on accuracy and reproducibility was assessed by studying a second sensor design. Methods: Three pregnant ewes at 130-140 d gestation were anesthetized and ventilated. A hysterotomy was performed and a right fetal axillary arterial catheter was placed for preductal arterial blood gas sampling. The fetal scalp was exteriorized, shaved, and a pair of identical reflectance oximetry sensors were placed on the fetal head. The simultaneous use of two sensors allowed for validation of the plethysmographic signal by enabling comparisons to be made between sensors. Sensors were held in place by an air bladder inflated to 10 torr. Fetal SaO, was varied from -6-83% by varying maternal FiO, from .14 to 1.0. At each stable level of fetal SaO,, in viva HbO, was determined by a hemoximeter, and a simultaneous oximeter signal was digitized. Following the experiment, an analysis algorithm was derived, SpO, was compared to in viva HbO,, and the standard deviation of the observed differences was calculated. In a second set of three animals, a different sensor was used (redesigned to improve manufacturability) and the experiment was repeated. Results: In the first three animals, 102 SpO, measurements were collected. Figure 1 shows the scatter plot of SpO, versus HbO, following algorithm calibration. The limits of agreement of these measurements (defined as + 2 S.D.) are + 10.92%. 177 SpO, measurements were made in the second set of animals. Analysis of data collected from the redesigned sensor indicated that a different algorithm calibration was necessary. Figure 2 shows the data following recalibration. The limits of agreement are + 7.86%. Discussion: Reflectance pulse oximetry appears to be reproducible, technically feasible and relatively accurate over the wide range of SaO, normally encountered in utero. However, recalibration of analysis algorithms appears essential, even after only minor sensor design changes, to maintain satisfactory limits of agreement at low SaO, values.

a7

_

_

TITLE: Does Painful Labor Increase Spinal Cholinergic Activity in Humans?

AUTHORS: James C. Eisenach, M.D.*, David D. Hood, M.D., Chuanyao Tong, M.D.

AFFILIATION: Department of Anesthesia, Wake Forest University Medical Center, Winston-Salem, North Carolina

Introduction: Pain itself activates an endogenous “analgesic” system which involves a spinal-supraspinal-spinal loop. This endogenous analgesia may explain in part the variability in perceived pain during labor and need for postpartum pain medication. Painful labor increases norepinephrine (NE) in cerebrospinal fluid (CSF) in women, supporting animal research which shows that pain-induced analgesia involves spinal NE release. Since spinal NE may relieve pain by causing ACh release, we tested whether painful labor increased ACh in CSF and whether this correlated with decreased perception of postoperative pain.

Methods: After written informed consent and IRR approval, 10 women having cesarean section under spinal anesthesia were studied over a 2 month period. A total of 20 women will eventually be studied. Women were divided into two groups: NO PAIN (scheduled, elective cases) or PAIN ( at least 6 hrs of painful labor prior to surgery). Visual analog score (VAS) for pain was obtained before and 24 hr after surgery, and 24 hr morphine use by iv PCA was recorded. Prior to local anesthetic injection 2 ml of CSF were obtained for subsequent NE and ACh analysis by an investigator blinded to group. Data are presented as mean of: SEM and will be analyzed by t-tests and Pearson correlation at the conclusion of the study.

Table I: CSF ACh & Postop Pain Results: To date 6 women have been studied in the NO PAIN aroun and 4 in the PAIN group. Only the PAIN group had pain before surgery (VAS =6.2? 0.8

CSF ACh POSTOP

cm). Power analysis reveals that should GROUP (pmol/mlI VAS (cm)

the current trend continue the PAIN group will have more ACh in CSF and

NO PAIN 34-11 6.120.8

less pain by VAS postop than the NO PAIN group. (Table I). CSF NE

pAzN 110266 4.620.2

analysis are pending.

Discussion: These preliminary data are consistent with the hypothesis that visceral pain, such as the pain of labor, activates a spinal choline@ system which can diminish pain perception. Correlation between CSF NE and ACh will reveal whether this cholinergic activation may be due to local NE release. One could speculate that, should these systems be important in endogenous analgesia, labor analgesia could be achieved by spinal injection of agents which enhance NE or ACh release or action. Supported in part by grant GM35523 from the National Institutes of Health.

-

_

._

-

Ii!k: Microcatheter Continuous Splnal Anesthesia: Potentlal for Neurologlc Injury In the Suplne Posltlon

m: Leicht CH, Vasdev G, Ross BK Departments of Anesthesiology, Mayo Clinic, Rochester, MN and University of Washington, Seattle, WA

introduction: Continuous spinal anesthesia(CSA) may have numerous advantages over other techniques in a variety of circumstances; however, it has been associated with a relatively high incidence of post dural puncture headache(PDPH) in certain patient populations. Several manufacturers(TFX, Kendall, PMP, others) have developed microcatheters for use in CSA in an attempt to decrease the incidence of PDPH. Unfortunately, there have been reports of permanent neurologic sequelae following the use of microcatheters for CSA’, which in most cases, has been associated with the use of CSA with 5% lidocaine with dextrose for operative procedures. Ross, et al*, indirectly (methylene blue/photospectrometry) measured lidocaine concentrations along a spinal canal model in the vertical position after injection of lCIOmg/2ml lidocaine at L3 and found very high sacral concentrations of lidocaine, consistent with those known to be associated with permanent neurologic injury. The present study differs significantly from the prior, in that all injections/measurements were performed with a spinal canal model in the lateral decubitus/supine position rather than upright and CSF lidocaine concentrations were measured directly rather than indirectly. Methods: A spinal canal model was fabricated utilizing cadaver measurements similar to Ross et al. The model was placed on a stand(modified to allow injections to be performed in a lateral decubitus position and then be immediately rotated to a supine position in a consistent manner) and filled with ‘mock’ CSF maintained at 37°C. Two injections each of 1.5 ml of 5% ‘hyperbaric’ lidocaine(with glucose 7.5%) were made via a 289 Co- SpanTM(Kendall) catheter at the L3 level in the canal under the following conditions: catheter tip up(cephlad), catheter tip down(caudad), injection over 6Os(slow), and injection over 20s(fast). Five minutes after injection, samples were obtained at the caudal end of the canal and every 5 ems cephlad for 30 ems; lidocaine concentrations were determined directly using EMlT(enzyme multiplied immunoassay technique), which was validated using “mock CSF containing known concentrations of lidocaine. Osmolality of each sample was measured using freezing point depression osmometry. &&8: Detailed results of the concentrations obtained for each sampling level along the spinal canal will be presented. In all cases, regardless of catheter position or speed of injection, peak concentrations of lidocaine were located at the caudal tip of the canal. Peak lidocaine concentrations(%.meati st dev) and osmolality(milliosmoles, mean&t dev) at the caudal tip were as follows:

up

d& down

. .

Osmolalitv slow 1.52 f 0.25 % 460.5 f 4.9 fast 0.65 f 0.06 % 362.0 f 2.0 slow 2.40 f 1.41 % 572.5 f 50.2 fast 1.40 f 0.42 % 411.0f22.6

Dlscusslon: Results were consistent with previous findings, in that the peak concentration of lidocaine was uniformly found at the caudal tip of the canal and was influenced by the direction of the catheter tip and rate of injection. In contrast, however, was the finding that not all peak caudal lidocaine concentrations were consistent with those known to cause permanent neurologic injury; eg., catheter tip up, fast injection rate was well below neurotoxic levels. Only in the case of a slow injection rate with the catheter tip down were the lidocaine concentrations consistently well above the neurotoxic threshold. The remaining two groups (up,slow and down,fast) were borderline with regard to the threshold for neurologic injury. References: 1. Rigler ML, Drasner K, et al: Anesth Analg 72:275-281, 1991 2. Ross BK, Coda B, Heath CH: Regional Anesth, March-April 1992

29

-

-

-

._

_

Tftle:

Authors:

Headache in Parturients After Dural Puncture: A Comparison of Three Needle

Types mArkoosh. MC Norris. M.D., BL Leighton, M.D., HJ Huffnagle, D.O., SJ Sharkey, M.D., J Lessin, R.N.

Afflllatlon: Departmentof Anesthesiology,Thomas Jefferson University, Philadelphia, PA 19107

Introductfon: Increasingly, obstetric anesthesiologists choose spinal anesthesia for cesar- ean section (C/S). Many, however, avoid this technique because of the possibility of postdural puncture headache (PDPH). The introduction of spinal needles with an atraumatic pencil point should lessen the incidence of this complication. A recent study of parturients found no PDPH following spinal anesthesia using a 24 gauge Sprotte needle (n=55) and a 14.5% incidence after using a 25 gauge diamond-tipped needle (n=55).(1) We compared the incidence of headache following spinal anesthesia for C/S using the following needles: a 25 gauge Whitacre. a 24 gauge Sprotte. or a 25 gauge Quincke. Methods: 217 parturlents presenting for C/S under spinal anesthesia gave oral consent to participate in this ongoing, IRB approved study. Patients assumed either the sitting or lateral position and underwent lumbar dural puncture with one of three randomly chosen needles: a 25 gauge Quincke (n=72, Becton Dickinson), a 24 gauge Sprotte (n=72). or a 25 gauge Whitacre (n=73, Becton Dickinson). At the discretion of the attending anesthesiologist, the patientsreceivedbupivacaine0.75%withdextrose, 12-15mg,with orwithoutpreservativefree morphine; We collected the following data: patient age, height, weight, gravidity, panty, and history of prior C/S. An investigator, unaware of the assigned needle type, visited the patient each day until discharge and inquired specifically as to the presence of a headache. We rated any headache using the following scale: mild=does not interfere with daily activ- ily, moderate=able to perform daily ac- tivities with difficulty, severezunable to I4 perform daily activity. We noted head- j I? ache location, duration, if nausea or :

* po.05. WMM “8. cilukclu

photophobia were present, if the head- { ” ache was positional in nature and the $ 8 need for epfdural blood patch. We con- tacted each patient at home one week i 6 after discharge to collect the same infor- g 4 mation. We analyzed the demographic z z data using analysis of variance and the headache data with chi-square or ’ Kruskaf-Wallis with the Mann-Whitney Days

U when appropriate. results: There were no demographic differences among the 3 groups. The figure tracks the dally headache number and severity for the first 5 postoperative days and at home. Patients in the whitacre needle group experienced significantly fewer headaches (~~0.02). The need forepidural blood patch was higher in the Quincke needle group (3173 vs0 in the othergroups). Dfecueelon: Preliminary results of this ongoing study indicate that parturients undergoing dural puncture with a25 gauge Whitacre needle experience fewer and less severe headaches in the eany postoperative period than those patients receiving adural puncture with a25 gauge -needle. 1. Anaesthesia 45:656-656, 1990.

32

-

-

-

_

._

_

-

Title: A Comparison of Epidural, Intratbecal and Intravenous Sufentanil for Labor Analgesia

Authors: Camann WR, Denney RA. Holby ED, Datta S Affiliation: Brigham and Women’s Hospital. Harvard Medical School, Boston, MA

Lptroduction: Several recent studies have questioned whether the route of administration impacts upon analgesic efficacy for highly lipid-soluble opioids. Fentanyl(l), sufentanil(2), alfentanil(3) and butorphanol(4) have all. under various condition, provided equivalent analgesia when given either IV or epidurally. We sought to determine if intrathecal (IT) administration of a fixed dose of sufentanil differed from either IV or epidural use of this agent.

Methods: Nineteen ASA I panutients requesting epidural analgesia during active labor consented to this institutionally approved protocol. A 4 l/2” 17G epidural needle was placed into the epidural space, whereupon a 4 11/16” 25G Whitacre needle was placed through the epidural needle into the subarachnoid space. All patients received, in a randomized, double-blind fashion, an intrathecal (2 cc), intravenous (2cc) and epidural (IO cc) injection at roughly the same time. One of the injectates contained 10 mcg of sufentanil, the other two only saline. After removal of the Whitacre needle, an epidural catheter was placed, but no local anesthetic administered. Visual analogue scores (O-10) were obtained by a blinded anesthesiologist at time of study drug injection (time zero) and 10. 20, 30, 40, 60, 90, 120 minutes thereafter. Patients could request additional analgesia (epidural bupivacaine) anytime at least 15 minutes after study drug injection. Data were compared using Kruskall-Wallis ANOVA, with p < 0.05 considered significant.

Results: The duration until first request for additional analgesia after study drug injection was 30 h 8 min in the IV group (n=6), 26 5 9 min in the epidural group (n=6). and 82 2 27 min in the IT group (n-7) (p < 0.001). VAS scores were equivalent for all groups at time rem (IV: 7.7 + 1.8. Epid: 7.8 + 2, IT: 8.7 2 1.9). At 10, 20, and 30 min after time zero, VAS scores for the IT group decreased to 2 + .2, 1.2 + 1.2, and 2.5 + 2, respectively. (p < 0.01 vs. time zero score). VAS scores in the IV and epidural groups did not decrease and remained significantly elevated vs. the IT group at all observation points. No patient complained of dysphoria, excessive sedation, nausea or demonstrated abnormalities of FHR tracing. No patient developed PDPH. Two patients in the IT group complained of pruritus. one moderate, the other severe.

Intrathecal administration of sufentanil, 10 mcg. provided rapid. effective analgesia for l-2 hrs during labor. IV or epidural administration of the same dose of sufentanil failed to provide demonstrable analgesic effects. Intrathecal sufentanil may be considered a useful adjunct to the initiation of epidural analgesia during labor. Further studies using microcatheter techniques may allow expanded use of this agent.

References:

1. Anesthesiology 72:981-986. 1990. 2. Anesthesiology 68:129-134. 1988. 3. Anesthesiology 75:171-178, 1991. 4. Anesthesiology 76:216-220. 1992.

- 33

-

_

-

-

-

Title: Incidence of Cesarean Sectton Does Not Increase with lntraspinal Analgesia for Labor

Author: Knape KG, Rand R

Affikation: Untversky of Texas Heaith Science Center at San Antonio

INTRODUCTTON: The effect of intmspinal analgesia (ISA - epidural and IntrathecaT) for labor on the incidence of cesarean section (C/Sx) continues to be debated. The potential to increase C/Sx rate has been documented’. yet wtth property managed intraspinal techniques the rate of operative or lnstrumentai deiivertes does not increase.? The following Illustrates the association of C/sX rate and ISA at our instttution.

METHODS: The statistics generated by the Obstetdc Anesthesia DMsion from January. 1988nuary. 1992 were reviewed. me C/Sx rate (# of CJSxs dMded by the total # of deliveries) is computed monthly. as Is the labor analg6sia rute (total lSAs - the sum of the # of labor epldurais (LEA) ptus # of intrathecat narcotics (RN) for labor plus t of combined techiques (iTN with LEA) for labor, dtvided by the total of the total # of deilveries minus the # of C/Sxs.) LEAs used again later for cesarean sectlon anestheti are counted separately.

RESULTS: The graph below demonstrates that despite an increase in the use of ISA over the lost four years, the C/Sx rate has remained essentloliy stable. The C/Sx rate for 1988 was 14.2% white the labor epidumi rate was 26.6%. Thls was the tlrst full year using continuous infusions but not yet intrathecai narcotkzs. in December, 199U we began routine use of ITNs for labor, often wlth an epidural catheter placed for !ater actiiation. The C/Sx rate for 1991 was 14.8% while the iSA rate had risen to 49%.

OI,,,,~,~,,,,,,,,,,,,,,,,,,,,,,,,,,~,,,,,,,,,,,,,/ JB~MMJJASONDJsgFMAMJJASON~JOFMAMJJA80NlllFMAMJJASONDJ

92

DISCUSSION: The acceptance of RN for labor analgesia by our Obstetrtc colleagues increased the proportion of parturients that could be provided superior pain relief. Though the resultant lack of net change in C/sX rate is similar to the findings of other ‘disaster models’ to a certain extent’ (one variable changed while all others remained fixed). our Obstetricians contributed to maintaining the C/Sx rate by closely monttortng It with weekiy C/Sx conferences to quide de&ion mating and limit the use of ‘soft lndlcations for operative intervention.

CONCLUSION: We found no ovemll change In C/Sx rate despite an increase In ISA for labor. With careful lntrapartum management and understanding of the proper use of, as well as the effects of, analgesic techniques on labor, the perlnafol Team can cooperatively minlmlze the need for operative delivery.

REFERENCES: 1) Thor-p JA, Parisl VM, Boylan PC, et al. Am J Obstet Gynecoi 16167s 5.1989 2) Philipsen T. Jensen NH. Europ J Obstet Gynecol Reprod Bioi m27.1989 3) Chestnut DH. Laszewskl LJ. Pollack KL et al. Anesth 72613.1990 4) Nauity JS. Smkh R, Ross R. Anesth 69:A66Q. 1988

- 34

Title:

Authors:

Affiion:

Relationships Among Intravenous Hydration, Ephedrine Dose, and Maternal and Neonatal Colloid Osmotic Pressure at Cesarean Delivery

Hauch, MA, Hartwell, BL, Q&&$, Datta S

Deparmrent of Anesthesia, Brigham and Women’s Hospital, 75 Francis Street, Boston, MA 02115

Imroduction: Plasma colloid osmotic pressure (COP) is a reflection of the plasma protein concentration and regulates fluid movement across a permeable membrane such as the capillary wall. COP declines to the same degree with intravenous hydration of healthy parturients undergoing vaginal or cesarean delivery regardless of the type of anesthesia used when measured 8 to 24 hours postpartum. 1 We investigated the acute effect on COP of intravenous hydration for cesarean delivery under spinal anesthesia by comparing maternal COP at insertion of the intravenous catheter (MVt) and at the time of delivery (MV2). We also measured the maternal ephedrine requirement to observe its correlation with COP. We measured umbilical artery (UA) and vein (UV) plasma COP to detetmine if vigorous mammal innavenous hydration or use of ephedrine alter the neonatal COP.

Methods: The study protocol was approved by the Committee for the Protection of Human Subjects, and all patients gave informed written consent. To date, 12 healthy term parturients who had consented to spinal anesthesia for elective cesarean delivery have been studied. Maternal blood samples were obtained at intravenous insertion (MVJ) and at delivery (MV2). Spinal anesthesia using 0.75% hyperbaric bupivacaine with fentanyl 10 pg was administered after infusion of 1.500 cc Ringer’s lactate. Intravenous ephedrine was given for systolic blood pressure ~100 or a drop of 20 mmHg. The amount of fluid administered until delivery was recorded. UA and UV samples were obtained from a doubly clamped segment of umbilical cord. All samples were collected in tubes containing sodium heparin (143 IU), centrifuged, and the plasma decanted. COP was determined in triplicate for each sample using Wescor 4420 colloid osmometer after daily calibration with Osmocoll. Analysis of the data was by paired Student’s t-test and linear regression where appropriate. The criterion for statistical significance was p&05.

Results: The mean f SEM MVt COP (22.4M.5 mmHg) was significantly different from the MV:! COP (15.8?0.4), p<O.OOl. UV and UA COP values were significantly different (18.8M.4 vs 20.4ti.4). pcO.001. MV:! COP was significantly lower than UV (~~0.01) and UA (p<O.OOOl). There was no correlation between intravenous hydration (2558f132 ml) and MVI. MV7. UV. UA COP values or euhedrine dose. However. there was a significant co&latioi between the ephedrine dose iequired and MV1 COP (t&.61) as well as UV COP (d.56).

Discussion: A significant decrease in maternal COP was found at delivery. Rapid intravenous hydration and fluid redistribution have been suggested as causes for this reduction.2 Although no significant correlation between total fluid administered and maternal COP was noted in our study, this was most likely due to small differences in total hydration among patients. Of interest is the previously unreported finding of significantly higher neonatal COP values compared to maternal COP at delivery, possibly related to fetal and placental homeostatic mechanisms. In addition, higher baseline maternal COP and W COP values were significantly associated with greater ephedrine requirements. Further studies are needed to clarify this observation and to apply these findings to high risk populations. 1. Cotton DB: Am J Obstet Gynecol 149:174,1984 2. Gonik B: Am J Obstet Gynecoi 150:99,1984 ._

-

35

_~

_

Title: Monitoring Practices for Epidural Analgesia in Obstetrics Authors: Minnich ME, Minnich SJ Affiliation: Gaisinger Clinic, Dept. of Anesthesiology, Danville, PA 17822

Introduction: The combined forces of technical progress, good patient care, and the medico-legal milieu have resulted in the establishment of standards for intraoperative monitoring.’ These standards specifically exclude the laboring patient. It follows that standards should also evolve regarding monitoring of the laboring parturient. In fact, guidelines for conduction anesthesia in obstetrics have recently been adopted.’ It is widely accepted that epidural analgesia for labor is not risk-free. Our survey seeks to establish the de facto standards of common anesthetic practice in labor & delivery.

Methods: We mailed 1055 questionnaires to subscribers of the SOAP Newsletter obtained from their mailing list. The survey sought data regarding size and type of practice, teaching obligations, and monitoring routines for labor epidural analgesia. No outcome data were requested. While the majority of questionnaires were mailed to US subscribers, foreign subscribers were included. The data were compiled and analyzed using STATA 2.10. The following results emerge from tha 465 completed surveys returned at this time.

Results: Of the 1055 surveys mailed, 473 were returned (44.8%). Eight were returned uncompleted due to retirement, no obstetric unit or other reasons. Of the 465 surveys included in the analysis, 434 (93.3%) were from the USA, 23 (4.95%) from Canada, and 8 (1.72%) from other countries. Some institutions were represented by multiple questionnaires and these were consolidated to a single response. Of ES:.-* R~“Pm”=aK,.sorrra the 324 institutions, 91% were USA, 6% Canada, w and 3% other: 59% have teaching programs (i.e., lol anesthesia residency, nurse anesthesia school, or 5 both), 98% offer labor epidural service (of which, 85% have 24 hour ‘in house” coverage). Of the

g u

2 IDI USA respondents, 74% indicate that epidural s blockade is performed by physicians only, 26% llD allow any member of the anesthesia care team’ to D place epidural catheters; 24 hour coverage was

-II wLLII*

provided by physicians in 64% of institutions, and Figure 1: Monitoring Practices

by an Anesthesia Care Team in 36%. figure 1 shows the distribution of monitoring practices.

Correlation coefficients (Pearson1 reveal no differences in routine monitoring despite different teaching obligations, deliveries per year, and physician vs. care team coverage. Comparison of the USA and Canadian monitoring practices reveals a difference in the percentage of respondents using no monitoring equipment: during placement of epidural catheters, USA 1.7%, Canada 10.0% lP<O.Ol); during maintenance, USA 2.8%. Canada 20.0% (P~O.001); during delivery, USA 3.2%, Canada 30.0% fP<O.OOl).

Discussion: The above information demonstrates that 2.5% of respondents (10% of Canadian) use no monitoring equipment during epidural blockade placement. The vast majority employ non-invasive blood pressure cuff alone (54.7%) or in combination with other monitors 197%). Interestingly, during blockade maintenance, the use of blood pressure cuff alone increases (72.2%) and multiple monitors diminish. Monitoring during delivery in the USA is similar to that during placement of epidural catheters; Canadians decrease use of monitors for delivery (30% use none). While the number of Canadian respondents is small, the data demonstrate some vew intriguing differences in the practice habits among the respondents.

References: I. Standards for Basic Intra-Operative Monitoring (Approved by ASA House of Delegates 10186 and last amended 10/90). 2. Guidelines for Conduction Anesthesia in Obstetrics (Approved 1 O/91 I. 3. Anesthesia Care Team (Approved 1 O/87).

_

- 36

.-

TITLE: Efficacy of intntheol meperldine as the sole anesthetic for postpartum tubal ligation AUTHORS: Dickerson SE, Bailw SI. AFPKIATIONz Dept of Anesthesiology, Portsmouth Navel Hospital, Portsmouth, VA 23708 Intrcductlon: Intatheal meperidine es a sole anesthetic agent provides surgical analgesia for short procedures, rapid return of motor function, no respiratory depression (l),and excellent postoperative analgesia for variable periods of time. (l-3). This shldy compares inhathecal meperidine to a lidcaine conhul for PPlZ in terms of onset, duration, quality of block, recovery time, post-op analgesia and side effects, end effects on respiration end oxygen saturation. Methods; Folkwing IRB approval, ASA I/II patients scheduled for PI% were randomized to receive either en eppmptite dose of 5% lidcaine, or PF meperidine (100 mg/cc) combined with an equal volume of 10% dexhuse, after up to 2 mg IV midazolam as premeditation.

m ’ “uotoS3” SYU ‘,, 5’6”u DtlS9 5% lidocaine 60 w3 70 mg ama (RLD position)

70 mg 80% 90 mg Wing) Meperidine 5Omg 6Omg 70 rng GUD)

6Om.g 70 mg 80 mg WtinP, Doses were chosen after a pilot study using meperidine, and ail data was gathered by a blinded investigator. Patients were placed on continuous pulse oximetry (with memory end printout) upon entering the OR and continued until 10 hours after their block. After baseline measurements end every thirty minutes themafter, and on admission to the PACU, RR, sedation scale, block level,VAS, and Bm- mage scale for motor block were determined every 30 min until discharge. Patients received 0.05 mg/kg of morphine upon request for pain in the PACLJ, and all patients were placed on a demand only PCA morphine for postop analgesia After PAClJ discharge, patients were monitored hourly for VAS, respiratory ate, PCA morphine use, sedation sale, end continuous S&X? for 10 hours after placement of the intrathecel agent. PCA use wes discontinued at 10 hours, oral pein meds used thereafter were recorded. Results: Of the 30 patients studied, 14 received meperidine (group I), and 16 received lidocaine (group 2). The patients in Group 2 showed significantly more motor blwk, longer Ret Rm stays (due to resolution of motor block), and higher total PCA morphine usage post op than did the meperidine group. The patients in Group 1 had significently more pm&is requbing treatment then those in Group 2 Two patients in Cp 1 required no post operative analgesiaThere were no statistically significant dif&ences between the groups for nausea, sedation, urinary retention, or deseturation incidents.

usglpn; Intrathecal meperidine as e sole anesthetic agent provided reliable motor end sensory blockade for inha-abdominal procedures under 45 minutes duration. Pmritis was commonly seen, but easily treated with neloxone (100 mcg). The rare cam of se- desahration(<90%.) inta-ap end in the recovery mom responded quickly to neloxone, and no episodes of severe desahuetion occurred after resolution of the block. The benefits of this agent over lidcaine ere significantly shorter recovery mom stays end less post operative pain. Inhathecel meperidine should be considered for use in patients presenting for post perturn tubal ligation, and other short surgical procedures with moderately severe wsbxwetive rain.

Grow 1 (Metxaidine) Gmuo 2 (Lidocainel 29.5 mill 27.9 mill

hiIax height Seneoj blk $ T3 (cgT6) T3.69 (CbT5) Mean duration Motor blk. B25mbl 134.25 min Recovery Room time (to d/c)* 39.4 min 90.7 min TimetoletPainmeds (min) l 397.7 855 TotalPCAMSO4(mg) t 9.9 (ti dev=1126) 215 (std dev=9.3 ) l = P<.LxlOl Desehuetion incidents (meen per pt) t= P<.!xl5

inha*p $ 2.5 &alge=c-28) 0.125 $=No stat signif.

recowry~m$ 214 0.19 (t-test end

W’-oP $ 135 1.43 Mann-Whitney) References 1. Famewo CE, Naguib M: Spinal anaesthesia with meperidine as the sole agent. CASJ., 1965; 32: 533-7. 2 Acalovschi I, et al: Saddle block with pethidine for perineal operations. Br J Anaes., 1986; 58: 101246 3. Johnson MD, et al: Continuous microcatheter spinal anesthesia with subarachnoid meperidine for Labor and delivery. Anesth Anal&, 1990; 70: 65861

37

__

.-

-

_

_

-

Title: TEE RATERRAL AND RRORATAL EFFECTS OF DESPLURANE ANRSTRRSIA FOR CESAREAN SECTION

Authors: TK Abboud, ND, J Zlhu, ND, &j Richardson, MD, E Peres Da SilVa, MD, M Donovan, MD

Affiliation: Department of Anesthesiology, Los Angeles County+ University of Southern California Hedical Center, Los Angeles, California 90033

Introduction: Desflurane is a new inhalational agent with very low blood gas solubility (0.42) which undergoes minimal metabolism. Desflurane has been extensively studied in animals and in non-obstetrical patients. The present study was undertaken to evaluate maternal and neonatal effects of desflurane compared to enflurane for general anesthesia for cesarean section. Methods: Thirty-nine healthy parturients undergoing cesarean section were studied after approval by the institutional review board and informed consents. Patients were randomly assigned to receive either 3% desflurane (n=ll) 6% desflurane (n=14) or 0.6% enflurane (n-14). These concentrations are end tidal. Fifty percent N20 and 0

Fc

was added in each case. Anesthesia was induced with 4mg g sodium- thiamylal followed by 1.5mg/kg succinylcholine and endotracheal intubation. After delivery of the baby N20 concentrations were increased to 66% and the concentrations of desflurane or enflurane were maintained or adjusted as clinically indicated. Neonates were evaluated by Apgar Scores at 1 and 5 min., cord acid base status and the neurological and Adaptive Capacity Scores (NACS) at 2 and 24 hrs of age. Pre and post-operative hematocrit and estimated blood loss were compared. Maternal blood and urine were obtained pre and post-operatively to determine the hematological and the biochemical profile. Incidence of maternal awareness was also noted. Data were analyzed for statistical significance using the Student's t-test or chi-square when appropriate. A P value eO.05 was considered statistically significant. Results are presented in the table and they indicate that addition of desflurane or enflurane to 50% N20 did not produce any significant differences in neonatal outcome. None of the patients had any intraoperative awareness. Patients in the 3% desflurane group had significantly lower blood loss compared to ’ the enflurane group. No biochemical changes were noted in any of the patients. Discussion: Desflurane is a safe supplement to N O-O2

A mixture

for cesarean section. Neonatal outcome was good an no evidence of excessive uterine bleeding was noted. Desflurane 3% seems to be an adequate concentration for cesarean section. Clinical Results: Desflurane 6% Desflurane 3% Enflurane 0.6%

n=14 n=ll n=14 Blood loss (ml) 879294 727+52* 1086+146 Apgar Scores 0:

1 min. 5 3 3 5 min. 1 0 1

NACS ~35 at: 2 hr. 6 4 3 24 hrs. 1 1 0

* P ~0.05 compared to enflurane.

38

-.

-

_

CONCEALED AORTOCAVAL COMPRESSION DURING EPIDURAL PLACEMENT. (a study of cardiac output during epidural placement in parturients). Andrews P.J.D., Juneja M., Ackerman W.E., Rigor B.: University Department of Anesthesiology, University of Louisville, School of Medicine, Louisville, Kentucky 40292.

Introduction. Concealed aortocaval compression (CAC) during epidural placement in the lateral position has been reported (D.B.Scott) and insertion in the Sitting position recommended. The aim of this prospective, randomized study was to assess the incidence of CAC in the lateral and sitting positions during epidural placement at term.

Methods. Following Institutional Review Board approval and patient informed consent. Forty ASA I or II term patients requesting epidural analgesia for labor were randomly allocated into one of two groups. The first group (n=22) received their epidural in the lateral position (L2-3 or L3-4 interspace) using a 17G Tuohy needle. The second group (n=l8) were treated in a similar manner but in the sitting position. All the patients were prehydrated with lOOOm1 of Lactated Ringer's Solution and had normal blood pressure recordings before their epidural.

Cardiac output (CO) was measured continuously for 5 minutes before epidural placement, during and thereafter for 15 minutes using the BoMED NCCOM3 thoracic electrical (TEB) bioimpedence monitor. Blood pressure recordings at 1 minute intervals were entered into CDDP software (BoMED). The data were analyzed using ANOVA, Mann Whitney Wilcoxon test and Chi Squared test as appropriate.

Results. There were not significant differences in demographic data between the two groups (ANOVA). In the lateral position 76.5% of patients demonstrated a >25% reduction in CO compared with 30.8% of the sitting group (P=O.OOZS). The decrease in CO in the lateral position group was significantly greater than the sitting group (P=O.O006). No patient exhibited overt aortocaval compression.

DC0 %DCO Sitting median -0.8 lmin" -9.8%

IQR -3.8 to +2.2 lmin" -32 to+36%

Lateral median -3.2 lmin" -29.8% IQR -4.8 to -1.3 1min-l -44 to -17%

rIQR=inter-quartile range: DCO=chanqe in CO1

Conclusion. Epidural insertion in the sitting position is less likely to cause CAC.

Reference: In A Practise of Anaesthesia. Wylie and Churchill- Davidson (ed). 4th edition.

_

-

39

-

- TITLE: BETADINE@ - SEPTIC OR ANTISEPTIC?

AUTHORS: Birnbach DJ *, Kitain EM, Murray 0, Stein DJ. Saunders TA. Sordillo EM

AFFILIATION: Departmenls of Anesthesia and Pathology, St. Luke’s/Roosevelt Hospital,

Columbia University College of Physicians and Surgeons, New York. NY

Inlroduction. Povidone-iodine (Betadine @-Purdue Frederick Co.. Norwalk CT 06850) is an iodine solution

with high bactericidal activity which is widely used for skin antisepsis prior to regional anesthesia. Several

reports (1.2) have described the contamination of Povidone-iodine (PI ) with various organisms. The aim of

this study was to determine whether routine skin disinfection procedures using PI prior to epidural

anesthesia were effective. Additionally, we asked the following questions: (1) Can bacteria be isolated from

PI solution or from the plastic bottle cap? (2) Is there a difference in recovery of organisms from skin

prepped with a newly opened vs. a previously opened bottle of PI? (3) Is the gross visual appearance of PI

bottle or cap a good indicator of the presence of bacteria?

M&Q&_ The initial study involved the retrieval and culture of thirteen bottles of PI which were in current

use on the labor floor. The second segment of the study involved culturing the third PI sponge stick used to

prepare the patient’s back, along with the bottle of PI solution used. After removing the cap from a 473 ml

bottle of PI, the solution was poured into the space provided on the epidural anesthesia tray. The PI bottle

was routinely handed to the anesthesiologist by the labor nurse, who was unaware of the study. The back

was prepared in the usual manner. with three sponge sticks. The third sponge stick, however, was not

allowed to touch any area that had not been prepared by the tirst two sponges. 38 previously used betadine

bottles and the associated sponge sticks were sent to microbiology and compared with 37 new bottles of PI

and the associated sponge sticks. 10 new bottles of PI and IO sponges which were immersed in those PI

solutions but not used for skin preparation were sent to microbiology and examined as controls. The

samples were all coded and the microbiologist blinded. All specimens were inoculated to chocolate, 5%

sheep bled. and McConkey agars and cooked meal-glucose broths incubated at 37* C for 72 hours and

examined daily for growth. Isolates were identified using standard methods. Statistical analyses were

performed using Fisher Exact Test. A p < 0.05 was considered significant.

w Of the 13 bottles in phase I of this study. 3 caps and 3 PI solutions

grew out organisms which included mhemolvtjcus, w

-and pmseudomonas) In the second phase BACTERIAL GROWTH

of the study. no PI solution. new or used, grew organisms. There was. however.

a marked difference noted in lhe recovery of organisms from sponge sticks used in

skin preparation when the PI solution was from new vs. previously used bottles.

Of the 38 swabs which had been soaked in PI taken from used tn~tles.16 swabs

yielded bacteria. including v mda in addition to the

above mentioned organisms. By comparison. of the 37 swabs which were soaked

in PI solution from new boltles only two grew bacteria. Since these organisms

were not found in the PI solution, lhey mosl likely originaled on the patient’s back

and were tmt adequately removed by PI solxion fom previously opened bottles.

No organisms were retrieved from the 10 control PI solutions and sponges.

a. The results of this study confined previous repotis of bacterial growth occurring in PI

solution. Addilionally, we were able to culture bacteria from the plastic bottle caps. The appearance of the

boltle or cap was not a good indicator of bacterial contamination: the worst looking bollle grew no bacteria

and a boltle thal grew Pseudomonas appeared clean. In one case. a sponge stick grew out the same

organism that was isolated from the PI bottle cap. disproving the old teaching that unscrewing PI caps prior

to pouring prevents contamination of the satulion. Since bollles that have been previously opened are more

likely to be contaminated with organisms and freshly opened botlles seem to be more effective in removing

organisms from the skin. we suggest that manufacturers add single use sleriIe PI packets to all epidwal and

spinal kits. We further suggest that anesthesiologists should not reuse multiple use PI bottles when

performing any invasive procedure requiring skin antisepsis.

l.Berkelman RL et al. Ann Intern Med 1981:95:32-36. 2. Craven el al. New Engl J Med 1981;305:621.3

- 40

_..

_

-

-

COKPARISON OF 25G WBITACRE VS 24q SPROTTE SPINAL NEEDLES FOR CESARRAN SECTION

AUTEORS: CHIPDELL DC, PAW TJG, FLANAGAN IU, IWORLAND GE, IxXJGLAS IiJ

AFFILIATION: DRPARTHRRT OF AlImmIA, PACOLTY OF HEDICINE, ONIVRRSITY OP BRITISE COLDHEXA MD GRACE DOSPITAL, 4490 OAR STRRET, VANOXJVRR, BRITISH COLORBQ, V6H 3V5 CANADA

IHTRODOCTIO& Post-spinal headache (PSI0 is still a frequent co&ration of spinal anesthesia. Although the incidence of PSD

g ~;~$o;;a;ee&l;;as&t~ ;;

our institution. The purpose of this prospective,

randouizsd, double blind study was to coupare the incidence of PSE and failed blocks usinq the 24G Sprotte Or 256 Whitacre needles for Cesarean sections. As well, the effectiveness of anesthesia and other couplications were evaluated.

ll?moIts’ -. Pollouin Ethics Coxmittee approval and info rJ consent, 174 ASA 1 and 2 wouen underqoinq spinal anesthesia for elective Cesarean section were recruited. The patients were randouized into two groups having spinal anesthesia delivered with either the Sprotte (n=88) or Whitacre (n=86) needle. Patients were blinded as to which needle was utilized.

Ryperbaric 0.75% Dupivicaine, horphine 250 uq and Pentanyl 10 ucq were aduinistered to provide anesthesia to the T4 deraatone . Difficulty of insertion, dose of bupivicaine, effectiveness of anesthesia, and whether hypotension resulted were dccwented.

Postpartuu, the patients were assessed daily for 5 days by a blinded investiqator. Patients were questioned as to the presence of a headache and any treatuent was documented. A PSD was defined as a headache aqqravated by upriqht positioninq and relieved supine.

Data were analyzed usinq the unpaired T-Test, Chi Square and Pi&r’s Exact test where appropriate and PcO.05 uas considered siqnificant.

RESDLTS: There were statisticallvsionificant differences win4 respect to the deucqraphic data, difficulty of insertion, bupivicaine dose, or onvrrence of transient tiypotension.

The Wbitacre needle provided sore effective anesthesia as 95% of patients required no suppleuentation to subarachnoid blockade, coupared to only 81% with the Sprotte (P<O.Ol). Three (3.4%) failed blocks were reported with the Sprotte, but only 1 (1.2%) with the Whitacre. 34 (20%) non-spinal headaches were reported postpartuu, 20 (23%) with tbe Sprotte and 14 (16%) with tbe Waitacre. Four PSE were docusented with the Sprotte (4.5%): however, none were reported with the Whitacre.

DIXDSSION: The results of this onqoinq study indicate both needles have a sirilar ease of insertion and low incidence of insertion failure. However, the Sprotte needle delivered statistically less effective anesthesia and resulted in 3 failed blocks. This supports the hypothesis that the sprotte needle’s large ejection port allows inadvertent injection of soae of the anesthetic solution subarachnoi~~~~~~.l,~epidural space during

The Sprotte needle’s high incidence of PSE (4.5%) was most likely due to its larger size.

Although sore data are currently beinq collected, the 25G pencil point Whitacre appears to comply with the necessary requireuents for technical ease of insertion, delivery of effective anesthesia and paucity of PSE. The Wbitacre needle is also less expensive than the Sprotte needle.

REFERENCES: 1. Anaesthesia 1990;45:656-8 2. Regional Anaesthesia 1987;10:104-8. 3. Anesthesiology 1991;75:717-8

._

_

._

-

TITLE: .

The Role of Endogenous Vasopressln in Maintaining Blood Pressure Following Spinal Anesthesia

AUTHORS: AFFILIATION:

H. Carp, D. Garvey, R. Vadhera and A. Jayarem Dept. of Anesthesia, Oregon Health Sciences University, Portland, Oregon 97201

Introduction: Current evidence suggests that endogenous vasopressin plays an important role in maintaining blood pressure under conditions in which the sympathetic nervous system is impaired. In fact, a study in dogs demonstrated that endogenous vasopressin supports blood pressure and prevents severe hypotension following epidural anesthesia.' Experimentally the role that vasopressin plays in maintaining blood pressure can be studied by administering a specific antagonist of the vascular action of vasopressin and measuring the resultant effect on blood pressure. Therefore. we administered a vasopressin V,-receptor antagonist to patients undergoing spinal anesthesia and measured the effects on blood pressure compared to spinal block alone. Methods: The study group consisted of 28 healthy patients, 18-50 years of age and scheduled for elective gynecological surgery under spinal anesthesia. Blood pressure was recorded at three minute intervals using a non-invasive blood pressure monitor throughout the study period. Following a fluid bolus of 500 ml of 0.9% saline, patients were randomly assigned to receive 0.5 mg of the vasopressin antagonist B-mercapto-B, B-cyclopentamethylene-proprionyl-o-Me-Tyr-Arg-vasopressin, dissolved in saline (n-11) or saline alone (n-9), intravenously." [This dose of antagonist has been shown to completely inhibit endogenous vasopressin.]' After 15 minutes, 15 mg of 0.75% hyperbaric bupivicaine was injected intrathecally and the blood pressure response recorded. Eight additional control patients received the vasopressin antagonist alone without spinal anesthesia after which the blood pressure was measured as before. The upper level of the block was estimated using loss of pinprick sensation. Vasopressin plasma levels were measured pre and post-spinal block using a specific radioimmunoassay. Data are expressed as mean + SE. Results: Following blockade of endogenous vasopressin, spinal anesthesia resulted in a maximum decrease in mean blood pressure of 17 f 9%. After spinal anesthesia alone, the decrease in mean blood pressure (15 + 8%) was not significantly different compared to the vasopressin blocked group (p-0.4). The upper level of spinal block to pinprick was similar in both groups (Tl k 3; T2 + 2 respectively). Vasopressin blockade in the absence of a spinal block did not effect blood pressure (data not shown). Furthermore, plasma vasopressin levels were unchanged following spinal anesthesia (data not shown). Conclusion: In contrast to previous results obtained in dogs2, our results in humans suggest that endogenous vasopressin does not play an important role in maintaining blood pressure following spinal anesthesia. References: 1. Peters J, et al: Anesth 73:694-702, 1990. 2. Manning M, Sawyer WA: Ann Int Med 96:520, 1982. 3. Gavras, et al: Hypert 6:156, 1984.

This study was supported by a grant from the Medical Research Foundation of Oregon.

42

-

-

._

_

._.

_

-

Title: Effect of Continuous Fetal Cocaine Infusion on Fetal Cerebral Blood Flow and Metabolism.

Authors: Chao CR, Morishima HO, Jack KE, Daniel SS

Affiliation: Depts. of Obstetrics and Gynecology and Anesthesiology, Columbia University, New York, New York 10032

Introduction: Although cocaine use during pregnancy is associated with behavioral and structural abnormalities in the newborn central nervous system, its physiological effects on the fetal brain and its blood supply are largely unknown. We sought to determine the effect of a continuous fetal cocaine infusion on fetal oxygenation, cerebral blood flow, and metabolism in chronically catheterized near-term fetal sheep.

Methods: Cerebral blood flow (nonradioactive colored microspheres), glucose and lactate concentrations, and blood gases were measured before and during 60-minute intravenous fetal cocaine HCl infusions (n=5) in near-term fetal sheep. A 2 mg/kg loading dose was given followed by a continuous infusion of 1 mg/kg/min. Blood samples were taken and cerebral blood flow measured following 15,30, and 60 minutes of the infusion.

Res&~ Brachial arterial p0.a decreased from 20.3 to 14.5 Ton at 15 minutes and remained below control throughout the infusion. Glucose and lactate concentrations increased by 28 and 87 % respectively at the 15 minute sampling and remained elevated thereafter. Cerebral blood flow increased from 116 to 371, 308, and 190 ml/ mm/ 1OOg at 15, 30, and 60 minutes respectively; cerebral vascular resistance decreased from 0.36 to 0.16, 0.23, and 0.22 mm Hg/ ml/ min/ 1OOg at these times. Glucose uptake increased from 11 umoles/ min/ 1OOg to 31 at 60 minutes.

Discussion: These findings suggest that in contrast to bolus fetal infusions, where oxygenation was not affected by cocaine (Woods, et al, JAMA 257:957-961), continuous fetal infusions decrease fetal arterial oxygen tension. The data do not support a vasoconstrictive effect on the cerebral vasculature; instead, cerebral blood flow exceeded that which would be expected from this degree of hypoxemia (Jones, et al, AJP 235(2):H162-H166). This cerebral vasodilation may be secondary to increased metabolic rate and enhanced production of a metabolic vasodilator.

Supported by NIH Grant HD 26600

43

Lidocaine Phannwoklnetirr after BpidunI Anesthesia for Cesarean Section

J.W. Downing. M.D.. RF. Johnson. V. Jobnmn. M.D.. MWmd. MD.. N. Herman. M.D.

DivisionofObstetricAnesthe4Department ofAn~h~ologg,VnnderbiItUnivenlty. Nssbville.TN..

USA 37232

Intmductlon. Locslm~hetirr~~~ue~delyrwdforob~etricnn~bsdaYetpublLhaddata

concerning the maternal pharmacnkinetica of LAa remaina sparae. The few human #tullea published have

all involved either maternal venoau blood aamptig or multiple patient. dngle point determinntiom of

matermel arterial LA blood concentrations. Venau blood samplw nmy provide an unreliable estimate of

drug ooncentntiona that - on the arte&I side of the cimhtion. supplying the brain and heart.

Multiple patient sing&e point arterial determinations ara also ondependable. This study investSgates the

pbannacokineticd of lidocaine given epidvrally for cenremt Zion.

Methods. Ten healthy, pregnant women underSuing elective cesarean section were investigated

with IRB appmval andwith their written. informed ccmaent. Before inducingepidunl anesthesia, a radial

artery cannula (20 fg) WM inserted under local anesthesia, and a baseline arterial blood sample was teken. Lidoczdne 2% with epinephrine 1 in ZOO,OSO PN admkdstered incrementally every 3.5 minutes through

an epidvral catheter to achieve B T&2 demmtomal level of surgical blockade. Maternal artarial (Ma)

blood samples were drawn every five minutes for the first hour and every 30 minutea for the n?maiader

of the study. usually of three to four hours in duration. Blood wea also drawn from theumbilical vein (Uv)

shortly after delivery. Lidocaine concentrations were determined using a modified gas-liquid

cbmmatagrapbic method.’

-

-

_-

- Remdts weight dose

kg mg mgkg

CLM 49 520 IO.6

RMB 83 480 5.5

JH 65 500 7.6

R.Js 91 565 6.4

GCS 77 360 4.7

LLB 66 400 6.1

AT 96 450 4.7

AM 70 340 4.9

PQM 17 380 4.9

BAC 65 360 5.5

tl/Z(betn) Cl/kg Vd(aren) peak level

min mllmin It. min uglml

10.3.8 6.01 1.97 35 10.36

121.4 6.44 2.58 35 5.09

125.1 6.24 2.27 40 6.59

116.9 5.97 3.22 35 7.31

89.3 4.63 2.77 30 9.63

95.7 9.43 4.49 35 4.53

107.0 6.04 3.76 15 4.86

109.8 6.13 2.71 30 5.66

114.2 5.69 2.66 35 5.21

156.1 6.44 1.56 20 4.49

A46

.542

.738

.339

.2SO

.524

.471

.353

.188

,361

mean 74.0 435.5 6.09 113.93 6.10 2.60 31 6.39 .430

se 4.16 24.4 0.55 4.09 0.36 0.25 2.3 0.65 .050

Discussion. Given the limited number of obserwtions in this pilot study, measured maternal

arterial Iidocaine concentrationa and the UviMa rstiw after epidwl injection were not necessarily dose

dependent and were not always predictable. Estimatu of vohme of distribution and plasma clearenco

adjusted for maternal body weight. wet-e campamble. Data collection using maternal arterial blood

sampling oontinuea so BP to confii or refute these initial findings.

References.

’ Tucker. G.T.: Determination of Bupivacaine (Mamaine) and Other Anilide-type Local Anesthetics in

Human Blood and Plasma by Gas Cbromatograpby. ANESTHESIOLOGY 32: 255, 1910.

44

-

-

-

Title: NEUROMUSCUL.AR BLOCEING PROPERTIES OF ORG 9426 IN POSIT’ARTUMPATIRNTS

Authors: JL Hawk@, MJ Rivers, RE Dalmeida, TH Joyce Afftliatton: Section of Obstetric Amsthesia, Baylor College of Medicine,

Houston, Texas 77030

Introduction Organon 9426 is a new reversible nondepohuixing neuromuscular blocking agent with properties similar to vecuronium. In surgical patients it has been shown to have a more rapid onset, producing satisfactory intubating conditions in approximately one minute. This pilot study was performed in patients undergoing postpartum tubal ligation within 48 hours of delivery to assess the neuromuscular blocking properties of ORG 9426 in this patient population and its potential effectiveness as a component of a rapid sequence induction.

Metho& Approval was obtained from the appropriate Institutional Review Boards and 13 patients scheduled for postpartum tubal ligation were studied. After premeditation with cimetldine 300 mg PO, metoclopramide 10 mg PO, and sodium citrate 30 cc PO, anesthesia was induced with fentanyl3 mcg/kg and thiopental3 mg/kg IV. A baseline twit& was recorded and followed immediately by ORG 9426 600 mcg/kg (2xED95). Patients were ventilated with oxygen until the twitch height was reduced by 80% or more, then laryngoscopy and endotracheal intubation were performed. The times from administration of ORG 9426 to 80% suppression, 100% suppression, intubation, 10% recovery, and 25% recovery were recorded as well as intubating conditions. ECG and oxygen saturation were measured continuously and blood pressure was rewrded every one minute. Neuromuscular blockade was measured by the response to ulnar nerve stimulation at the wrist using surface electrodes. The response was measured using an Adductor Pollicis Monitor (Cedar) and recorded on a direct writing oscillograph.

The onset Results: The mean time to 80% twitch suppression was 38 seconds. time (100% suppression) was 102 seconds. Intubating conditions were good or excellent in all patients. Times to 10% recovery and 25% recovery (clinical duration) were 42 and 50 minutes respectively. Neuromuscular blockade was successfully reversed in all patients. There were no adverse hemodynamic responses or alterations in oxygen saturation in any patient. ‘Iwo patients, both smokers, had treatable bronrhqasm after intubation.

MEAN ss! w 38 11 26-67

100% SUPPRESSION 102 38 46-161 10% RECOVERY 42 13 25-72 25% RECOVERY 50 15 30-88

Discussion: In this group of postpartum patients undergoing tubal ligation, ORG 9426 provided a rapid onset of neuromuscular blockade and minimal cardiovascular side effects in a dose 2xED95 (600 mcg/kg). The rapid rate of development of neuromuscular block may make ORG 9426 a viable alternative when rapid sequence induction using a nondepolarizing rekurant is d&able.

Referenres; 1. Wierda JMRH et al. Br J Anaes 64:521-523,199O. 2. Mayer M et al. Anesthaviology 75tA1070, 1991.

45

_

-

.-

-

Title: Ilioinguinal Iliohypogasnic Nerve Blocks-Before or After Cesarean Section? Authors: HJ Huffnagle, DO, BL Leighton, MD, MC Norris, MD, VA Arkoosh, MD AffRiation: Depamnent of Anesthesiology, Thomas Jefferson University, Philadelphia, PA

Introduction: Bilateral block of the ilioinguinal and iliohypogastric nerves (IINB) at the anterior superior iliac spine provides analgesia in the Lt dermatomal distribution. Since the Pfannenstiel incision lies within this dermatome, postoperative IINB provides analgesia after cesarean section for up to 24 h .1 Preoperative local anesthetic infilnation or IINB signifi- cantly limits post-hemiotmphy pain for up to 10 days.**3 We designed this randomized double blind study to compare the analgesic effect of IINB placed before or after cesarean section under spinal anesthesia. MethodS AfraapprovalbyoUrIRB,~~~~~~~~~~~~y,n~- laboringtennpamnientsscheduledforelcctivecesarean ztionviuPfannenstielincision.Weind&

of the following groups: After - IINB placed after cesaxan section but befne reg~~~Gon of spinal blockade;Befoxe-IINBplacedafterspinal blcckadebutbeforeincisionncision;axlNonc-no nave block The blocks were performed b&temlly using 10 mL 05% bupivacaine with 15X0,000epinephrine.3 Intravenous morphine,tiFCApump,providedaddi- tionalposropaadveanalgesia_We& iIl&iOMIandOV~painatreSrardWith

movementusing lmma&ed10cmvisual analoguescalesat6,12,24,48,and% hours post induction. We analyzed pain saxe and morphine consumption data us- ing the Kmskal-Wallis test Resufts: The3gmupsdidnotdif- fa in age, height, weight, or p~vious numbzrofcesaxan sections. Patients in the two IINB gmups consumed less mor- phinethanunblozkedcontmlsat~,4-8 and20-24hafterstqery(figurel).Pa- tients who had IINB placed postopem- dvelyhadhigberpainsat24h(over- allnxandmovement)and48h(iicisional movement, ovetall xst and movement) (figure 2). Diion: Nerve blocks placed af- tcrcesanxnsectionprovidedearlyanalge- sia;however,wcmenrepntedmozepain than unblocked controls after the block

Figure 1 + Alter

a- Before

-A- None

’ ’ ’ ’ ’ I 0.4 4-8 8.12 12-16 16.20 20.24 Time after Induction of Aaesthain l.X)

20 -U Ak Figure 2 -0- Before

16 4 Nme

z 14 l p < 0.05

IE~E.S& As in nonpregnant @en&~ the pain sparing effects of blocks placed before skin incision p&stedthmughoutthepostopuadveperial. Referencex 1. Br J Anzsth 1988;61:773., 2. Anesth Analg 1990;70:29., 3. Reg Anesth 1990;15:130.

46

-

-

._

.-.

.-

.-

_-.

-

_-

Title: Do Patient Variables Influence the Subarachnoid Spread of Hype&ark L&wine in the l&+rtum Patient?

Authors: ~.H~ele.D.O.,MCNorris,~.,B.LLeighton,~.,V.k~~,MD., HJ. Hufhragle, D.O., S. Sharkey, MD.

‘4RXatIott: Department of Anesthesiology, Thomas Jefferson University, Philadelphia, PA

Introduction: Age, height, body mass index (BMI), and vertebral column length, have been suggested as variables that influence the extent of sensory blockade after subarachnoid injection of local anesthetics.1 Recently, Norris found no correlation between any of these variables and the spread of hyperbaric bupivacaine in the term partutient.2 We wished to further evaluate this question by studying a different local anesthetic (hyperbaric lidocaine) in a different patient population (postpartum women). Methods: Wi~~hoursofuva~~~v~,~ASA~I~~~tf~~ agreeing~ospinalaf~p~~veor induction, we weighed the patient aral measumd her height and vertebral column length (C7 - sacml hiatus).SpinalanesthesiawasinducedattheL2_3orL3_4interspacewiththepatientintherightlataal decubitusposition.Weinjected75mg5%lidocainewith7.5%dexaosewimoutb~epatients were then positioned supine. An observer, blinded to the measured variables, evaluated loss of tempemt&emationandlossofsensa- tion of sharpness to pinprick bilaEmUy every5minutesfor3ominutesand againat45and6ominute.s.Weused linear regression analysis to look for anrelations between the spread of sen- sory block at 30 minutes (time of maxi- mum spread) and age, heighs weight, BMI and vertebral cohmm length. Results: See fable and figure. Discussion: Previous reports have examined the influence of pa- tient size on the subarachnoid spread of local anesthetics in pregnant and nonpregnant subjects19 This study considers a third group of patients. Postpartum women exhibit an inter- mediate sensitivity to neuraxial lo- cal anesthetics. As in parturients,2 age, weight, BMI and vertebral col- umn length do not correlate with the extent of sensory block. Height ac- counts for < 20% of the variance in the spread of sensory block. Given

Variable

Age W) Weight (kg)

t

Height (cm)

BMI (kgAn2)

Vertebral Column Length (cm)

the large variation in spread within patients of the same height, attempting to adjust the dose of drug injected by height seems of little practical use. References: 1. Anesth Analg 1985;64:715., 2. Anesthesiology 1990;72:478.

47

-.

.-

._

-

-

-.

Tide: DOES EPHEDRINE REMAIN THE VASOPRESSOR OF CHOICE FOR TREATMENT OF HYPOTENSION DURING RITODRINE INFUSION AND EPIDURAL ANESTHESIA?

Authors: M&r&_&&* Chestnut DH, Vincent RD. Sipcs SL. DeBmyn CS, Atkins BL, Podoska DJ. ChaaRjeeP

Affiliation: Departments of Anesthesia and Obstchics and Gynecology, University of Iowa College of Medicine, Iowa City, IA 52242

m. Pattorients who have failed ritodrine. tocolysis often become candidates for epidaral anesthesia. Earlier, we hypothesized that in a patient or animal already receiving a B-agonist. any vasopressor effect from ephedrine would result from a-receptor stimulation. The accompanying uterine vasocooshiction might fttrthex deawse uterine blood flow. However, we observed that ephedrine restored uterine blood flow velocity (UBFV) daring hemorrhagic hypotension.’ and ephedrine, but not phenylcphrine. preserved UBFV daring ritodrine infusion2 in gravid guinea pigs. However. neither smdy evaluated fetal oxygenation or the treatment of hypotension during regional anesthesia. Tbe purpose. of this study was to determine whether ephedrine [r phenylephrine is mare appropriate for treatment of h-tension dating epidtral anesthesia and ritodrine infusion in gravid ewes.

&g&&. The protocol was approved by the Animal Care Committee. Experiments were performed in fourteen chronically instrumented ewes Ween 0.8 and 0.9 of timed gestation. ‘Ihe protocol included the following: 1) 60 minutes for baseline measurements; 2) at time zero. start of ritodrine infusion at 0.002 mg/lrglmin; 3) at 120 minutes. epidaral injection of 2% lidocaine to achieve a sensory level of approximately T+ 4) at 135 minutes, bolu administration of ephedrine 2.5 mg, phenylephtine 50 pg. or normal saline (IiS) 2.5 ml, followed by intravenous infusion of the same agent for 30 minutes. In the ephedrine and phenylephrine experiments, the infusion of vssopressor was adjusted to maintain matcmal mean arterial pressure (MAP) as close as possible to baseline. In the control experiments, the animals received NS at a rate of 2.5 ml/m& and there was no other effort to restore MAP to baseline. Statistical analysis was by repeated measures ANOVA. P co.05 was considered significant.

Beyllrs. At 120 minutes, maternal heart rate (I%) was approximately 135% of baseline in each of the three groups. Maternal HR decreased during epidwal anesthesia in all three groups. Both ephedrine and phenylephrine restored matemal MAP m baseline, as designed in the study protocol. However. ephedrine restored both matcmal UBF and fetal p9 to baseline. whereas phcnylephrine did not.

110, 110,

m. Ephedrine was superior to phenylephrine in restoration of UBF and fetal pO2 during ritodrine iofasiin and epidmal anesthesia

Refennces. 1. Chesmut DH. et al: The effect of ephedrine upon uterine artcry blood flow velocity in the gravid guinea

pig subjected to terbutahe infusion and acute hemorrhage. Anesthesiology 66~508-512.1987. 2. Chestnut DH, et al: The effect of vasopressor agents upon uterine artery blood flow velocity in the

gravid guinea pig subjected to ritodrine infusion. Anesthesiology 68~363-366.1988.

Supported in part by NIH GM40917

48

_

-

TITLE: EPIDURAL CATHJXERS GONE ASTRAY: CAN THEY BE SAVED?

AUTHOR:

AFFILIATION:

Aaron Stein, M.D.*

Department of Anesthesia, Wake Forest University Medical Center, Winston-Salem, North Carolina

brtroduction: The likelihood of “succesful rescue” of complete or partial unilateral or patchy epidural blocks for labor by withdrawing the epidural catheter a small amount has not been documented. As a result, the decision whether to attempt this maneuver or simply insert a new catheter may be clear to the clinician, while appearing arbitrary to an unbiased observer. We therefore undertook a retrospective chart review to determine what percentage of labor epidurals which were initially one sided could be made functional by manipulation and if any patient characteristics or epidural catheterization variables might be useful in predicting this outcome.

The records of all patients receiving epidural catheters for labor for the Methods months of October and November 1991 were reviewed and a questionnaire was kept with the epidural trays in an attempt to evaluate all inadequate labor epidurals. All epidurals which were manipulated to correct a “one sided catheter” were included in this study. Manipulated catheters which were subsequently dosed for delivery or cesarean section before they could be proved adequate for labor were excluded. We recorded depth to the epidural space from the skin catheter distance in the space, distance catheter withdrawn during manipulation, final depth at the skin, patient height and weight, original block level, final level, nature of discomfort and final disposition of the catheter. Data are expressed as mean SEM and were analyzed by t-tests.

Of the 500 labor epidurals during the 2 month study, 100 (20%) were one Results: sided. Of these 100 one sided blocks, catheter manipulation solved the inadequacy in 67 and failed in 33. Of the 33 uncorrectable blocks, 24 were eventually replaced, with 8 of these (33%) failing to function properly. Three of these were replaced yet again and ail 3 functioned well. Examination of the 67 originally “saved” and 33 “failed” catheters revealed no difference in patient height, weight, body surface area, or depth to epidural space. However initial distance in the epidural space (3.8 2 0.1 cm in the “saved” group v0su.r 4.4 2 0.4 cm in the “failed” group) was almost significant (p = ,056).

Discussion: Based on a chart review of 500 epidural catheters placed for labor, it appears that 67% of the one sided catheters can be salvaged by manipulation. These data suggest that one sided blocks may be more likely with increased length of catheter in epidural space, prompting design of prospective studies to evaluate the effect of catheter length in the epidural space on catheter success.

-

-

49

-

TM: Potential Metal Particle Contamination of Epldural and Subarachnold Spaces Using the Needle-Through-Needle Technique

Author:

Afflllotlon:

Molln JD’, Knape KG’. Husaln FJ’

Department of Anesthesiology, Wllford Hall USAF Medlcal Center’; Department of Anesthesiology, Unlverslty of Texas Health S&me Center.

San Antonlo. TX 78284

It$-TR DU ION. Recent concern has been raised regardlng the POtentId for metal + pa c e contamination of the epidural and subarachnold spaces resultlng from needle lumen abrasion while performlng a combined splnal-epldural block using the needle- throu

B h-needle technique.(‘) This study was deslgned to evaluate whether needle

abrason wlth resultln R

metallic particles occurs using recently Introduced atraumatlc splnal needles throug Tuohy or Hustead epldural needles.

METHOD: This study evaluated two 17- and five la- gauge Tuohy-Schliff and two la- mustead epldural needles (Burron Medlcal Inc) before and afler passage of a s 4 gauge x 120mm Sprotte splnal needle (Pajunk). uslng the following protocol: 1) Each epldural needle was examlned mlcroscoplCally (100x) and photomlcrographed (45x). 2) The epldural needle was subsequently flushed wlth 0.5~~ fliiered. sterile water which was saved for later mlcroscopy. 3) Afler drying. a new splnal needle was passed once through each epldural needle to O.acm beyond Its tip and removed while the epldural needle tlp was wlthln the 5cc Well of a tls.%Je cutture tray to collect any resultant particles. 4) The epldural needles were agaln flushed wlth 0.5~~ of water. 5) All flush samples were evaluated mlcroscoplcally (103x) for metallic particles. 6) All epldural and spinal needles were agaln examlned mlcroscoplcolly and selecthely photomlcrographed.

RESULTS: No metal particles were vlsuallzed microscopically In the water flush samples or the collectlon well uslng needle-through-needle protocol described above. The epldural needles each showed a very small defect at the inner edge of the bevel at the tip. but no evidence of chlpplng. A splnal needle was continuously observed posslng through an la-gauge Tuohy-Schllff needle at 100x magnlflcatlon. and no loose particles were produced, despite producing a defect slmllar to the previous epldurol needles. Mlcroscoplc evaluatlon of the Sprotte needles revealed fracture lines and/or minute chips at the tips. however these flndlngs were not different from slmllarly examlned unused Sprotte needles. manufacturing artifacts.

These observatlons probably represent When unused epldural needle tips were exposed to a

magnetic field. tlny metal portlcles were uniformly observed standlng out from the tip under lalx magnlflcatlon.

YF= Thls study dld not observe the productlon of metal particles after

pe ormlng the needle-through-needle technique. In contrast to the flndlngs of El&r and

Erodsky.0 The presence of an epldural needle tip defect after splnal needle passage observed here In the absence of metal particles probably represents an Inherent malleablllty of the epldural needle metal and not the loss of mass, It is unclear which type Of splnal needle Eldor and Brodsky utlllzed In thelr report, but It Is likely they used a Qulncke-tlp needle. Perhaps this tlp Is more damaglng to the epldural needle lumen than the Sprotte needle used here, and may explain the productlon of metal particles In their study. Metal particles appear to preexlst In all epldural needles and do not oPPear to represent needle damage but ore likely the result of the manufacturing Process. However. these oartlcles are not liberated by the Injection process.

REFERENCES: 1) Eldor J. Brodsky V: Acta Anaestheslol Stand 35: 461, 1991.

-

-~

50

-.

-

Title: Utb0rS: Affiliation:

IuKEPmT0FnA0iE9IDRoNCOCbMBluMcIlY S,, J. Horn, G. Sinqh, V. Jauson, R. Johnson, B.V.R. Sastry, JR. Xanbas Vanderbilt UniversiQ Schwl of Medicine Department of Anesthesiology, Nashville, TN 17232

Raquesiun sulphate infusion is frequently used in pregnant patients with pregnancy-induced hypertension or Intrcdwtion: toxemia. Cocaine toxicity can induce hypertension and/or conmlsion. In pregnant patients it is possible that a magnesium sulphate infusion could initially be used to treat hyperteosion in a cocaine-toxic patient. Calcius channel blockinq aqeots have been suggested to reduce cocaine toxicity (1). Kaqnesius is krm to have sane calcius-channel blockinq properties. The purpose of this study uas to investigate vhether aaqnesiuu sulphate alters cocaine toxicity. @&: The approval of the institutional Animal Care Con&tee was obtained. 73 adult sale Spraque-Dauley rats weiqhinq 250-300 q we randouly divided into 4 qroups. me rats were anesthetized vith 50 aq/kq of intraperitoneal pentobarbital hydrochloride. A femral vein vas cannulated for drug administration. A preliminary dose raspanse experiment using IO- 14 nq/kq of intravenous cc&e ws perforned to assess the toxicity of cocaine in the rat. Based on this experinent, 12 nq/kq cocaine dose was chosen for intravenous injection. A naqnesiun sulpbate dose of 50 aq/kq uas used for the pretreataent agent. The naqnesiuu sulphate dose uas reduced to 40 nq/kq in a second experinent. Rats in Groups I and II received pretreateent with either norsal saline or saqnesiue @hate 50 eq/kq in equal volume over a period of one minute. Pive ainutes follminq the pretreatient aqent, all rats in Groups I and II received 12 nq/kq cccaine over 10 seconds. lhe sase protocol for rats in Groups III and IV MS followed except that a 40 sq/kq dose of magnesium sulphate MS used. The experiments we perforeed betveen 9:OO a-u. and 12 nwn to avoid diim?ai variation. Respiration, heart rate and rhytha vith ECG lead II we monitored throuqhout the experiaent. The rats were not ventilated or oxyqenated to mimic the usual

clinical situation of cocaine toxicity. Rats vere classified as survivors or fatalities at 10 minutes following the

adsinistration of intravenous cocaine. The rats that maintained adequate ventilation, rhytim and heart rate vere classified as survivors. The rats that developed apnea, cyanosis, and aqonal rhyths vith no cardiac inpulse were classified as

fatalities. &&: There were no significant differences in fatalities in either of the tw Xaqnesiua qroups or when both groups we cosbined for statistical analysis. (pvO.05, Chi-square, Escher’s exact test). Fatalities developed apnea, cyanosis, and aqonal rhythm with no cardiac impulse.

Table I Table II Cosbined data for Rat treated rats

01 1%) Group n Pretreatment Fatalities Fatalities croup n Pretreatsent Fatalities Fatalities

I 11 Saline 9 82 A 37 Saline 24 65 II 9 Rqf 50 Wkq 5 55 R 36 Raonesius I4 38

III 26 Saline 15 58 IV 24 Rat 40 so/kg 9 38

&Q&&E Recently, Nahas suqqestad that selected calciuu channel antaqonists say be sore effective antidotes than alpha or beta adrenerqic blockers in the treatment of the cardiovascular toxicity of cocaine (1). Raqnesiun has been shown to

be as effective as propranol and sore effective than verapil in controllinq the arrhythmias associated vith epinephrine administration (2). Cocaine produces elevated levels of catecholanines by activation of the central nervous system which results in an increase of syapetbetic - adrenal aedullaiy discharge (Il. Serus saqnesiuii levels exceedinq 2.5 naol/l

produce prcqressive inhibition of the release of catecholanines from both adrenerqic nerve terainals and free the adrenal nedulla (4). Pretreatsent uith naqnesiua sulphate say have improved the survival rate of cocaine adainistered rats. (~~0.1) However, the conperison betwen the groups is not significant at p=O.O5. Raqnesiua sulphate does not increase cocaine toxicity in the rat. Further investiqation is under uay to confirs these prelisinary results. References: 1. Nahas: TreatPent of Cocaine-induced cardiovascular toxicity (letter to the editor) Anesthesioloqy; 15:544,1991 2. Wayer DB, Uiletich D, et al. The effect of saqnesiue salts on the duration of epinephrine-induced ventricular tachyarrthynias in anesthetized rats. Anesthesioloqy; 71:921-928,1989. 3. Chiueh C. Kopin I. Centrally mediated release by cocaine of endoqenous epinephrine and ncrepinephrine from the syPpathoadrena1 nedullary systes of unanesthetixed rats. Journal of Phars Rx-p Ther Vol 205 I1 p. 148-154, 1990. 4. James, Il. Clinical Use of Haqnesius Infusions In Anesthesia. Anesth-Analq, Vol 74:129-136,1992 Supported by the Study Center of Anesthesia Toxicoloqy, Vanderbilt University Mica1 Center, Nashville, Tennessee

-

-

TITLE: A COMPARISON OF BOLUS INJECTION VS. CONTINUOUS INFUSION OF LIDOCAINE DURING CESAREAN DELIVERY

AUTHORS: Naulty JS?Dominguez J

AFFILIATION: Department of Anesthesia George Washington University, Washington DC.

Epidural anesthesia is frequently employed for cesarean delivery. Typically. this technique involves the injection of a b&s of local anesthetic at dte initiation of the procedure, followed by supplemental bolus injections as necessary to maintain the anesthetic during the procedure. Continuous epidural infusions of local anesthetics are employed in other settings to maintain anesthesia but we could not find any infomtation regarding the use of this technique during cesarean delivery. Therefore. we have performed a double-blind. randomized study of this technique in patturients at at* institution.

The protocol was approved by the hospital’s Committee for the Protection of Human Subjects and written informed cottsent was obtained. We have studied 27 ASA class I multiparae who were scheduled for elective. repeat cesareat delivery. Epidural anesthesia was established in our usual manner for elective cesarean delivery, using 2% lidocaine with epinephrine 1/200,000 to which 2Spg/ml fentanyl and .lml NaHCqi / ml had been added. The patient was taken to the operating mom when anesthesia to the sixth tboracic detmamme had been established, and the operation begun. ?ix patients were randomized into three groups. One group received a repeal bolus of 10 ml of the same local anesthetic solution 45 minutes after the initial injections had been completed as is our usual practice. The second group received 10 ml of the same local anesthetic solution when 2 segment regression of the highest sensory level was noted. The third group received a contittuous infusion of 7 ml/ hour of 0.5% lidcaine with 2.5 pglml fentanyl during the operative procedure. Tlte infusion was discontinued at the time of fascial closure. During the procedure and in the recovery room. sensory levels.vitaJ signs and visual analog pain and motor block scores were recorded at frequent intervals. Umbilical blood gases and Apgar scores were obtained at delivery. Tne patient was observed in the recovery area for 2-3 how.. and transferred to the adjacent postpartum area following recovery from tbe anesthetic. Epidural fentattyl was used following regression of motor block for postoperative pain cootml. All the patients were seen 24 hours following the discharge from the recovery room. The time to first narcotic. presence or absence of pnnitis. ttausea or vomiting. and bladder dysfunction were recorded. Non-parametric observations were statistically analyzed using contingency-table analysis. and parametric saxes were analyzed using multiple analysis of variance. Results

The mean duration of cesareatt delivery in this study was 93 f 15 mimttes. Patients who received bolus injections following 2 segment regression bad a significantly increased incidence of intraoperative pain wxes > 0, as compared to patients who received timed boluses or cotttinuous inhtsion..(fig I) Patients who received continuous infusions of lidocaine received significantly less local anesthetic during the procedure than either of the other techniques. Patients who received continuous infusions of lidocaine had a significantly more rapid recovery of motor and sensory funcdon following cesarean delivery. (fig 2)

-

.-

.-

-

.-

100

80

60

40

20

0

Conclusions We conclude that .a continuous infusion of O.S% lidocaine during cesarean delivery provides excellent

analgesia with significant decreases in local anesthetic dose and motor block.when compared with bolus supplementation.

52

-

-

-

_

-

-

.-

-.

_

Title:

Authors: AfTiliation:

Altered Heart Rate Response to Hypoxia in Women Who Develop Preeclampsia SK Palmer. MD; JC Berman, MD; S Zamudio, PhD; CP Gibbs, MD; LG Moore. PhD

Departments of Anesthesiology, Cardiovascular Pulmonary Research, and Anthropology; University of Colorado Health Sciences Center and Denver Campus

Introduction; We have previously observed’ a high incidence of preeclampsia at high compared with low altitude. Residents at high altitude. provide a natural shldy population for examining the factors which are associated with developing preeclampsia. We sought to determine whether preeclamptic women have greater heart rate and blood pressure responses to acute hypoxia than normal women and, if so, whether

increased responsiveness was preserved postparhtm. Twenty-six healthy residents of 3100 m (Leadville, CO) at no known risk for developing Methods:

preeclampsia were studied at weeks 24 and 36 of pregnancy and 4 months postpartum. Five of the 26 subjects (19%) became preeclamptic (2 or more blood pressures 2 140190 mmHg with > I + proteinuria or other organ system involvement) while 21 remained normal. More of the preeclamptic than the normal women were primiparous (4/5 vs. 7/21, p<O.O5), but othenvise they were similar in age, height, weight, weight gain, education, smoking history, and number of prenatal visits. We measured heart rate, blood pressure (Finapres, Ohmeda), and end-tidal PO2 (Applied Technical Products) during 7-10 min of acute, progressive isocapnic hypoxia. Data from the Finapres (2-set intervals) was merged with continuous measurements of end-tidal PO1 to calculate the heart rate and blood pressure responses to hypoxia.

Resultci: In the normal women, acute hypoxia increased heart rate 24+ I bpm and mean arterial blood pressure 9*2 mmHg while pregnant and postpartum. The preeclamptic women were studied prior to the onset of hypertension and diagnosis of preeclampsia. They evidenced a greater heart rate response to acute

hypoxia while pregnant than the normal women, and their increased responsiveness was preserved postpatim (Figure). The rise in mea alterial pressure was greater in the preeclamptic than the normal women while pregnant (l7i3 vs. 9+2 mmHg) but not postpartum (9+2 vs. 9*2 mmlig).

140 PREGNANT POSTPARTUM

Heart 120 /.-. + preeclsmpsia 1

Rate (bpm) 100 /.’

i

p<.os

,/’

80 /

normal

60 i

80 40 End-tidal PO, (mmHg) 80 40

Discukn: We found that the heart rate and blood pressure responses to acute hypoxia were grester in preeclamptic than normal women and that the increased heart rate response was preserved postparmm. Increased cardiovascular responses have been observed previously in women who will develop or already show symptoms of preeclnmpsia a’ but. to our knowledge, this is the first report of increased responsiveness to acute hypoxia and of the preservation of the increased heart rate response postparmm. Further studies are warranted to determine whether increased autonomic responsiveness to hypoxia CM be wed as a diagnostic test to identify women likely to develop preeclampsia.

References: 1. Moore LG, et al. The incidence of pregnancy-induced hypertension is increased among Colorado residents at high altitude. AJOG 144(4):423-9, 1982.

2. Gent NF. et al. A prospective study of angiotensio II pressor responsiveness in pregnancies complicated by chronic essential hypertension. AIGG 1273369-375, 1977.

3. Leighton BL, et al. Pre-eclamptic and healthy term pregnant patients have different chmnotropic responses to isopmtereaol. Anesth 72392-393. 1990.

4. Wouters EJM, et al. Autonomic heart-rate control in response to standing in toxemic and normotensive primigravid pregnancies. Eur J Ob Gyn Repm Biol 16:309-314, 1984.

53

,-

-

-

-

-

.-

.-

_

.-

Title: Maternal age in Primigravidae as a factor in obstetric outcome.

Authors: pate1 N. Morgan B. Affiliation: Queen Charlotte's and Chelsea Hospital, London.

Introduction. A feature of social change in Europe is the voluntary postponement of childbearing [l].The anaesthetic and obstetric implications of such delay has not being fully elucidated.

Methods. A retrospective study of 5515 consecutive primiparaa with term singleton cephalic infants was undertaken. We report epidural analgesia rate and mode of delivery as related to maternal age.

Results. Table 1 gives details of the whole age group and that of women at the outer age limits.

Table 1 Total Age Age Population c20 >40

Total Number n(o) 5515 284 (5) 140 (2.5) Elective Caesarean Section 264 2 35 Number in Labour 5251 282 105 Emergency Caesarean Section n(%) 627 (12) 22 (8) 24 (23)* Instrumental Deliveries n(%) 1867 (36) 54 (19) 51 (49)* Epidural Analgesia n(%) 3104 (59) 134 (48) 77 (73)' NO Intervention n(%) 1707 (33) 132 (47)_ 17 (16)*

* PeO.05 between groups. ‘isure 1

AgeDisaibutionOfPrimagravida Effectofageonintenrentionrates.

_ Family policy bulletin ( Aug 1991 ). Family policy studies centre UK.

1.

2.

3.

Report on confidential enquiries into maternal deaths in the UK 1985-1987. London HHSO 1991. Hansen JP. Older maternal age and pregnancy outcome: A review of the literature. Obstetrical andGynaecologica1 survey 1986.41(11) 726-42

DiscusEion. National Figures in the UK between 1985 and 1987 show that only 15% of primiparae were over the age of 30 121. This obstetric unit with 45% primiparae over the age of 30 indicates the future obstetric and anaesthetic workload associated with rising maternal age. This will have financial implications for obstetric units as the level of staffing and the quantity and quality of equipment for monitoring mother and fetus will need to be reassessed, as the complication rate increases with age [3]. Furthermore, it is apparent that if reliable comparisons of obstetric outcome between countries and units are to be made, demographic details of the population concerned must detail the number of primiparae over 30 years of age rather than the mean age. Only 16% of women over the age of 40 delivered without any obstetric or anaesthetic intervention, and we as physicians need to be aware of these findings in order to adequately counsel them.

References.

54

-

-

m Protein Binding During Pregnancy

Puthors; Rosinia F, Bader AM, Fragneto R, Arthur GR, Datta S

Affiliation: Department of Anesthesia, Harvard Medical School Brigham and Women’s Hospital, Boston MA

Introduction: Sensitivity to local anesthetics may be altered durfng pregnancy. Decreases in protein binding may in part explain the higher incidence of toxic reactions in pregnant women at term. Previous studies have compared protein binding in term patturients to a group of nonpregnant controls (1). The present study attempts to determine protein binding throughout gestation to determine the pattern of changes that occur. Methods; Approval was obtained from the hospital’s Human Subjects Committee. 46 parturlents at various stages of gestation and 6 non- pregnant controls were enrolled. Plasma samples were stored at -20 C after centrifugation. A lidocaine concentration of 2 micrograms per ml was used. Samples were analyzed using a gas chromatographic technique to determine the free fraction of lidocaine. The free fraction was taken to be a meaure of in vitro binding. Free fraction was plotted versus gestational age and a correlation coefficient obtained. Results: The free fraction of lidocaine increased significantly throughout gestation, reflecting a corresponding decrease in protein binding (See Figure). Discussion: A decrease in protein binding throughout gestation is seen to occur. This may in part explain the increased sensitivity of the parturient to local anesthetics and may have implications when regional anesthesia is used for surgery during pregnancy. Reference: (1) Wulf H et al. Acta Anaesthesiol Stand 1991;35: t29- 33. 100‘

00 - w? 10.170: P < 0.005

80 -

-

.-

.._

_

-

-

-

-

-

.-

-

_-~

-

-

Title: Concentration of Pentanyl in Colostrum after an Analgesic Dose Authors: Steer PL, Biddle CJ, Harley WS, Lantz RK, Sulik PL Affilation: Department of Anesthesiology, University of Kansas School of

Medicine, Kansas City, KS 66160

Introduction. Pentanyl is frequently used in providing analgesia or anesthesia to women during the postpartum period. Although manmary excretion of other anesthetics and analgesics has recently been studied. the excretion of fentanyl into breast milk has not been examined(l). Postpartum women who have had anesthesia often inquire about the amount of drugs transferred to their newborns through their breast milk. Since this is a camnon concern the purpose of this study was to measure the concentration of fentanyl in human colostrum after intravenous administration of an analgesic dose.

Methods. Thirteen healthy women were given fentanyl 2 ug/kg for analgesic supplementation during either Cesarean section (n-8) or postpartum tubal ligation (n=5). Blood and colostrum samples were taken at 45 minutes, 2. 4, 6, 8 and ten hours following administration of the drug. Serum and colostrum samples were analyzed for fentanyl by solid PhSSS radioinmunoassay and validated by gas chromatography/mass spectrometry.

Results. Radioirmmxuxssay showed that fentanyl appeared in colostrum. The hinhest concentration of fentanyl in colostrum was at 45 minutes, the initial sampling time, reaching O-40 f 0.059 ng/ml and the concentration was virtually undectectable 10 hours later. Serum concentration was also maximal at 45 minutes reaching 0.19 f 0.019 ng/ml. Pentanyl became undetectable in the blood by two hours after administration. Figure 1 shows the decay of fentanyl in serum and colostrum over time. FEHTIW"LCONCENTRIIlON,np,.l,

0 I n:, OF COUTmvi ,h&, 10 12

Discussion. This study showed that fentanyl does appear in colostrum after an analgesic dose. Neonates consume very little colostrum in the first few days of life, therefore the amount of fentanyl a neonate is likely to receive is extremely small(2). With these small concentrations intravenous fentanyl analgesia may be used safely in women who are breast- feeding full-term infants. 1. Fri!btrg YI, lortngorg 3, Chris:ensen Cl, et-al. Exrrtion of norptim in hum breast lilt. u Anrtrtberio! Sean? 19!9;33:626-8. 2. Atkinson BC, gegg C!, Darlor EA. Drugs in huna mild. Clinical pharmacokinetie conside:ations. Clin Pharmco! 1988;11:211-40.

56

-

_

.-

_.

-

Title:Thrombelastography and Sonoclot Analysis in the Healthy Parturient Authors:Steer PL, Krantz if Affiliation: Departments of Anesthesiology and Gynecology and Obstetrics, University of Kansas School of Medicine, Kansas City, KS 66160.

Introduction. High-risk obstetrical patients often need a rapid and complete coagulation assessment. Situations where this may occur are in pregnancies complicated by disorders such as pregnancy-induced hypertension, placental abrupt&, and idiopathic thrombocytopenia. Informs&x obtained from coagulation studies in these situations helps form obstetrical and anesthetic plans. Thrombelastography (TEG) and Sonoclot analysis ara whole blood viscoelastic coagulation tests that can provide complete and reliable qualitative coagulation data at the bedside in less than 30 minutes(l.2). To provide information to the clinician the values of these tests should be compared to the healthy parturient. Norms1 values have not been established in the parturient. Because the pregnant woman becomes hypercoagulable as gestation progresses, the TEG and Sonoclot analysis of the healthy parturientmay be different from the healthy non-parturient(3). This study was conducted to sea if there was a difference.

Methods.The protocol was approved by the Humsn Subjects Cwmittee. 4cc of whole blood was drawn from 7 women admitted to the obstetrical suite in labor with uncomplicated full term pregnancies and no previous history of coagulopathies and from 16 non-pregnant healthy volunteers. Within two minutes of obtaining the blood, Sonoclot and TEG studies were performed. TEG tracings wara analyzed for R. K. RK, (II angle and MA values. Sonoclot tracings wara analyzed for onset, ratet, peak and rate1 values. Sonoclot and TEG values were compared~ between the healthy pregnant subjects and healthy non-pregnant volunteers (Tables I and II). Statistical analysis was by an unpaired t test. A p value <0.05 was considered significant.

Results. labia I SONOCLOT ANALYSIS (nun ! SEI)

Parturient(n:b) Non-Parturient(n:IS) on$et(:ec) 71.7 ! 7.0 11s f 5.2 rata l(Smm) 37.3 f 2.7 IS.7 f 0.9

petk(min) 4.5 f 0.5 5.9 f 0.2 rate I (km) 10.5 f 2.0 6.9 f 0.6 Ttble /I THROtlBELASTOQRAPHY ANALYSIS (mean ! S9l!l

Prrtnricol(a-7) lwPururitnr(n:l6) aA(w) 71.3 f 2.3 59sj'*$l~ l(liaJ 5.3 f 1.3 . .

P(O.01 pa.01 P(O.01 KO.05

P(O.01 P(O.01

II(&) 7.6 ! 1.6 13.7 f 0.9 P(O.01 [(nip) 2.3 f 0.1 6.4 f 0.4 NO.01 D aall@ 6S.6 f 4.9 43.3 ! 2,s P(O.01

Discussion.Individual Sonoclot and TEG values are significantly different between the healthy parturient and the healthy non-parturient. The values found in the parturient reflect a hypercoagulable state. If these tests are to be used in obstetrical disorders with possible coagulopathies they should be compared to the healthy parturient as opposed to the healthy non-parturient.

I. Spiasr 90, lvankovich AD. cardiopuimonary bypasr.

lhrombociastography: A coagulation monitoring technique applied to In Effective Henostarir in Cardiac Sorscrv, N Elliron and OR Jobes adr. 1. 9.

Saunders Company, Philadelphia, 1988. 2. Shcnaq SA, ~aleem A. Vircoelartic flasrurement of Clot Formation: the Sonoclot. in Effectivb Hamottasit in Cardiac Surgery, N Ellison and DR Jobes sdr. X.S. Saunders, Philadelphia, 1989. 3. Batb.wa~ 118, Boaoar 3. Cosrolltion in Prcgnanr~. la Perinatal Couulation. SB Batharlr and J Boapar, tdr. Crone 6 Stratton, Yer lark, 1978.

-

- 57

__

._

-

EVALUATION OF THE POTENTIAL EMBRYO TOXICITY OF PROPOFOL USING AN IN VlTRO FERTlLlZATlON QlJALlTY CONTROL TEST (HAMSTER SPERM

MOTILITY ASSAY)

c Vincent RD. Hammitt DG, Rogers PR Institution: Departments of Anesthesia and Obstetrics and Gynecology, University of Iowa College of Medicine, Iowa City, IA. 52242

introduction The intravenous anesthetic 2,8-diisopropylphenol (propofol) is associated with rapid emergence and reduced postoperative emesis. Thus, it appears well-suited for short in-vim fertilization (IVF) procedures such as oocyte retrieval and pronuclear stage transfer. However, the potential toxicity of propofol on human oocytes and embryos is unknown. The hamster sperm motility assay has become the primary assay for quality-control testing in many IVF laboratortes. The purpose of the present study was to determine the effects of propofol on hamster sperm motility in vitro. Methods: The protocol was approved by the Animal Care Committee. Sperm suspensions obtained from male golden hamsters (n=18) were incubated in 2 ml of tap water (positive control), or 2 ml of artificial human tubular fluid (HTF) containing either propofol 2.5 pglml; propofol 5.0 l,tg/ml: propofol 10.0 pgglml; vehicle (Intralipid@) 1:2000 (concentration of vehicle used in 5.0 pg/ml propofol group); or HTF alone (negative control). The quality of motility was measured at baseline and after 8 h of incubation by a blinded observer as described by Bavister et al.’ (i.e., O=no movement; l=twitching, no forward progressive movement [fpm]; 2=slow fpm: 3=good, purposeful fpm; 4=rapid fpm without hyperactivation: and 5=hyperactivation with “figure of 8” looping movement). Sperm motility index (SMI) was calculated as follows: SMI=(grad& X % motile sperm. Statistical analysis was by paired t-tests. P-zO.05 was considered significant. m Data are presented as mean i SD. in the table.

Propofol 2.5 pg/ml 1178 f 118 Propofol 5.0 pg/ml 1170 -? 144 Propofol 10.0 pg/ml 1191 + 110 Vehicle 1:2000 1158 i 105 Positive control (tap water) 1088 * 139 Negative control (HTF) 1098 f 132

l PcO.05 versus negative control (HTF)

1898 + 153 1737 f 258 1381 *389* 1853 f 211

7f27’ 2000 ?: 125

Discussion: The hamster sperm motility assay is the most sensitive test used for quality control analysis in IVF laboratories. The assay is quicker and less expensive than mouse one-cell and two-cell bioassays.2 Rinehart et al.3 demonstrated that media known to result in lower pregnancy success rates for human IVF impaired hamster sperm motility but not the development of mouse two-cell embryos. Propofol concentrations which significantly impaired hamster sperm motility in the present study are higher than blood concentrations necessary to block autonomic responses during major surgery in humans (about 4 ug/ml).4 Also, because propofol is very lipophilic and highly protein bound, the bioavailability of propofol in viva may be less than concentrations used in this experiment. Although only the highest concentration of propofol significantly inhibited hamster sperm motility in the present study, additional studies are needed to help clarify whether propofol is a safe anesthetic lo use for women undergoing IVF procedures.

Referenca 1. Bavister et al. J Vitro Ferl Embryo Transfer 5:87-75.1988 2. Gorrill et al. Fertil Stetfl 55:345,1991 3. Rinehart et al. J Vitro Ferl Embryo Transfer 5:335-342,1988 4. Shafer et al. Anesthesiology 89:348-358,1988

58

TITLE: RITODRINR AND NITROGLYCERIN TOCOLYSIS AT CRSARRAN BREECH DELIVERY

AUTRORS: C. Wade, D. Barine, B.H. Rolbin', M. Oskamp, J.W.K. Ritohie

AFFILIATION: Department of Obstetrics and Gynecology, Department of Anesthesia, Mount Sinai Rospital Toronto, Canada.

__

_,~

. .

_

-

INTRODUCTION: The routine use of uterine relaxing agents at cesarean section for breech presentation under epidural anaesthesia has not been previously reported. Uterine relaxation for breech delivery may result in less traumatic delivery (l), however, uterine relaxation may result in excessive bleeding and the agents used may have maternal and fetal side effects. Our experience using these agents is presented.

MATERIALS AND METHODS: Institutional review board approval was obtained and all 284 caesarean sections for singleton breech under epidural anaesthesia, between July 1, 1988 to December 31, 1990 were reviewed. Ritodrine IV (1-1Omgs) was used in 67 cases and nitroglycerin (loo-1OOOpgs) was used in 22 cases, and no uterine relaxants in 195 cases. The tocolytic and control groups were similar in maternal age, parity, and neonatal birthweight.

RESULTS: None of the deliveries were complicated by intrapartum trauma. Uterine incision to delivery time was not significantly different between the ritodrine, nitroglycerin and control groups (Mean+SD: 2.Ok1.1, 2.7k1.9, 2.221.5 minutes respectively). The post-operative change in haemoglobin was similar (7.729.5, 9.5k8.9, 8.6+11.4g/L). No differences were observed in maternal pulse and blood pressure intraoperatively, and none of the patients required a blood transfusion. Furthermore there was no significant difference in neonatal outcome (Apgar score and NICU stay) between the groups.

CONCLUSIONS: This retrospective study does not support the routine use of tocolysis for breech cesarean delivery. However, we believe that ritodrine and nitroglycerin may be useful when delivery of the after-coming head is expected to be difficult. The data presented suggests the use of ritodrine and nitroglycerin for this indication is not associated with excessive bleeding or any other significant side effects or adverse reactions.

(1) Rolbin, SH., Hew, EM., Bernstein, A. (1991). Uterine relaxation can be life saving. Canadian Journal of Anaesthesia, 38, pp. 939-40.

59

-

_

_

._

_

._

Title: Statistical Process Control (SPC) in OB Anesthesia Service: Six Years Experience Authors: Paul Younestrom, M.D., David Boyd, AA., M. Frances Rhoton, Ph.D. Affiliation: Dept. of Anesthesiology, Case Western Reserve University, Cleveland, Ohio.

“When you can measure what you are speaking about and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory hind.” (Lord Kelvin, 1883) Retrospective anesthesia audits are (1) limited by the specificity of record entries, (2) often unable to provide incidence data, (3) time consuming, and (4) unable to provide on-going performance data. Smali-scaie experiments define differences between regimens in a con- trolled environment, but may not predict consequences for ciinicai practice. Demingl demonstrated the importance of SPC to these issues and quality improvement in manufac- turing and service industries. Since 1986, we have investigated application of SPC in ob- stetric anesthesia service, and report results from 15,847 consecutive anesthetics.

The anesthesiologist completed a checklist wncurrendy for each case. We previously described the mixed-agent, epidurai infusion used routinely.2 We used runs-based statisti- cal criteria to analyze monthly control charts (aggregate mean data are presented here).

ACTWIlT INDICES: OUTCOME INDICATORS: Obstetric Anesthetics = 15,847 Satisfactory Anesthetic Effect = 97.1%

By technique: Epidural = 85% Patchy or one-sided block = 1.8% General = 1% Local anesthetic toxicity = 0.05% Spinal = 0.6% Total spinal = 0.01% other = 1% other = 0.9%

By procedure: Vaginal bhth = 54% Uncomplicated Performance = 91.3% Cesarean birth = 29% Multiple level attempts = 4.0% D&C = 6% Blood return = 1.2% Other = 11% Unintentional dural puncture = 0.3%

Deliveries with Anesthesia = 63% Procedure abandoned = 0.2% Other = 2.9%

DEMOGRAPHIC MODIFIERS: Postanesthetic Complications = 1.2% Abnormal ASA PS (3-S) = 6.3% Complaint of epidural narcotic related pru-

5 minute APGAR < 7 = 5.5% rims, N&V = 1.2%

Preanesthetic Complications: Complaint of backache, temporary = 0.4%

Maternal = 24.6% Dural puncture headache = 0.2%

Preeclampsia = 18.4% Management: conservative = 41%

Morbid Obesity = l3.9% blood patch = 59%

Diabetes = 11.8% Neurologic scquelae (not necessarily anes-

Abruption = 3.9% thesis related), temporary = 0.1%

Fetal = 30.1% Delayed block regression = 0.1% Other = -z 0.1%

Prematurity = 32.0% Distress = 27.3%

death = 1(0.006%)

Breech = l3.9% awareness under general = 1

Multiple Gestation = 8.9% dental injury = 2 amniotic 5uid embolism = 1

Intrauterine Growth Retarded = 5.8% aspiration = 0 These data profile a teaching OB anesthesia service, and contribute to knowledge of

complication rates. Of greater importance to quality management, control charts spanning 72 months indicate a stable service, and are continuously updated. Movement of a data point beyond statistical control limits is a signal to search for “assignable” causes (e.g., training deficiency) and reestablish stability. Statistical analysis of runs of data points indi- cates when a run is unlikely to have occurred randomly. For example, a significant (p < .05) run of low rates of complaints of narcotic-related side effects began when fentanyl infusion replaced morphine in postcesarean epidural pain management.3 Thus, a significant change in clinical practice resets the performance level and control limits of a stable service.

References. 1. Denring WE. OUI of the 0i.ri.x Cambridge, Mass: Massachusetts Institute of Technology, Center for Advanced Engineering Study, 1986. 2. Youngstrom P, er al. Anesfhesiolog+ 69~686, 1988. 3. Youngstrom P, et al. Anesthesiolo~ 73AA908, 1990.

60

_

TITLE: Correlates of ST-segment changes during cesarean section under regional anesthesia

AUTHORS : Zakowski MI, Baratta J, Ramanathan S, Turndorf H AFFILIATION: Dept. Anesthesiology, New York University Med

Ctr, New York WY 10016 INTRODUCTION: Up to 60% of patients have ST segment changes with or without intraoperative events: chest pain, nausea, air embolism and dyspneq,,during cesarean section (CS) under regional anesthesia. We investigated the association between ECG changes and events and hemodynamic alterations. MTRODS: With institutional review board approval, 170 patients for CS were studied. Patients had pre- and post- operative 12 lead ECG. A QMED cardiac holter monitor recorded leads II and V5 continuously from 2 hours pre- to 4 hours post-operatively. Patients received spinal (n=50) or epidural (n=120) anesthesia to a T4 level. Monitoring included blood pressure and precordial doppler. Post-operative CPK-MB fractions were obtained (n=lOO). Chi-squared analysis, logistic regression and t-test were performed at ~~0.05. RESULTS: ST-segment depression occurred 160 times in 44 patients. CPK-MB fraction and ECG were normal in all patients. Air embolism, dyspnea and vasopressor use were not associated with ST-changes. Nausea and chest pain were associated once with ST change. Systolic (SBP), diastolic (DBP) and mean arterial pressure (MAP) change, bradycardia (Pc60) were associated with ST changes <= 3 times, whereas tachycardia 8 times (Fig 1). Sixteen percent of spinal anesthesia patients had ST change compared to 29% of epidural anesthesia patients (~~0.05) with maximum frequency being seen at the time of uterine closure IFia 2). Pulse rate with Sl ?inal anesthesia was lower (p<.O5) than for epidural for most ime periods.

HEMODYNAMICS ASSOCIATED WITH ST CHANGE

CONCLUSION: ST depression

ST CHANGES REOIONAL ANEstHEslA

occurs in 26% of patients undergoing cesarean section and is best correlated with tachycardia. Spinal anesthesia produces a significantly lower pulse rate and incidence of ST depression. ECG changes are not associated with any symptoms, air embolism, persistent ecg change, or elevated CPK-MB. Reference:l) Palmer CM et al: Anesth Analg 70:36-43, 1990. 2) McLintic AJ et al: Anesth Analg 74:51-6, 1992.

61

_

_

-

_-

.-

-

-

Title: EFFICACY OF ORAL NALTRXXONE FOR TREATMENT OF EPIDURAL MORPHIRZ SIDE EFFECTS

Author: a Abboud, MD, J Zhu, MD, W Donovan, MD, A Reyes, RD

Affiliation: Department of Anesthesiology, Los Angeles County+ University of southern California Medical Center, Los Angeles, California 90033

Introduction: Prophylactic oral Naltrexone has been shown to be effective in reducing the incidence of pruritus associated with epidural morphine (1,2). The present study was undertaken to evaluate the efficacy of oral Naltrexone in the treatment of pruritus associated with epidural morphine. Methods: The study was approved by the institutional review board and informed consents were obtained from all patients. Twenty-two healthy patients at term who underwent cesarean section using 2% lidocaine with 1:200000 epinephrine were studied. Patients were given 4 mg of epidural morphine in 8 ml of saline and were randomly assigned to receive orally either 5 mg Naltrexone group I (n=13) or placebo group II (n=9) in 20 ml volume if they experienced pruritus. Pruritus and pain scores were evaluated using the visual Linear Analog scores. Incidence of nausea and vomiting was also noted. If pruritus scores did not drop 50% after two hours after administration of Naltrexone or placebo, 0.1 mg of intravenous naloxone was given and repeated as needed. Data were analyzed for statistical significance using student's t-test or chi-square when appropriate. A P value of co.05 was considered significant. Results are presented in the Graph. 10 patients in group I and 5 patients in group II experienced pruritus. All patients in the Naltrexone group had at least 50% improvement of pruritus scores, mean onset was 78 + 19 min. and the mean duration was 17 + 3 hrs. and none required I.V. Naloxone. Four patients in the placebo group (80%) required I.V. Naloxone. Duration (19 + 5 hours) or quality of analgesia was not affected by the administration of Naltrexone. Discussion: Results from our study indicate that oral Naltrexone is an effective treatment for epidural morphine pruritus with a slow onset but a long duration of action. Further studies are on the way to evaluate the efficacy of I.V. Naloxone followed by oral Naltrexone to treat epidural morphine pruritus.

Pruritus Scores After Oral Naltrexone or Y Placebo : ; ‘Q[

References: 1. Anesthesiology 72:.233-237, 1990. 2. Anesthesiology 65:A200, 1986.

63

._

-

-

-

_

._

__

.._

._

-

TITLE: IN SEARCH OF THE OPTIMAL SPINAL NEEDLE AUTHORS: E. Abouleish. M.D., M. Mitchell, M.D.,

D. Warters, M.D. AFFILIATION: Department of Anesthesiology, University of Texas

Medical School, 6431 Fannin, 5.020, Houston, Texas 77030

The flow rates of 0.9% sodium chloride solution were measured in eleven commercially available types of spinal needles with an infusion pressure of 10 mm Hg at isothermic and steady-state conditions. A new needle was used for each experiment and six experiments were performed with each needle type (a total of 66 experiments). Hagen-Poisseuille Law of Friction for laminar flow was used to calculate the internal diameters of the needles.

The flow rates of needles of the same gauge varied considerably depending on the manufacturer and the thickness of the needle wall (Table 1). Compared to a 26-gauge spinal needle produced by the same manufacturer, the flow rate through the 29-gauge spinal needle was 18% that of the former needle. This explains the difficulty in using the 29-gauge needle and the high incidence of associated failure rate. The 27-gauge Whitacre needle approaches the optimal spinal needle because it has a small outer diameter, a pencil-point, and a rapid flow rate; thus, it is expected to be the least likely to produce spinal headache and can easily identify the subarachnoid space.

64

_

-

_

._

._

_

Bradycardia following Bpidural Blood Patch in PartUrientS

W. E. Ackerman, M.D., P.J.D. AndrewsO, FFARCS, M. Juneja FFARCS, V. Cases-Cristobal M.D., A. Gomez, M.D. B.M. Rigor, M.D. Department of Anesthesiology, University of Louisville School of Medicine, and Norton Hospital, Louisville, KY 40292

Introduction. Neurologic seguelae can occur in ;" pOStpartUm patient following an epidural blood patch (EBP). The purpose of this study was to investigate physiologic changes associated with EBP and to compare them with changes caused by local anesthetics administered in a similar fashion.

Methods. IRB approval and patient informed consent were obtained from 10 ASA I or II patients who requested EBP and from 15 ASA I or II patients who requested epidural anesthesia for cesarean section (CS). Each EBP patient received 15 ml of autologous blood in a sterile fashion through a 17 gauge Tuohy needle. Each patient in the CS group received an equal volume of 2% lidocaine through a 17 gauge Tuohy needle. All patients had needle placement at L2-3 or L4-5 followed by blood or lidocaine while in a sitting position. After needle removal each patient was placed on her left side. Monitoring consisted of automatic blood pressure and respiratory rate monitoring every 2 min x 10 min and every 5 min x 20 min. Each patient's ECG was monitored continually and each patient's pulse and oxygen saturation were monitored continually with a pulse oximeter. EMG and EEG activity were continuously monitored using an Anesthesia and Brain Activity Monitor (Datex, Helsinki, Finland). Statistical analysis was done using the Student's T test and the paired Student's T test where applicable.

Results. There were no differences in demographics between the groups. Ten patients (100%) in the EBP group exhibited a decrease in heart rate (pcO.01) from a mean baseline of 88.6(7.31) bpm to a rate of 51.3(7.6) within 122.6 (16.9) set from the time of EBP which lasted a mean of 12.4 (1.1) sec. No patient in the CS group exhibited bradycardia. No differences were appreciated between the groups with respect to oxygen saturation, blood pressure, EMG or EEG amplitude or respiratory rate.

Discussion. The etiology of transient bradycardia following EBP is unknown. A Cushing response or migration of iron catalysed free radicals from the epidural space might be possible etiologies. We conclude that EBP should be done with intravenous access and ECG monitoring and might be avoided in patients with cardiac disease or increased ICP.

Reference. 1. Bolton VE, Leicht CH, Scanlon TS. Anesthesiolosv 1989;70:146- 149.

* Presenting author.

65

,-

._

-.

._

_

-.

SIMPLE IDENTIFICATION OF LOCAL ANESTHETICS COMMONLY USED IN OBSTETRIC ANRSTBESIA

W.E. Ackerman, M.D., P.J. Andrews. FFARCS, M. Juneja, FFARCS., V. Cases-Cristobal, M.D., A. Gomez, M.D., B. Rigor,M.D.: Department of Anesthesiology, University of Louisville College of Medicine, Louisville, Ky. 40292

Introduction. Local anesthetics mixed with sodium bicarbonate (NaHCO), will result in precipitation'. The purpose of this investigation was to determine if the local anesthetics commonly used in obstetric anesthesia would yield distinctive precipitates when mixed with NaHCOS.

Methods. Following Review Board approval lidocaine, 2%, bupivicaine 0.5% , etidocaine 1% and cholorprocaine 3% were studied. NaHC03 8.4% (3.0 ml) was mixed with 2.0 ml of each local anesthetic in an open test tube. Pentothal has also been shown to form a precipitate when mixed with local anesthetics' , therefore 2 ml of local anesthetic were mixed with 3 ml of pentothal as previously described. Each solution was allowed to stand 10 min at room temperature (23.8 C). At that time each solution was examined for precipitate with 2X magnification. Seven blinded observers were each given 8 unknown test tubes on 2 separate occasions containing the local anesthetic solutions mixed with either pentothal or NaHC03 . Prior to receiving the test tubes, each observer was given a labeled test tube containing a known local anesthetic precipitate. consisted of the X2 test.

Statistical analysis A p value < 0.05 was considered

necessary to reject the Null hypothesis.

Results. Each local anesthetic formed a precipitate with pentothal or NaHC+. With pentothal, the precipitates of the local anesthetics could not be distinguished from one another. With NaHCO, a distinctive precipitate with each local anesthetic was noted: bupivicaine 0.5%, a globular precipitate which immediately settled to the bottom: chloroprocaine 3%, a milky white precipitate suspended throughout the solution: etidocaine l%, a globular precipitate on top of the solution and lidocaine 2%, long thin crystals which settled to the bottom of the solution. No observer was able to distinguish the local anesthetic/ pentothal precipitate but identified the local anesthetic/ NaHC03 precipitate with 100% accuracy (~~0.01).

Discussion. The results of this study demonstrated a distinctive precipitate was formed when local anesthetics were mixed with NaHCOS. This information is most useful in teaching situations or where the contents of a syringe of local anaesthetic are unknown.

References. (1) Reg Anes 13:169-173,198s (2) Reg Anes 14:265-270, 1989

66

-

_-

-

,.-.

-

-~

_

Title: VARIANCE IN THE BARICITY OF BUPIVICAINE .75% IN 8.25% DEXTROSE: IS THIS A HYPERBARIC DRUG? Authors: GH Adkisson MD, JH Waters MD Affiliation: Naval Hospital, San Diego, CA 92134

&ntroduction: Bupivicaine 0.75% in Dextrose 8.25% is considered a hyperbaric drug when used for subarachnoid anesthesia. Previous worki led us to believe that variations in baricity between lots could be significant and that the drug might range from hyperbaric to hypobaric. Alterations in the expected baricity of a drug, either through the addition of other agents or by variance among lots, may alter the final distribution of the drug within the subarachnoid space. This study measured a number of different lots of bupivicaine to determine the variance in densities and therefore the variance in baricities that might be encountered. Methods: Seven lots of bupivicaine, with expiration dates ranging from 4-92 to 4-94, were collected from hospital stock. Each lot was measured (lml) via micropipette and weighed on a scientific balance accurate to four decimals. The density of each solution was then determined and the baricity calculated using a value of 1.003 for the density of cerebrospinal fluid (CSF). Measurements were at 22OC. Results: The density and baricity for each of the seven lots is tabulated below:

Lot# Expiration Density Baricity

II M720HB I 2-94 I 1.0137 I 1.011 II II MOlOHD I 4-94 I 1.0231 I 1.020 II

Two of the lots tested were isobaric and five were hyperbaric. The range was from 1.006 to 1.027 with a mean of 1.015. Discussion: Bupivicaine is standardized during production to a specific gravity of 1.030-1.035 at 25OC using a Pyknometer'. Specific gravity and density are related but baricity, defined as the density of a solution compared to the density of (CSF), is most accurately calculated if the density is measured directly. The differences noted above may account for some of the clinical variation seen with bupivicaine. References: (1) Adkisson GH, Waters JH, Burger GA. Alterations of Subarachnoid Anesthetic Solutions Following the Addition of Fentanyl and Morphine. Anesth Anal 74:Sl 1992. (2) R Gruber. Sterling Labs. Personal Communication

67

__

,-

UPPER FACIAL EMG PROVIDES A CONTINUOUS OBJECTIVE MONITOR OF ANALGESIA DURING LABOR. PJD Andrews FFARCS. WE Ackerman MD, M Juneja FFARCS, HL Edmonds PhD. Department of Anesthesiology, University of louisville School of Medicine, Kentucky, 40209.

INTRODUCTION: Management of epidural analgesia relies upon subjective assessments of the adequacy of pain relief. Recent work' suggests that mean Upper Facial EMG (FEMG) amplitude may provide a useful assessment of adequacy of epidural analgesia in the anxious patient that is superior to heart rate (HR) and blood pressure measurement. The aim of this study was to assess the relationship between FEMG amplitude, uterine contraction (UC) and heart rate during the first stage of labor.

METHODS: Following Ethical Approval and informed consent, 20 ASA I and II term patients in early labor were studied. Monitoring was commenced early in labor when little pain was experienced (verbal analogue score) and continued till severe pain and epidural analgesia commenced.

MONITORING: Intensity of pain was assessed by the patients using a lo-point verbal analogue score (O=no pain, lO=worst pain). HR was recorded using a DATEX OSCAR pulse oximeter and FEMG was derived from surface electrodes placed upon the belly of the medial~ frontalis muscle and a ground electrode on the mastoid process. Biopotentials were rectified, integrated and digitized by an ANESTHESIA and BRAIN ACTIVITY MONITOR (ABM; DATEX). A signal filter was included in the pre-amplifier to improve the signal to noise ratio. The rms amplitude of successive 10 second samples of FEMG as well as heart rate from OSCAR and the output from the external tocotransducer (input to ETCOZ pre-amplifier of ABM: Hewlet Packard) were then graphically displayed and stored in ASCii format to allow assessment of temporal relationships.

RESULTS: The data were assessed using regression analysis, cross spectral array and hypergeometric distribution to examine copulsatility of the peaks in FEMG, HR and UC. Pain score <2/10. No significant relationship was seen between FEMG, HR and UC using the chosen methods of analysis. Pain score >5/10. In every case a significant relationship was seen between FEMG and UC. (P=O, mean R2 32%; range 22 to 41%). Cross spectral array and hypergeometric distribution showed a significant temporal relationship between peaks in FEMG and UC, P<O.OOl (with Bonferroni correction). No significant relationship was seen between HR and UC or HR and FEMG.

CONCLUSION: A continuous display of the relationship between filtered FEMG and UC allows objective assessment of adequacy of analgesia irrespective of patient affect. [l] Upper Facial EMG Quantifies Anxiety and Anaesthetic Adequacy During Labor. A Tabatabai, WE Ackerman, M Juneja et al. ANESTHESIA ANALGESIA in press.

- 68

.-

._

-

-

Title: SERUM LEVELS OF TUMOR NECROSIS FACTOR, INTERLEUKIN-1, INTERLEUKIN-2 AND INTERLEUKIN-6 IN THE PARTURIENT WITH PREECLAMPSIA

Authors: Y Beilin MD, H Bernstein MD, L Mayer MD Affiliation: Dept.% of Anesthesiology end ImmunofogY

The Mount Sinai School of Medicine One Gustave L. Levy Place, Box 1010 New York, NY 10029

Introduction;Tumor necrosis factor (TNF), interleukin-1 (IL-1 1, interleukin-2 (IL-2) and interleukin-6 (IL-6) belong to e class of molecules known as cytokines (0 which are released by activated T lymphocytes and macrocytes during immune reactions. Cytokines may be elevated in disease processes characterized by immune activation but are not detectable in healthy patients.’ Cytokines also play an important role in the regulation of nonimmunologic processes including the regulation of acute phase responses, hemostasis, the production of vasoactive factors and prostaglandin synthesis.

Preeclempsia (P) is a disease unique to the parturient manifested by hypertension, edema and proteinuria whose pathogenesis is unknown. Immunologic rejection of fetal tissue by the mother as well as prostaglandin imbalances have been proposed as possible etiologies of P. Recent studies have isolated C from the amniotic fluid of women during premature labor’ and from the serum of preeclamptic women at term.3 We therefore hypothesized that C with their known immunologic, vasoactive and prostaglandin modulatory effects play a role in the pathogenesis of P.

Methods: After IRB approval, informed consent was obtained from 29 term parturients in labor: 13 were preeclamptic and 16 were healthy. P was defined by the new onset of proteinuria (2 2 + by urine dipstick on two separate occasions) and recent systolic blood pressure increase of 2 30 mmHg or diastolic blood pressure increase of 2 15 mmHg at rest on two separate occasions. Serum specimens were obtained from the women upon admission to the labor floor and again on post partum day one. Serum was also obtained from the umbilical vein at the time of delivery. All blood samples were analyzed by enzyme linked immunosorbent assay (ELISAl for the presence of TNF, IL-l and IL-6, and by a bioassay for IL-2.

Results: The groups were similar with respect to age, gravidity, and parity. Mean blood pressure was 78 mmHg in the control group and 148 mmHg in the preeclamptics. There were no detectable levels of TNF, IL-l, IL-2 or IL-6 in either the control or preeclamptic patients.

Discussion: We have shown that there are no detectable C levels in healthy parturients at term despite the stress of delivery. C are also not elevated in P at term. While it is still possible that C play a role in P they may be elevated earlier in the course of the disease or alternatively are produced and degraded locally in the placenta. Further work is necessary to determine the possible association between C and P.

References: 1. Hospital Prac 25:45-56 1990 2. Am J Obs Gyn 161:336-41 1989 3. Sot Perinat Obs A23 1990

69

_-

-

,_

~_

_

-

THE BELATED CORD GAS - ITS CLINICALUSEEUIi%SS&ic BieberMD, Donna fir2 !4J, Richard Pawlins PhD, Howard Strassner kI9. Push-Presbyterian- St. Luke's Medical Center, Dept. of Obstetrics and Gynecology, 1653 West Congress Parkway, Chicago, Illinois 60612

The current state of the art for initial neonatal assessment includes both neonatal Apgar scores and umbilical cord blood gases. Traditionally, clamping.

cord gases are obtained immediately following cord There may be occasions where the decision to obtain cord

gases is not made until after blood has been drained from the cord for other routine tests. We proposed to evaluate the validity of obtaining cord blood gases following the collection of blood from the cord for routine cord blood tests. Twenty-four patients were evaluated with umbilical cord arterial and venous blood gas samples obtained before and after the cord was allowed to drain for routine cord bloods. Following collection, specimens were quickly analyzed in an adjacent satellite laboratory. pH, pCO2, ~02, HC03 and base excess were determined or derived on the ADL30 (Radiometer : Copenhagen, Denmark) blood gas snalyzer. and pCO2 were statistically similar,

Both arterial and venous pH as were venous base excess, HC03

and total C02. Arterial ~02, HC03, total C02, base excess and oxygen saturation were noted to be statistically different, as were venous pO2 and 02 saturation (p < 0.05). The concept of universal rather than select cord gas analysis has met with limited acceptance in general obstetric practice. Selection of cases for analysis is more frequently practiced, however, it is iqerfect as neonatal status may deteriorate following birth. This study substantiates the reliability of pH and pCO2 measurement on dilical cord gases even when obtained after routine cord blood samples have been collected. In those cases where the decision to obtain cord gases was delayed this assessment of fetal pH and pCO2 may still allow for early neonatal evaluation.

70

_

._-

_.

.-

Title:

Authors:

ABIliation:

Matemal Catecholamixs Decrease During cesarean Section with Subam&tnid Buplvacalx-Oploid Anmtbe& TPBoenxx.M.D.,MCNonis,M.D..HSctdemn,Pl~D..BLLeighton,MD..VAAmoosh, M.D., HJ Hutlhagle, D.O., MTorjnan, M.Bd. Depattment of Anesthesiology, Thomas JeBetson Univetslty, Philadelphia, Rmnsylvania

Introduction: Reducing maternal catecholamines during cesaman section may maintain uterine blood flow and limit possible fetal asphyxia. Catecholamines exhibit plasma half-lives of only 1-3 minutes. Consequently, to track the delivery-related sympathoadmnal response, one must dynami- cally follow maternal norepinephrine [NE] and epinephrine concemrations [El throughout surgery. Systemic fentanyl lessens sympathetic activation intraoperatively.l Therefore. we investigated the changes in maternal [NE] and [E] at set intervals before, during and after cesarean section under bupivacaine-morphine spinal anesthesia with and without subarachnoid femanyl. Methods: Eleven healthy, non-laboring term parturlenta having elective cesarean sections under spinal anesthesia gave informed written consent to participate in this IRB approved smdy. Spinal anesthesia consisted of 12 mg hyperbaric bupivacaine and 0.15 mg morphine. Patients also received 10 pg fentanyl (n=6) or 0.2 mL saline (n=S) imrathecally. To optimize patient cam and minimize catecholamine release. 02 and LUD were employed. AlI patients had a sensory block to T4 or above by the time of skin incision. sBP was maintained above 100 mmHg with iv. fluid and 5-10 mgbolusesofephedrine.Bloodsamplesfor[NE]and[E]dete~inationweredmwnfmmaperipheral vein pre-induction. at 5, 10, 1.5. 30. 60 min. post-induction, and at skin incision, uterine incision, delivery,peritonealclosureandskinclosure.Sampleswerefrozenuntillateranalysisbyhighpressure liquid chromatography with electrochemical detection. Data were analyzed with one-way repeated measures ANOVA; p< 0.05 was considered significant. Results: There were no differences between the saline- or fentanyl- treated groups in demographics or catecholamine concentrations. Pooled data from all patients showed an initial rise followed by a steady decrease in [NE]. [E] dropped immediately and stayed significamly lower than

baseline through the operation. All neonates were vigorous at birth.

vs. 5 min

Norepinephrine 210 1 Epinephrine

0.j I 0 I 10 ,d SWII w PU” sun

ame Clo+ cla ClmI Ti.*(mlm, TIH (Ii.,

Discussion: We found no difference in maternal catecholamine response between the imrathecal femanyl- and saline-treated groups. We did demonstrate a steady decrease in both these endogenous catecholamines during cesarean section under bupivacaine-morphine spinal anesthesia. Two previous studies, using spinal anesthesia with tetracaine alone, found no changes in [E].zJThe mom recent investigation, however, reported a [NE] decrease similar to that in our study.3 Most of the decrease in catecholamines found here may be attributable to segmental sympathetic denervation and adrenal suppression. We have described significant catecholamine reductions with bupivacaine- morphine spinal anesthesia. Additional intramecal fentanyl does not appear to affect this response. References: 1. Anesthesiology 1990;73:5., 2. Am J Obstet Gynecol 1982;142:252., 3. Obstet Gynec011990;75:600.

71

AMBULATORY EPIDURAL ANESTHESIA FOR LABOR

-

._

..-

Authocs: &@$~JJW, Orioi NE

Department of Anesthesia and Critical Care, Beth Israel Hospital, Harvard Medical School, Boston, MA 02215

.~ug&~I; Despite the many advantages of epidural analgesia during labor, one drawback is the inability of patients to ambulate. We hypothesized that by using drug combinations including very low concentrations of bupivacaine, or by using solely epidural narcotics, patients might achieve satisfactory analgesia and retain the ability to ambulate safely.

M&Q& The study was approved by the institutlonal review board. Patients wishing epidural analgesia during labor and consenting to participate in the study were stratified according to parity and cervical dilation:

(1) nuliipamus O-2, 3-5 or 6-10 cm dilated (2) multiparous O-3, 4-6 or 7-10 cm dilated.

Patients were randomized in a double-blind fashion to receive epidural fentanyi (F) or bupivacaine (0.04%), epinephrine (1.7 us/ml) and fentanyl (1.7 us/ml) (BEF). Ail patients received a test dose of 3 ml 1% lidocalne with 1:200,000 epinephrine added, followed by 15 ml of BEF or saline with 75 pg of F added. An infusion was begun at 15 ml/hr containing either BEF or F (2.5 ug/mi). After adequate analgesia was achieved and hemodynamic stablilty ensured, leg strength was assessed (modified Brcmage score) and orthostatlc vital signs were determined. Inadequate analgesia was treated by changing to bupivacaine 0.125% (or higher) plus fentanyl.

Behults: For this report, ail patients who received F were grouped together as were those receiving BEF. Ninety-four patients have been recruited. Six patients are not included in the analysis because of catheter related problems (2 unilateral blocks and 4 catheters that ceased to work). Of these 6 patients, 4 ambulated once, 1 more than once and 1 not at all. Of the remaining 66 pateints, 51 received BEF and 37 F. Demographic information was similar between groups. Nulliparous and multiparous patients were evenly distributed. Of the patients receiving F 64.9% ambulated once, and 24.3% more than once. For BEF, 74.5% of patients ambulated once and 21.6% more than once. Four patients who received BEF never ambulated due to leg weakness. One patient who received BEF and had no discernable leg weakness fell while walking to the bathroom. Seventy percent of patients receiving F, and 36% receiving BEF eventually required bupivacaine 0.125% during the I* stage of labor (p<O.Ol). At delivery, 30% of patients were receiving F and 56% BEF (p<O.O2). There were no differences in the proportions who delivered by spontaneous vaginal delivery, assisted delivery or cesarean section. Patients in both groups were highly satisfied with the analgesia provided, although satisfaction scores were slightly higher for patients receiving BEF !median scores 100 vs 96 on a 1KI mm visual analog scale, p<O.O5).

DiscuwSqn.: Laboring patients with epidural analgesia (F or BEF) can ambulate safely providing they demonstrate lack of orthostatic hypotension and adequate leg strength before walking. Patients should always be assisted while walking as emphasized by one patient who fell while ambulating. Breakthrough pain during the 1” stage of labor can be satisfactorily managed with increased concentrations of bupivacaine.

72

_

-.

Title: Splnal Morphine and Fentanyl for Labor: A Technique In Need of Reflnement

Authors: wCaldwell. SM Shnider. MD, M Rosen, MD, C Fong. MD Affiliation: Depanment of Anesthesia, University of California, San Francisco, CA 94143

Purpose: The combined spinal-epfdural (CSE) technique for labor analgesia has been described (1.2). The purpose of this study was to compare the incidence of side effects associated with the CSE technique relative to that assodated with epidural analgesia. Methods: We retrospectively studied 66 healthy partunents admitted to our institution for delivery between 7/l/91-6/31/91. Twenty-six of these patients received intrathecal morphine sulfate 0.25 mg, and fentanyl, 25 pg (MS 0.25/F 25), and 7 patients received mofphine sulfate, 0.125 mg and fentanyl. 25 ug (MS 0.125/F 25). The control group was comprised of 33 consemtive patients who received a continuous epidural infusion of a dilute concentration of bupivacaine. 0.0625% or 0.125% and sufentanil, 0.1 or 0.2 ugml. In both groups, an l&gauge Tuohy needle was placed in the L2-3 or L3-4 interspace with loss of resistance technique. In each of the CSE patients, a 24-gauge x 120 mm Sprotte spinal needle was then placed through the epidural needle for intrathecal injection of morphine and fentanyl. The spinal needle was then removed, and a lumbar epidural catheter was placed. Twenty-seven of 33 patients requested additional analgesia, which was administered epidurally. After delivery, patient charts were reviewed for the incidence and treatment of intrapartum nausea/vomiting, pruritus, respiratory depression, and spinal headache. The duration of intrathecal analgesia was defined as the time from intrathecal injection to the time of epidural drug administration (mean f SD). Unpaired t-tests and Chi-square analysis were used to evaluate demographic data. Chi-square analysis also was used to evaluate the incidence of side effects and therapy A value of ~~0.05 was considered statistically significant. Results: The two groups did not differ in age, weight, panty, gestational age, mode of delivery, or duration of the first or second stage. Over the course of labor the control patients received an average of 27k16 frg of sufentanil. The duration of intrathecal analgesia did not differ between the groups given MS 0.25/F 25 and MS 0.125/F 25 (232 f 220 tin vs. 291 k 263 min respectively). The incidence of side effects and requirement for therapy differed sign\ficantly between CSE and control (epidural) group patients. No patient developed significant respiratory depression. Only one patient developed a postdural puncture headache (PDPH). after a “wet tap” with the 18-gauge Tuohy needle during CSE; no PDPH occurred with the use of the Sprotte needle. The incidence of side effects was similar in the two CSE groups: therefore, we combined them for statistical purposes for comparfson with the epidural group (Table). Forty-eight percent of the patients in the two groups experienced nausea/vomiting and 48% developed pruntus, compared with 15% and 3% (p= 0.008, p= O.OOOl), respectively, in the epidural group. Thirty percent of the CSE patients required therapy for nausea/vomiting and prurftus. compared with 0% and 3% in the epidural group (p=O.O02. p-0.008).

TlLd 50% nx II z

15% 0% I

quire

consistent with reports from prior studies(3): References: 1. E Abouleish. et al: Anesthesiology 74:711-716.1991

2. EL Leighton, et al: Anesth Analg 69:122-125.1989 3. M Cesanni, et al: Anaesthesia 45:656-658,199O

.-

-

-

Title: THROMECELASTDGFIAPH~C STUDIES IN THE PARTURIE~V~

Authors: -bell. LCampbell, W.T.

Affiliation: Department of Anesthesia, Indiana University School of

Medicine, Indianapolis. IN. -

Introduction. Thromboelastography (TEG) is a convenient and easily performed method of evaluating overall clot formation in the operating room. Pregnancy is known to produce alterations in coagulation function. Therefore, TEG may be useful in the obstetric suite. There are no published data describing normal TEG parameters in the parturient. The purpose of this study was to gather TEG data to determine: a) what constitutes “normal” TEG parameters in the parturient, b) observe what effects, if any, epidural analgesia produces on coagulation function when used to control labor pain, c) document any differences in coagulation when delivery is by the abdominal route, contrasting TEG parameters in patients receiving general anesthesia with those receiving a regional anesthetic, and d) demonstrate that TEG is a rapid, reliable and convenient montor of coagulation in the obstetric suite. Methods. After Institutional Review Board approval and informed patient consent from all subjects, TEG data was obtained in two groups of patients: Group I

consisted of patients in active labor and anticipating a vaginal delivery. Blood samples were drawn on admission and then again 60 mins. after the institution of epidural analgesia. Group II were patients undergoing cesarean section. Samples in this group were obtained preoperatively (immediately prior to induction), intraqperatively (during closure of the abdominal wall), and on the first post- operative day. All samples of blood were examined for coagulation function in their ‘native state’ using a commercially available TEG machine (Thromboelasto- graph, Hemoscope Corp., Glenview, IL). The data so obtained was then subjected to statistical analysis.

. ResultsThe protocol outlined above represents work in progress. At meeting time we will be prepared to report the results in our completed study population. The presented data will be used to make the following comparisons: 1) TEG in the pregnant vs. the non-pregnant condition, 2) TEG parameters in active labor, before and after the initiation of epidural analgesia, 3) TEG parameters in cesarean vs. vaginal delivery patients, and 4) TEG parameters in patients receiving general vs. spinal or epidural anesthesia for cesarean section.

1. Anesth. Analg. 66: 856-63, 1987. 2. Anesth. Analg 73: 696-704, 1991.

_

-

.-

Title: A Survey on the Availability of Obstetrical Anesthesia in the State of Indiana

Authors: I;amDbell C,Erhlinger,S. Affiliation: Department of Anesthesia, Indiana University School of

Medicine, Indianapolis, IN. duction, A national collaborative survey of anesthesiologists

and obstetricians was conducted by Gibbs et al in 1986 to define the practice of obstetric anesthesia and determine why anesthesiologists are not more involved in its’ practice. Our study was performed to compare the current availability of obstetrical anesthesia coverage in the State of Indiana to the national trends indicated by Gibbs’ study and to determine if there had been any improvement in the problems previously identified. MethodS, A questionnaire was devised to obtain statistical data on personnel and methods, and also to identify problems related to securing anesthesia availability. Two copies of the questionnaire were then sent to each hospital in Indiana reporting births, one copy to be completed by the chief of obstetrics and the other by the chief of anesthesiology. Results and discussion, We found that the availability of obstetric anesthesia in Indiana remains low. Full-time anesthesia personnel were available in only 14% of the responding hospitals during week- days, and in 11% of the hospitals during nights and weekends. The hospitals with ~500 births were the most underserved. When general anesthesia was used for cesarean section in these units, it was provided by an anesthesiologist only 50% of the time. Likewise, in the small units, personnel classified as “others” were responsible for newborn resuscitation in 38% and 28% of cases after cesarean section and vaginal delivery, respectively. The reasons why anesthesia personnel are not more involved on obstetric anesthesia appeared to be mirror those found in the national study- the unpredictability of labor makes scheduling difficult, obstetricians tend to dictate the type and timing of anesthesia, the risk of malpractice claims is higher, and larger obstetric services would make it more practical to provide anesthesia services. In summary, little progress is appears to have been made in improving obstetrical anesthesia availability in Indiana. Attitudes are stagnated with little indication of the possibility of change in the near future. References. Anesthesiology 65: 298-306, 1986.

75

AORTOCAVAL COMPRESSION AND SAFE POSITIONING.

.-

._

.-

_.

Dr S. M. Kinsella, Department of Anaesthetics, Hammersmith Hospital, Du Cane Road, London W12 ONN, England.

The dangers of the supine position in late pregnancy are now familiar to obstetric

anesthesiologists but lack of knowledge among other health care workers may have

led to inappropriate treatment. When supine hypotensive syndrome was not identified

and the maternal position modified accordingly, there was a poor response to anti-

shock therapy and one woman died among four so treated’.

A recent report of maternal and fetal fatalities after emergency transfer in the supine

position suggests the use of pelvic or lateral tilt for management and transportation of

critically ill pregnant worned. However, the complete relief of aortocaval compression

is not guaranteed with a standard 15” tilt. Cardiac output increased when left uterine

displacement was applied in addition to 15” til?. Aortic compression may bc present

with 34” of tilt’, and decreased leg blood flow, indicating inferior vena caval

compression, is found even in the semi-lateral position’.

Medical, nursing and para-medical staff should be encouraged to use the left lateral

rather than “supine-with-tilt” position wherever possible for maternal management

including labour, operation, intensive therapy and emergency transportation.

1. Erofeev IuN, Kiseleva KS. The significance of the syndrome of compression of the

inferior vena cava at the last stage of pregnancy. Akus I Gynec (Moskva) 1969;9:72-4.

2. Katz VL, Hansen AR. Complications in the emergency transport of pregnant

women. South Med J 1990:83,7-10.

3. Secher NJ, Amsbo P, Heslet Andersen L, Thomsen A. Measurements of cardiac

stroke volume in various body positions in pregnancy and during Caesarean section:

a comparison between thermodilution and impedance cardiography. Stand J Clin Lab

Invest 1979;39:569-576.

4. Kinsella SM. Whitwam JG, Spencer JAD. Aortic compression by the uterus:

identification with the Finapres digital arterial pressure intrument. Brit J Obstet

Gynaecol 1990;97:700-705.

5. Drummond GB, Scott SEM, Lees MM, Scott DB. Effects of posture on limb blood

flow in late pregnancy. Brit Med J 1974;2:587-588.

76

lltb THE EFFECT OF EPINEPHNINE ON THE lNClDENC5 OF FEML HEART NATE DECE,.ERAT,ON5 FC,J.OW,NO 5UPI”ACAINE WDURAL ANESTHE9fA

Amho”: bnon. DD. 9Uwrton. JC

Affiliation: D*putm9m of Annthuia. Women’s Hoepital. MwnotfaI Msdkal Cent”. Long 9a&t, CA

!g&&&& Tha purpow of this study was to datetins it the inoidsncs of fatd heart rate deoslsmtions following bupivacdne epidunll anesthesia could be reduced by ths addition of spinsphrirta 1:400.ooO to the looa anesthetic. The incidence of fetal hart rate deeslsrations following bupivmcaine spidural is reported to be between 7.9% and 19% ,“roman. Abboud,.

&@&. Ths protoed was approve,, by the de,,.rtmsnt of resesrch administration. 205 conaeoutive IMoring patients ware stud&d. Those patients with pregnancy induced hvpartwwion, preeclampsia. fetd distnes or a contraindication to recdw epinaphrinm were sxoluded. Whan patients requested spidurd anesthesia. they were randomized to receiw dthar l2ec 0.25% bupiivacine (control group) or 12 co 0.25% bupivacaina with t:4OO.o00 epinaphrins (JOmop epinaphdne grwp). 5-h patient wn pr+-drated with 1400~~ Iactamd Ringers solution in the 30 minutes preceding injection of the local anesthetic. The spidural space was located at the I.34 Ie”eI with an 18 gauge needle while the patient was sitting. Freotional doses were used. After inisction. ths patients were placed in Ieft uterine displscement and blood pressures were measured at 5 minute intervals for 30 minutes. FHR tracing and utsfins contraction* were monitored continuously.

&&g. The two groups were similar with regard to maternal oharaotetisti~s. Fetal deceleration was considered to be a drop of the fatd heart rate below 120 beats per minute for two minutes within 30 minutes of the completion of the loading doss. Utsrins hypsnonus was defined as abnormal elevation of basal uterine tones between oonttactions. or an increase in the number of oontractions per 10 minute inte~als. Maternal hwotsnsion was dsfineo as a drop of greater than 20% from baseline maternal blood praesuras.

Fetal Uterine Matarm, Decelsration Hwanon”s H* \otansion

Control 196 13136 13.5% 8,98 8.3% E/96 6.25%

Epi”*ph,i”a x109 7,109 6.4% a109 5.5% 111109 10.1%

p = 0.14 p = 0.50 p = 0.45

Results were analyzed by the Chi square test with Yates correction and statistical significance wav not shown at the 0.05 loveI. A sampIo size of 307 would provide 90% power to detect the difference in incidence of fstal hewt rate decelerations noted.

Discussion. Bupivacains may cause “asoconstriction of uterine and ~Iacmtal vessels and is associated with “twine hypertonus in patients with fetal heart rote decelerations following bupivacaine spidural anesthesia. The addition of spinaphrine to the looa anesthetic solution may decrease uptake of bupivacains in the uterine “nsculatwe or relax uterine tons through a sympathetic effect. It would be useful to determine the background Ie”eI of fetal dsoslsratians. We hope to continue this study in attempts to achieve statistic.4 significance. Addition of t:400.000 spinsphtina to bupi”aoaine spidural anesthesia may decrease the incidence of fetal heart rate dsoslsration. especially in patients with uterine hvpertonicity.

RdW~“CO.

1. Stsigsr RM. Nagsotts MP: Effect of uterine contractility and maternal hwotsnsion on prolonged dscslsrstiona after bupivacains epidurai anesthesia. Am J Obstst G”necoI: 163: 808-I 2. 1990.

_

77

-

-

-.

_

-

Title: PARIATIOR IB EPIDURAL SPACE PRBSSURE DURING PRRGRRNCY

Authors: ?$ &j& m, TK Abboud, M, K Boo BOO, MD, J Zhu, MD, M Richardson, MD, K Peres Da Silva, KD, II Donovan, MD

Affiliation: Department of Anesthesiology, Los Angeles County+ University of Southern California Mediaal Center, Los Angeles, California

Introduction: A precise determination of the epidural space is essential in the application of epidural block analgesia or anesthesia. This can be difficult at times using the loss of resistance technique. The present study was undertaken to evaluate a device (Episensor) which is fitted with a high resolution electronic vacuum sensor which detects the negative pressure up to 1.5mm H20 using luminous and acoustic signals.

Method & Materials: Forty-two patients requiring epidural analgesia during labor were .studied after Institutional Board approval and informed consents. Patients were placed in the lateral position and the spines were fully flexed. An 18G Tuohy needle was slowly inserted at Ll-L2 level with the stylet in place until within approximate reach of the ligament flavum. The stylet was then removed from the epidural needle and the sterile pressure sensing tubing was connected to the epidural needle with the luer-lock connectors airtight. The Episensor unit was then switched on. The needle was advanced until the acoustic signal and light source came on indicating that the tip of the needle had reached the epidural space. The tube was then disconnected from the needle. Epidural catheters were inserted in all patients and epidural analgesia was established in the usual manner. Advancement of the needle was done between contractions.

Results: The acoustic signal and the light source of the Episensor came on in 12 patients (29%). In 30 patients (71%) the needle was felt to be in the epidural space but no signals were detected, and verification of the correct position of the needle was done using the loss of resistance technique.

Discussion: Results from our study indicate that negative pressure is not always present in pregnant women during labor even in between contractions. These findings are consistent with those previously reported by Usubiaga et al. (1) who found that negative pressures are not observed in pregnant women at term. Identification of the epidural space using loss of resistance technique in pregnant women at term is a more reliable method than techniques utilizing negative pressure.

References: (1) Usubiaga EJ, Wikinski JA, Usubiaga LB: Epidural pressure and its relation to spread of anesthetic solutions in epidural space. Anesthesia and Analgesia 64:440-446, 1967.

-la

-

Tile: EPIDURALANALGESIA IN PATIENTS WITH INTRAUTERINE FETAL DEATH Authors: Andrsw Maslow, Terrance Breen; Nancy Oriol Affiliation: Department of Anesthesia: Seth Israel Hospital: Harvard University. Boston, Mass,

Introduction: Intrauterine fetal death (IUFD) occurs in approximately 89/1ooO pregnanciess.

IUFD complicates tin pregnancies 0.5 to 6.8Y 0s. Labor and delivery are usually uneventful. Zero

to tan percent of these cases display hypofibrinogenemia (< 200 mg/dl) at diagnosisl,e,d, After

five weeks, this may increase to 255O%t~,4. The potential for clotting abnormalities may increase

the risk of epidural anesthesia for labor.

Methods: We reviewed patlent charts in which the diagnosis of IUFD was given from 19&l- 1991. Our data included age. parity, gestational age at delivery (GAD). number of days of retained dead fetus (dIUFD). mode of delivery, year of dellvery. pregnancy related diagnosis, type of anesthesia, and coagulation studiss. Normal coagulation studies were normal platelets (~15O,ooo/ml) +/-normal PT and PTT (based on laboratory control). fibrinogen (>200 mgfdl). and fibrin spin products (FSP; ~40 r&!/ml). Subnormal was defined as having one abnormal value while the others wsre normal. Abnormal studies meant prolonged PT and PlT, low fibrinogen, elevated FSP. and low platelets consistent with disseminated intravascular coagulation (DIG).

Results; 152 charts were reviewed. The mean and median values for age of patient was 30 years. The mean dlUFD was 3.7 days and the median was 1 day. The mean and median GAD was 30 weeks. There was a bimodal distribution of GAD with clusters around 27 and 38 weeks. There were five patients with dlUFD >18. two of which had subnormal coagulation studies (1 low fibrinogen: 1 low platelets). There were 18 subnormal clotting studies (5 low platelets; 2 low fibrinogen; 2 elevated FSP; 6 prolonged PIT). There was a statistically significant relation between pregnancy related complications (e.g. abruptio placentae. placenta previa, PIH) and clotting abnormalities (P<.oOl). Fifty three percent (9) of the patients with abruptio placentae (17) had subnormal or abnormal studies. There were 7 cases of DIC. Six of these had a diagnosis of abruption and the seventh had both uterine and bowel perforation. of the patients with PIH and/or HTN (12) only 2 had subnormal studies and none had DIC. There were a total of 23 patients with subnormal or abnormal clotting studies which is 15% of the study group.

There wars 14 US: 11 of which were performed under general anesthesia, 1 with spinal anesthesia, and 2 with epidural anesthesia.

There were 11 twin pregnancies with one or both fetuses dead. These patients were more likely to have longer dlUFD (p<.CO5). and deliver by C/S (p-X01). Nine percent of the twin pregnancies had subnormal cloning studies compared to 16% of the single gestation population

(p-NSL There was M significant difference in patient population from 1964-1991 with respect to age,

panty, GAD, (IIUFD. and C/S rate. From 1984-1990 9.8% of IUFD patients had epidural analgesia, while in 1991 45O/0 had epidural analgesia for labor (p405). Overall there were 3 patients with low platelets (all > 100,ooO pits/ml) who received epidural anesthesia. Otherwise patients with sub- or abnormal clotting studies did not receive epidural anesthesia. Additionally patients older than

30 years (p+X) or those delivering at GAD > 30 weeks fp<.Oi) were more likely to receive epidural anesthesia. One epidural catheter was replaced because of suspected dislodgement after 24 hours of labor. Otherwise there were no repotted complications of epidural anesthesia,

Conclusions: The incidence of DIC was 4.6% and occurred only in cases of abruption or of a perforated uterus and bowel. There was a 15% incidence of clotting abnormalities (subnormal and abnormal). The use of epidural anesthesia increased in 1991 without any change in C/S rate. In the context of IUFD with normal cloning studies epidural anesthesia is safe. Serial studies may be warranted when abruption is suspected.

References: 1. LL Phillips PhD et al, Am. J. Obst. and Gynec.. Vol. 89 No. 7. Aug. 1. 1964. p 903, 2. J.A. Enborn, Am. J. Obstet. Gynecol. Vol. 152, 1985. p. 424 3. J.A. Pritchard, M.D., Obst and Gynec., Vol 14. No. 5, Nov. 1959, p 573. 4. Hemostasis and Thrombosis 2ed. JB Uppincon Co., Ch 58, 1987. 5. SE. Finley, M.D., Medical Clinics of N.A.. Vol. 73, No. 3. May 1989. p 723.

79

.-

Title:

Authors: Affiliation:

Pat-Dural PunctureHeadacheinObstetrics: AComparison Between 24g Sprotte, 259 Whitacre, and 26g Quincke Spinal Needleo wm, Isner RJ, Palmer CM, Voulgaropouloa, DS Oopartment of Anesthesiology, University of Arizona, TUCSON, AZ, 85724

introduction: While literature suggests the Sprotte needle has a low incidence of poatdural puncture headache (PDPH) in the obstetric papulation,ly its cost is considerably higher than most spinal needles. We compared the incidence of PDPH and ease of use of 249 Sprotte, 259 Whitacre, and 269 Quincke needles in obstetric patients.

U&hod8 i Following approval by the IRS, 102 ASA Class I and II women presenting for non-urgent cesarean section gave verbal consent and enrolled in this randomized, double-blind mtudy. Patients with a history of chronic headaches and those requiring more than one dural puncture were excluded. The three different spinal needles were randomly assigned. Following rapid IV hydration with 1.5-2-O 1 crystalloid, placement was performed with the patient in the sitting position using a midline approach through a 2Og If" introducer. When using the Quincke needle, the bevel was oriented parallel to the dural fibers. Patients received either 12-15mg 0.75% hyperbaric bupivacaine or SO-100mg 5% hyperbaric lidocaine, and 0.2-0.&g preservative-free morphine sulfate inttathecally for post-op pain. After placement, the anesthetist rated ea8e of needle use (1 being easy to 3 difficult), noted number of paeses required, and cold-spray level achieved. Patients were followed for three days postoperatively by an investigator blinded to the needle used. Headaches were rated by severity (l-mild, I-moderate, 3-incapacitating), postural nature, and treatment required. Demographics, ease of use. and number of passes were analyzed using ANOVA. Headache incidence was analyzed using the Kruskall- Wallis l-way ANOVA.

&lsulta: Forty-three patients were randomized to the Sprotte group, 28 to the Whitacre, and 31 to the Quincke (p=n.s.). There was a small but statistically significant difference in age between the Sprotte group (26.7 yre, SE&l=0.875) and the Quincke group (29.5 yre, SEH=l.OO) (~~0.05). The ease of use, number of needle passes required, and cold-spray level achieved showed no significant difference between the groups. One patient from each group had a mild non-postural headache which required no treatment. The incidence of postural headaches was O/43 or 0% for the Sprotte group, 4/2S or 14% for the Whitacre group, and O/31 or 0% for the Quincke group (p~O.05). All postural headaches responded to fluid encouragement and NSAIDS, and none required epidural blood patch.

Discussion: Well-controlled studies comparing the Sprotte to the smaller gauge Whitacre and Quincke needles have been limited. The low incidence of PDPH attributed to the Sprotte spinal needle commends it for use in the obstetric population, but the relatively high cost of the Sprotte needle (approximately $10) compared to other widely used needles (< $2.00) may limit its availability for home centers. Like the Sprotte, the Whitacre needle has a non-cutting tip, and might have been expected to have a PDPH rate similar to the Sprotte; while this ongoing study has not found any difference in ease of use of the 3 needles, it does indicate a higher incidence of mild PDPH in the '25g Whitacre group.

References:

1. REGIONAL-ANAESTHESIE 1987; 10:104-108. 2. ANAFSTHESIA 1990; 45:656-658. 3. REGIONAL-ANAESTWSIE 1990; 13(5):124-128.

-

-.

-

-

,.,_

-

-

_

._.

Tide: The effect of iv eryduomycin on gasttic volumes in postpartum patients undergoing tubal s-n

Authors: -CH. Wilhitc. A, Bartolo G. Shah J, Blass NH

Aftiliation: Department of Anesthesiology. Medical College of Virginia, MCV Station, Box 695, Richmond. VA 23298

m Pregnancy cattses aaatomical and physiologicat changes ia the mated gastrointestinal system that delays gastric emprying aad increases gastric v0lmne.s. The gastrointestinal changes persist into the early postpanum period and increase dx risk of matemal pulmonary aspiration of gastric coatcots when anesthesia and surgery is performed during this period. Erydtromycin. a macrolide antibiotic, possesses

motilin agonist properties and has been shown to hasten gastric motility.1 The purpose of this

investigation was to determine the effect of a 1 time pm-operative 2Khttg dose of erythmmycin on gastric

volumes in patients undergoing GA for postpartum tubal stcrilizidon. &&Q&Z After obtaining approval from the university’s human subjects committee, 33 ASA class I or II partmienu requesting GA for tubal sterilization were randomly assigned to receive eidter: 200mg of erydtmmycin, or 50ml saline placebo. The erytbmmycin and saline placebo were adminiswed iv, 1 hour prior to surgery and all patients were routinely npo prior to surgery (including medications and antacids). Following induction of anesthesia and tracheal intubation a #18 salem sump tube was inserted and the stomach was emptied. Tube placement was confmcd by auscultation of injected air and the positive return of gastric contents. Three separate tube insertions and aspirations were performed. The gastric contents was assessed for volume and pH under “observer blind” conditions. Data was analyzed using the I test for independent samples and a p < .05 was considered significant. &&& The eryduomycia group had a significantly lower gastric volume and higher pH compared to the control group. (Table) The groups did not differ in age, ht, weight or hrs from delivery but, did differ with regard to hrs npo (Table). Dlscusslon: This study confums that (1) stomach emptying remains delayed and gastric volumes are increased in the early postpartum period and (2) erythmmycin 200 mg iv hastens gastric emptying and significantly lowers gastric volume (below 25mI) and raises pH (above 2.5) when given to patients in the early postpartum period. The high gasaic fluid pH found in the erythmmycin group may refkct bile reflux in the presence of complete or near complete stomach emptying. The results of this study suggest that eryduomycin may be useful ia preventing pulmonary aspiration in obstetric patients.

erythromycin (n = 15) m+sd

gastric volume 9.1 + 5.89 gastric pH 4.512 2.11 bapo 14.6 + 2.1 age (yrs) 26.7 + 4.0 ht (in) 63.8 + 4.4 weight (lb) 156.0 + 30.0 hrs post delivery 31.1 + 13.4

(n=l7) m+sd

35.5 + 21.0 2.71 + 2.17 17.88 + 5.44 25.9 + 4.0 63.9 + 2.3

163.0 + 40.3 35.6 f. 15.6

P

.ooOl’

.02*

.03*

.61

.91

.56

.29

Referelces l.Peetcrs T, Matthijs G. Depoortcre I, Cachet T, et al. (1989) Erythromycin is a motilin receptor agonist. -Journal W_, G470-G473

81

_

_.

_

_

Iilk The incidence of posidural puncture headache in morbidly obese parturients.

Authors: Roshen Moreno DO, Eveline Fame MD, Ronald A Thisted, PhD Department of Anesthesia and Critical Care, The University of Chicago, Chicago, IL 60637

-The incidence of dural puncture during attempted epidural anesthesia in morbidly

obese parturients is =4%.1 When dural puncture occurs one option is to convert the anesthetic to a continuous spinal. The incidence of post dural puncture headache (PDPHA) in parturients who have a dural puncture with a 17 or 18 gauge epidural needle varies from 24-75%.* In this study, we compared the incidence of PDPHA after either continuous spinal anesthesia or continuous epidural anesthesia following unintended dural puncture in morbidly obese and not morbidly obese parturients. Methods: During the period January 1, 1988 - December 31, 1991, when a dural puncture occurred during attempted epidural analgesia in a parturient, the anesthesiologist chose one of two options: 1: to pass a 20-gauge catheter through the needle into the subarachnoid space for use as continuous spinal anesthesia or 2: to withdraw the needle and place an epidural catheter in an adjacent interspace. The parturients who suffered a dural puncture were followed daily, and notes were made concerning symptoms and treatment. When the diagnosis of PDPHA was made, patients were treated conservatively with increased oral and/or intravenous fluids, abdominal binder and oral pain medications for 24 hours. If the patient showed no improvement, an epidural blood patch was offered. Medical records from these patients were reviewed and details of hospitalization and postpartum clinics were recorded. A total of 140 medical records were reviewed and data from loo patients were eligible for the study. Parturients were divided into four groups based on Body Mass Index [(BMI) = Weight(Kg)/height(m)2] and type of anesthesia they received after dural puncture (Table). Chi-square analysis was used to compare type of anesthesia in the four groups. Logistic regression was used to calculate the relative risk of headache and of headache requiring blood patch among the groups of parturients. All P-values are based on two-tailed tests, PcO.05 was considered significant. B!z&z Table The incidence of PDPHA and bloodpatch in all four groups:

_GUluo Ane&esia N n I/o) 0 n f /Q) 1. Morbidly Obese, BMl>30 Spinal 19 4 (21) 01 4 2. Morbidly Obese, BMl>30

(i) Epidural 14 4 (28) 31 4

3. Nonobese, BMlc30 Spinal (21)

21 7 (33) 41 7 4. Nonobese. BMlc30

(19) Epidural 46 23 (50) 7/23 (15)

Continuous spinal anesthesia was used more often in the morbidly obese parturients(Pc0.05). in morbidly obese parturients who received continuous spinal anesthesia, the relative risk of having a PDPHA was 0.4 times that of the other three groups (PcO.05). The incidence of PDPHA requiring blood patch in group 1 patients was 0% (0 of 19 women) compared to 17% in the other three groups (PcO.05). None of the four patients in group 1 with a PDPHA required a blood patch, compared to 14 of the 34 (41%) patients with PDPHA in the other three groups (P =o.o5).

‘. DJscusslon. We found that morbidly obese parturients who receive continuous spinal anesthesia after dural puncture with an epidural needle have a decreased incidence of PDPHA and a low incidence of severe headaches necessitating an epidural blood patch. References: 1. Hood DD, Dewan DM, Kashtan K: Anesthesia outcome in the morbidly obese parturient. Anesthesiology 73: A952.1990. 2. Norris M C, Leighton BL: Continuous spinal anesthesia after unintentional dural puncture in parturients. Regional Anesthesia 15: 285-287. 1990.

82

-

,.,-.

_-

._

-

Title: Low back pain following epidural block for post parturn tubal ligation using 3% 2 chloroprocaine with rodlum EDTA, 3% 2 chloroprocalne with metablsultite or 2% lldocalne.

Authors: HA Muir M.D., JL Buxbsum M.D., LB Profets M.D., TG Cheek M.D., BB Gutsche M.D.

Atflllatlon: Departments of Anesthesia, University of Pennsylvania, Philadelphia, and Grace Maternity Hospital, Dalhousie University, Halifax, N. S.

Introduction: Epldural injection of 2 chloroprocaine (2CP) containing sodium EDTA as an antioxidant has been associated with back pain and paraspinous muscle spasm.’ To ascertain whather this effect Is associated with the sodium EDTA or chloroprocaine itself we are determining the presence or absence of beck pain In patients undergoing tubal ligation within 49 hours of delivery with epidural anesthesia using one of two formulations of 2CP or 2% lldocaine.

Metha: Informed consent was obtained from all subjects for this investigation approved by our University Human Studies Committee. Patients with a history of back pain prior to delivery or who required three or more attempts at epidural placement were excluded. Using a randomized double-blind technique 29 patients were assigned into 3 groups; subjects in group A received 3% 2CP with EDTA (0.111 mg/ml, Astra Pharmaceutical Products, Inc.), group B, 3% 2CP with metablsulflte (1.8 mglml, Abbott Laboratories) and group C, 2% lidocaine (Astra). After local Infiltration with 1.5% lidocaine with 1;200,000 eplnephrine, the epldural space was entered with an 18g Tuohy needle with an additional 3 ml Injected through the needle. A closed end multipart catheter was placed. The study drug was injected in 5 ml Increments in sufficient emount to achieve a T4 loss of cold sensation (meanaz26t4ml). Addltional study drug was injected as required to maintain or reinforce the block (Total mean doser39i7ml). All patients were evaluated for the presence of back pain, tenderness end pera!plnous muscle spasm at the time of complete block regression and before additional analgesics were given. Thus far twenty nine patients have been enrolled in this ongoing study. Eight patients were eliminated because of inadequate block, or technically difficult surgery requiring block supplementation with an excess of 100 pg fentanyl and/or 5 mg midaxolam.

Reeulte: One patient receiving 2CP EDTA had back pain associated with muscle spasm that lasted 3 hours, another rsceiving 2% lidocaine had back pain associated with muscle spasm that lasted less than 1 hour. Both subjects reported pain as the block regressed. No patient receiving 2CP metabisulflte experienced back pain or spasm. Presently there is not sufficient data to determine if there is a difference between groups. We expect to recruit 90 subjects in the study.

Comment: Although the number of subjects studied to date is small, neither 2 chloroprocaine nor the type of preservative it contains appears to be associated with back pain or spasm compared to lidocaine 2% in the post partum patient undergoing tubal ligation.

’ Fibuch E et al: An&h Analg 1989; 69: 113-125. Hynson J. et al: Anesth Analg 1991: 72: 25% 256, Levy L et al: Anesthesiology 1989: 71: 476

a3

-

_

Title: Labor analgesia with intrathecal fentanyl using a combined spinal - epiduraI technique

Authors: Muir H, MD*, Hanlon T, MD, Cheek TG, MD, Gutsche BB, MD Affiliation: Department of Anesthesia, Hospital of the University of Pennsylvania, 3400

Spruce St, Philadelphia PA 19104

Introduction: IntrathecaI fentanyl provides excellent analgesia with a rapid onset for the first stage of labor without the high incidence of troublesome side effects associated with inttathecal morphine and the need for prolonged respiratory monitoring.l.2. A recently developed needle (Sprotte 24g) may reduce the incidence of post-lumbar puncture headache. Our purpose was to examine the combined technique of intmthecal fentanyl for first stage labor analgesia with simultaneous placement of an epidural catheter3 for use as labor progresses and observe duration of analgesia, degree of pain relief and side effects or complications. Methods: Following institutional IRB approval, 30 ASA 1 or 2 patients in active labor who requested regional analgesia and gave informed consent were studied prospectively. After a MO ml fluid load and using sterile technique, the epidural space was identified with an 18g epidural needle using loss of resistance technique. A 24g 120mm Sprotte needle was, advanced through the epiduraI needle until CSF flowed freely. Fentany137.5 mcgs (0.75 ml) man equal volume of normal saline was injected and the spinal needle withdrawn. A 20g epiduml catheter was then passed into the epidural space and secured. Analgesia and pruritus were measured using visual analog pain and itch scores (VAPS and VAIS) immediately prior to fentanyl injection and at 1.2, 5, 15,30,60,90, 120 minutes after injection. Epiduml analgesia was provided with local anesthetic or narcotic when the patients requested additional pain relief.

A retrospective analysis was done on 260 patients who received intrathecal fentanyl using the double needle technique for analgesia in labor noting the complications of hypotension (defined as a fall in systolic blood pressure of greater than 20% below baseline or to less than 100 systolic),epidural malfunction (defined as no block,inadequate block or unilateral block), post dmaI puncture headache (PDPH-defined as a headache with a definite postural component and/or improvement with abdominal pressure/binder),and inadvertsnt placement of an intrathecal catheter.This data was compared to that obtained from a cohort of 260 patients who received traditional epidural analgesia for labor using either 0.25% Bupivacaine or 1.5% lidocaine. Results: Mean duration of analgesia in the 30 patients studied prospectively as measured by

le 1.

The incidence of PDPH in the 260 patients who received labor analgesia with the double technique was one in 260. This was a mild headache which responded to conservative treatmentThe occurence of complications with both techniques is recorded in table 2.

Table 2 Complications a.wxi.ated with labor analgesia complicadon Std Epidtual n=260 double needle n-260

Hypoteasiea 66 4

Failed Meek 20 9

1nwthecat catheter 2 2

Diseussion:Our results indicate that intrathecal fentanyl provides rapid and effective pain relief for an average 102 minutes in the first stage of labor.There is no clinically apparent motor block allowing increased patient moblity.Pruritis was almost aIways seen but was mild and did not require treatment.The cases of hypotension noted cccured almost immediately after administration of the fentanyl and responded quickly to treatmentThe potential advantages of this technique over standard lumbar epiduraI analgesia include almost immediate analgesia without significant motor or sympathetic blockade and the availability of an indwelling epidural catheter for long labors, second stage or cesarean analgesia without significant increase in complications. References: 1. Leighton, BL et al. Anesth AnaIg 69 (1): 122-5, 1989. 2. Gwirtz, KH Anesth Analg 71 (1): 106, 1990. 3. Carrie, LES Br J Anaesth 65:225-233, 1990.

a4

_

_

-

.-

-.

-

_

_..

POSlWlRATIVE PAIN AFTER CW.P.EAN SECTION: EFFECT OF PP.&OPERATIVE SKIN INFILTRATION WITS 0.5% BDPIVACAINE

AUTEORS: PAVY T, GAtiBLING DR, IUIFPRR P

AFFILIATION: DEPARTMItT OF ANARSTWIA, llNIVPJSITY OF BRITISE C0LUHBIA AND GRACE EOSPITAL, 4490 OAK STREEl', VAliCOUVEB, BRITISE COLUHBIA, WI 35 CANADA

INTRODUCTION: Recent studies have suqested that local anesthetic infiltration of skin and subcutaneous tissue along the pmposed incision line prior to surqery iuproves the qaliz a$ duration of postoperative analqesia. studyinq this hypothesis in uouen haVinq

elective louer sequent cesarean section under spinal anesthetic in a randouised, triple- blinded fashion.

Nowever, we have deuonstrated that these patients do report higher pain levels with noveaent. In addition, arbitrary assesssent of analqesia in patients at rest is probably useless on its own, so naxiuun pain scores in the precedinq 24 hours will inpart a wre thorouqb assesssent of analqesic efficacy.

I(ETBoDs: After obtaininq hospital and university ethics conuittee approval, ASA I and II vosen have consented and have been randoaly assiqned to one of tuo qroups. All patients are qiven spinal anesthesia in a standard canner, usinq 249 Sprotte or 25q Whitacre needles and 1 - 1.4 ml 0.75% hyperbaric bupivacaine with 300 ucq $inorph* and 10 nc9 fentanyl. houp A patients then receive 20 - 30 al 0.5% bupivacaine, infiltrated by the obstetrician, along the proposed incision line and doun to fascia. Oroup 5 patients act as a control qroup, and so receive 20 - 30 nl norsal saline by infiltration. The patient, obstetrician and investiqator are all blinded to the solution beinq used. Postoperative data is collected on days 1 - 3, includinq pain assessuent at rest, with aoveuent (turning fron side to side) and the naxinus in the lasl 24 hours, using 1Oca visual analcque scales. VA.9 assessuents are also used to coupare postoperative nausea and pmritus. Tine to first analqesia and total analqesic requires&s are also recorded.

m: Tuenty patients have been studied so far (10 in each group). See Tables 1 and 2. Both croups are conparable in term of age, height, ueiqbt and parity. There are, so far, no siqnificant differences b&men croups in terns of quality or duration of postoperative analqesia.

DISCDSSION: It ms hypothesised that by reducinq (with preoperative local infiltration) the nociceptive impulses which cause a sustained hyperexcitable state in the CUS after a surgical incision, a reduction in postoperative pain levels could be shown. That this bas so far not been the case may be due to the hiqb quality of postoperative analgesia beinq provided by the spinally-actinq opioids.

1. Anesth Anal9 1990; 70: 29-35 2. Req Anestb 1991: 15(1S): 77

__

_

-

.-.

-

-

.~

_

-

Title: DOES BARICITY PLAY A ROLE IN THE INCIDENCE OF SIDE EFFECTS RELATED TO INTRATHECAL MORPHINE?

Authors: WOWFR &, CHADWICK, C., ROSS B., CODA 0.. NICHOLS W.

Affiliation: UNIVERSITY OF WASHINGTON, DEPARTMENT OF ANESTHESIOLOGY RN-lo, SEATTLE, WASHINGTON 98195

. Introduction. lntrathecal morphine (MS) has gained acceptance by many anesthesiologists for treating pain during early labor. The unwanted side effects such as pruritus, nausea, sedation, and respiratory depression are attributed to rostra1 spread of MS within the CSF, resulting in brainstem uptake (1). It is well known that baricity, patient position, and total dose play important roles in local anesthetic distribution within the subarachnoid space. The use of hyperbaric intrathecal MS with placement of patients in a head-up position has been advocated in order to reduce known side effects. However, such recommendations are based on anecdotal experience (2. 3). This prospective, randomized, double-blinded study compares the incidence of morphine related side effects with respect to baricity using hyperbaric or isobaric intrathecal MS in the obstetric population.

Methods: The randomized, double-blinded study was approved by the Human Subjects Research Committee, and written informed consent was obtained from each participating patient. Study patients requesting regional anesthesia in early labor (cervical dilation less than or equal to 4 cm) were randomly assigned to one of two groups. Each group received one of the two following treatments in randomized fashion: lntrathecal MS 0.2 mg diluted to 1 ml with 10% dextrose solution (hyperbaric MS), intrathecal MS 0.2 mg diluted to 1 ml with normal saline (isobaric MS). Immediately following intrathecal injection of one of the two MS solutions via #24 ga Sprotte needle, epidural catheters were placed for later use, and patients were maintained in at least a 30 degree head-up position for 24 hrs. Patients were questioned by a blinded observer at hourly intervals for the first four hours and thereafter every three hours up to twelve hours, for evidence and severity of side effects as well as pain control. No patient participating in the study received addition neuraxial or parenteral opioids. The incidence of pruritus, nausea, and sedation were evaluated by a four point graded scale based upon severity and necessity for treatment. Respiratory depression and urinary retention were evaluated objectively by recording respiratory rate and requirement for urinary catheterization. At this time, the number of patients enrolled does not allow statistical evaluation. Side effect scales related to pruritus. nausea, sedation, and urinary retention will be analyzed by Wilcoxan signed rank test and reported as median (inter quartile range). This test will also be used to evaluate patient satisfaction with pain control. Comparison of respiratory depression will be made using Fishers exact test. A two tailed significance level of 0.05 will be employed throughout.

References: 1. Bromage PR. et al: Rostra1 spread of epidural morphine. Anesthesiology 1982: 56:

431-436. 2. Sidi A, et ahSpinal narcotics and central nervous system depression. Anaesthesia

1981: 36:1044-l 047. 3. Sammi K. et al: Postoperative spinal analgesia with morphine. Br. J. Anaesth.

1981:53:817-820.

86

TITLE: Corprriron of Intrathrarl Hathadone and Psntanyl foe Labor Analgesia

Intrathecal morphine ia known to provide prolonged analgesia. However, due to the la lipid solubility, undesirable sqraspinal effects may occur. Intrathecal fentanyl being a highly lipophllic agent 1, free of such dangerous side effects but the duration of analgesia provided i, tlhorter. Intrathecal methadone is (L m" receptor agonist like morphine and like fentanyl it is highly Upid soluble and therefore is rapidly cleared from the CSP. The purpose of thi, study is to colnpare the analgesic efficacy and the side-effects of intrathecail nbthadons and fentanyl In parturlents requesting aUlgesia for labor. Ilrt-: After obtaining Inltitutional approval and nitten informed Conaeot, 25 healthy prlmigravldae at term, requesting epidural analgesia for labor =re studied. TRY were randomly assigned to receive either lntrathecal mathadons 1 rq (group Ml, n-8). 2 q (group m, n-8) or featMy 25 ug (group P. n-9). A combined spin.a-epiduaL technique "a¶ perfornad as follows; initially, M 18 gauge touhy needle "as inserted at the L3-4 or L2_3

interspace and a 24 gauge, ,ZOnrm long spinal needle "a, advanced through the epidural noodle into the subarachnoid Space. After obtaining clear, free flor of CSF, the study drug diluted to a volume of 1 ml "a?1 inyected intrrthscally and the spinal needle "as withdram. A catheter was threaded 2-3cm cephalad into the spfdural space for subsequent injection of local anoSchetlcs at patient's requsst for additional analgesia. The patients rated their pain on a 1Ocm visual analogue scale (VAS) every 5 minutes for the fir,t 15 minutes, every 15 minutes for 60 minutes and every 30 minutes until additional analgesia was t-stted. MaternzJ BP, W? and RR verb retarded every S minutes along with fetal heart rate, uterine contractions, and the progress of lab-x were assessed frequently. The onset and degree of sensory and motor block were assessed and the incidence of ,ida+ffect, such a8 pruriti,, nausea and vomiting and ~xco,,~"o sedation was recorded. The time and mods of delivery, neonatal Awar scores and VA and WV blood gases and the incidence of porrt dural puncture headachs (PDPH) “ere recorded. Statistical analysis "a, performed using chi-square analysi5, and ANOYA and p<O.OS m)re considered significant. trrrltr : The patienta in the three groups "ere sLmi1a.r in age, height, weight, parity and gestationa age. Tkere were no differences in maternal vital signs, progress of 1abor. and the mode of delivery. Nausea. vomiting and respiratory depressions were absent in all groups. Incidence of pruritfs "as similar in all groups. The time of onset of analgesia (US-O) was similar in the three groups (Fig. 1). Ho"e"er, the duration of analgesia was significantly prolonged in the wthadons groups compared to fentanyl group (group "1-150.62 f 22.74 min. group M2 - 180 t 20.9 min. group F I 82.22 * 15.8 n&n p <o.ooor). NOllO developed PDPH. Neonatal Awr score, and DA and UV blood gases ~*bre similar in all groups. Cor1uiom: Intrathscal msthadone provides significantly prolonged labor a,,a.lgosia compared to intrathecal fentanyl rith minimal Side-effects.

-

.- a7

Title: MATERNAL AND NEONATAL EFFECTS OF CONTINUOUS INTRATHECAL SUFENTANIL FOR LABOR ANALGESIA

Authors: R Sharp, MD, TR Abbcud, MD, J Zhu, MD, c Rosa MS, C LaGranae. MS. B Kassel. MS

Affiliation: Department. of Anesthesiology, Los Angeles County+University Of Southern California Medical Center, Los Angeles, California 90033

Introduction: Intrathecal morphine provides good maternal analgesia during labor but is associated with a high incidence of side effects presumably due to rostra1 spread in the cerebro- spinal fluid. Sufentanil has high lipid solubility which should limit its rostra1 spread and side effects. The present study was undertaken to evaluate the efficacy and safety of intrathecal su- fentanil for labor analgesia. Methods: Fifteen healthy parturients at term were studied after approval by the Institutional Revlew Board and informed consents. 28G spinal catheters (Kendall CoSpanTm) were inserted via 22G sprotte needles at L2-3 or L3-4 interspace. When patients re- guested pain relief 5ug preservative-free sufentanil in 1 ml volume of normal Saline was given. the Visual Analog Scale.

Analgesia was evaluated using Motor block, fetal heart rate, uterine

activity, duration of labor, maternal vital signs and the incidence of side effects were also noted. Neonates were evaluated by Apgar Scores at 1 and 5 min, cord acid base status and the Neo- natal Adaptive capacity Scores (NACS) at 2 and 24 hours of age. Results: are presented in the table and graph and they indicate that intrathecal sufentanil provides fast and good analgesia during labor but is associated with tachyphylaxis after the first dose. Discussion: Intrathecal sufentanil provided good labor analgesia but was associated with tachphylaxis not previously reported with its use (1,2). These results indicate that sufentanil is suitable if labor is anticipated to be of short duration as in multiparous women or primiparous women close to delivery. Our high incidence of instrumental delivery deserves further investigation with a larger study group. References: 1) Nautly JS, Becker DB, Pate A: Anesthesiology 73: A964, 1990. 2) Leicht CH, Evans DM, Durkan NJ: Anesthesiology 73: A981, 1990.

Table Onset of Analg. (min): 4.02.7 Duration (mean+SaJ) min:

Graph

1st injection Tn=15) 162+19 CONTINUOUS SPINAL SUFENTANIL FOR LABOR

2nd injection (n=ll) 87T17 3rd injection (n=lO) 45?15

; 1or q,

Total Dose (ug) : 8

Side Effects (%I: Hypotension 2 (13%) 13il i lb/

Nausea or Vomiting 1 (7%) Pruritus (no treatment)14 (94%) g Spinal headache 1 (7%) Aqar Scores (%) 6 or Less: 1 min

T

Mode of Delivery: Spontaneous 9 (60%) Forceps or Vacuum 2 (13%) Cosarean 4 (27%)

TITLE: THE USEFULNESS OF CONTINUOUS SPINAL ANESTHESIA FOR CESAREAN DELIVERY IN PREECLAMPTIC PATIENTS.

AUTHORS: Shreeniwas Jawalekar, MD* William A. White, Jr., CRNA, MS

AFFILIATION: Anesthesiology, Charleston Area Medical Center, 800 Pennsylvania Ave., Charleston, WV 25302.

Introduction: Continuous spinal anesthesia (CSA) has certain advant?ges which make it a useful technique in high risk patients. CSA has been used successfully for cesarean delivery." Our experience with 20 cases of CSA for cesarean delivery in preeclamptic patients is presented. Methods: After Institutional Review Board approval and informed consent, 20 patients who underwent cesarean delivery under CSA were studied. Lumbar puncture was performed at L2-3 or L3-4 with the patient sitting, using a 22-gauge needle inserted with bevel parallel to dural fibers. A 28-gauge nylon catheter was placed in the subarachnoid space and advanced cephalad for 3 cm. The patients were positioned for delivery with left uterine deviation. Surgical anesthesia was achieved with incremental doses of intrathecal lidocaine and fentanyl. Preservative-free morphine was given intrathecally for postoperative pain control. The intrathecal catheter was removed on the morning following surgery. The following observations were recorded: 1) fluid preload, 2) time from injection of anesthetic to incision, 3) dose of lidocaine, 4) blood pressure changes, 5) incidence of postdural puncture headache (PDPH), and 6) Apgar scores. Results: In all cases the spinal block was successful. The mean (2 SD) preanesthetic fluid load was 264 (2 117) mL of Ringer's lactate. There was no incidence of high spinal or of abrupt fall in blood pressure. The mean time from injection of local anesthetic to incision was 10.6 (2 4.1) minutes. The total mean dose of lidocaine required was 33.3 (+ 10.0) mg and that of fentanyl was 14.5 (+ 4.6) mcg. None of the patients complained of PDPH. Mean Apgar scores at 1 and 5 minutes were 7.6 (+ 1.3 ) and 8.9 (f. 0.8). Conclusions: CSA provided safe, effective surgical anesthesia for the patients in this study. A combination of local anesthetic and opioids was used for subarachnoid block. The requirements for lidocaine were surprisingly low. Mini-dose morphine provided excellent postoperative analgesia. PDPH did not occur. We believe this to be due to an inflammatory response as described by Denny et a1.3 References: 1. Underwood RJ: Experiences with continuous spinal anesthesia in physical status group IV patients. Anesth Analg 47:18-26, 1968. 2. Bizzarri D, Giuffrida JG, Bandoc L, Fierro FE: Continuous spinal anesthesia using a special needle and catheter. Anesth Analg 43:393-399, 1964. 3. Denny N, Masters R, Pearson D, et al.: Postdural puncture headache after continuous spinal anesthesia. Anesth Analg 66:791-794, 1987.

89

-

._

__

TITLE: ARE ECG CHANGES DURING CESAREAN SECI-ION (C/S) MERELY DUE TO CARDIAC SYMPATHETIC BLOCKADE?

AUTHOR: Aaron Stein, M.D.*, James C. Eisenach, M.D.

AFFILIATION: Department of Anesthesia, Wake Forest University Medical Center, Winston-Salem, North Carolina

Introduction: ST segment depression has been noted in up to 30% of women undergoing C/S with spinal or epidural anesthesia. Ischemia seems an unlikely cause in this healthy population with normal echocardiography during these episodes of ST depression. Since blockade, especially asymmetric blockade of cardiac sympathetic efferents alters repolarixation, we speculate that these changes may be due to sympathetic blockade from spinal or epidural anesthesia. We therefore compared women with and without ST segment changes during C/S for cardiac sympathetic tone, utilizing a recently described technique, spectral analysis of R-R intervals.

Methods: After IRB approval and obtaining informed consent, 5 of an eventual 20 healthy women undergoing C/S with spinal bupivacaine anesthesia were studied over a 6 week period. A QMEDm monitor was used to digitally record both a lateral and precordial ECG beginning 1.5 min before institution of the block until the block had resolved. This ECG record was analyzed for significant (> lmm) ST segment depression, and R-R intervals measured for 256 beats prior to blockade and 10 min after spinal injection. R-R intervals were processed by fast fourier transform and integrated area in the region ascribed to cardiac sympathetic activity (0.04-0.12 Hz) calculated. We also measured blood pressure (BP), heart rate (HR), drug use, and sensory levels. Data are expressed as mean c SD and will be analyzed with t-tests.

Results: Sensory blockade to pinprick was between T4 and Tr bilaterally in all cases. Of the 5 patients 2 had ST segment depression, occurring within 10 min of spinal injection, unrelated to changes in BP, HR, or ephedrine use. One patient without ST segment changes was excluded due to marked sinus arrhythmia after block. Power analysis reveals that should these results

Table I: Cardiac Sympathetic Tone: Area Under PowerxFrequency Curve .04-.lZHz

PRE ST DEP. BLOCK No (n=2) 8.7k8.2 Yes (n=2) 3.920.8

POST BLOCK 1.2 + .06 0.4 2.07

continue we will be able to demonstrate less power in the sympathetic region in those with ST segment depression than those without 10 min after spinal injection.

Discussion: These data support previous studies demonstrating a high incidence of ST segment depression during C/S under spinal anesthesia, unrelated to BP, HR. or adjuvant drug use. Despite similar levels of sensory blockade to pin testing, these preliminary data suggest that differences in the density of upper thoracic sympathetic blockade may account for the changes in cardiac repolarization seen at C/S.

90

_

TITLE: An improvement in spinal and epidural anesthesia for cesarean section.

AUTHORS: Swami A, Abbott P, Morgan BM. AFFILIATION: Queen Charlotte's Hospital, London, UK.

INTRODUCTION: Combined spinal-epidural (CSE) technique allows a reduction of the spinal dose as neural blockade can be extended and prolonged via the epidural catheter when necessary. We ascertained the lowest spinal dose that the presence of the epidural catheter made practical and compared it with our standard single shot spinal dose. METHODS : Parturients scheduled for elective cesarean section (c/s) were randomised to receive subarachnoid 7.5mq or 12.5mq hyperbaric 0.5% bupivacaine plain. After 1L Ringers preload, a 16G Tuohy needle was placed in the epidural space at L2-3 interspace with the patient in the left lateral position. A 27G quincke tip 12cm B-D spinal needle was passed through it to perform the subaraohnoid injection (SAI). A catheter was inserted into the epidural space, secured, and patient turned to right lateral position immediately. A blinded second anesthesiologist maintained normotension with an ephedrine infusion[l] and tested the spinal block at 5 and 10 minutes. If it was below T4 at lOmins, 1Omls epidural top-up was given (Bupivacaine 0.5% + liqnocaine 2% + 1:200,000 epinephrine). Epidural fentanyl 1OOmcq diluted in 1Omls of saline was routinely given prior to start of surgery. Post-operatively, epidural diamorphine 3.5mq in 1Omls saline was given when the block was at T6 with knee flexion. Statistical analysis of results was using t-test and chi-squared test: p<O.O5 being significant*. _ Results: There was no difference in age, weight, height and C7-sacral hiatus length in the two groups. No patient required intraoperative analgesia. There were no spinal headaches or other complications from the technique.

TABLE I 7.5ma 12.5ma

Number of patients Block to T4 at 1Omins

n(%)- n(8) -

::,77, 45 45(100)

Pre-op epidural top up lO(23) 20% fall in BP lO(22) 1:: 4:; *

Mean+SD - Mean+SD

SAI to end of surgery (min) 67.3215.6 61.3+12.1* Recovery to T6 and knee flexion (min) 107.1+20.0 147.4T23.9* Umbilical vein pH 7.31+0.07 7.32TO.04 Umbilical artery pH 7.27zO.07 7.27zO.05

Conclusion Advantages of CSE techniques are rapid excellent anesthesia with a small dose SAI and epidural top up when necessary, less hypotension, quicker recovery time from the block and efficacy of postoperative epidural opiate analgesia. Disadvantages are an acceptable delay in commencing surgery and a slightly more complicated technique. References [l] Kanq et al. Anesthesia and Analgesia 1982:61:839-842.

91

Title:

Authors:

Affiliation:

Comparison of sufenta.bupivicaine and bupivicainei sufenta for epidural anesthesia in labor.

M.Tmer M.D..W.Kwan M.D..B Chen M.D.

Department of Anesthesiology Harbor-UCLA Med Ctr Torrance.California

Introduction. Combining an opioid and a local anesthetic enhances epidural anesthesia and decreases the sympathetic blockade and hypotension which occur with higher concentrations of local anesthetics.The aim of this study was to CornPare the efficacy of low concentration of S(Bupivicaine) and high dose of S (Sufentanil) alone or in combination for labor epidural analgesia.

Methods. Institution Review Board and informed consent were obtained. Sixty healthy parturients were randomly assigned to one Of four groups. Group 1 (n=15) received normal saline.group 2 (n=15) received 0.06% B.group 3 (n-15) received 20 mcg S and group 4 (n=15) received 0.068 B plus 20 mcg S. All patients were prehydrated with 1000 cc of LR and a continuous epidural catheter was placed in a standard manner. The study solution(l2cc) was given if test dose was negative after 3 min. Patients were asked to assess their pain every 5 min for the first 30 min and every 15 min thereafter using a VAS. Maternal blood pressure and heart rate.onset of pain re1ief.senscu-y level and motor blockade, duration of analgesia(758 of original VAS).method of delivery and neonatal Apgar scores were recorded. Patients were observed closely for side effects. Patients with pain score greater than 6 after 20 min were given an additional 5 cc of 0.25% B and were not used in the calculation of the duration. Data from the groups were compared using unpaired Students t-test and ANOVA. P less than 0.05 was considered significant.

Results. Results are shown in the table below. There was no difference among the four groups vith respect to demographic data. Two patients (one in group 3 and one in group 4) had mild pruritis that resolved with 25 ng of benadryl IN. Four patients (two in group 2 and two in group 4) had transient hypotension which responded to IV ephedrine. No one had a motor block.

Discussion. The results of this study show that excellent analgesia with quicker onset and longer duration were achieved when sufentanil alone or in combination with bupuvicaine were used. The quality of analgesia was better than that achieved with 0.06% bupivicaine alone and the benefits to the mother of using sufentanil are not offset by any adverse effects on neonatal outcome. The incidence of hypotension and it's dele- terious effects on the fetus are avoided when 0.06% is used.

NS B S B+s GPl(n=15) GP2(n=15) GP3tn.15) GP41n=15)

n.patients pain free at 10 min. 2 S

. . 10" 12"

n.patients pain free at 30 nin. 2 10" 13" 14" Durationcmin) +SD 3029 90+16'.

n=6 n=14 135tlS"' 140+17*.*

- n=l3- "'PL 0.05: significantly differrent from NS or B

n=15-

"pL0.05: signifantly different from NS

REFERENCE: 1. Naulty Js during labor

et al: Epidural Sufentanil-bupivicaine for analgesia and delivery. Anesthesiology 71:AB42,1989.

92

IMPLEMENTATION OF CRITICAL CARE OBSTETRICS

NAN H. TROIANO,R.N.,M.S.N.; JULIE MARTIN,R.N.C.,M.S.N.; RICHARD L. ROSEMOND, M.D.; PRANK H. BOEHM, M.D.; CORNELL4 R. GRAVES, M.D.; HELEN V. JOHNSON,M.D.;*

AND JOHN W. DOWNING, M.D.*

DIVISION OF MATERNAL-PETAL MEDICINE AND DIVISION OF OBSTETRIC ANESTHF!SIA(*)

DEPARTMENT OF OBSTETRICS & GYNECOLOGY, VANDERBILT UNIVJZRSITY MEDICAL CENTER

NASHVILLE, TBNNBSSEE

Capabilities for provision of critical care were developed within the labor and delivery area of a tertiary care facility. Preparation for the unit included identification of a core nursing team, education of resident physicians and nurses, and purchase of state-of-the-art hemodynamic monitoring equipment. A multidisciplinary approach to patient care was implemented which included maternal-fetal medicine, obstetric anesthesia, nursing services, and other specialty consultants when indicated.

During a one-year period, fifty-eight patients were managed in our obstetric intensive care unit. The majority of patients were undelivered at the time of admission (78%) with a mean estimated fetal gestational age of 30 “’ weeks and had been transported from outlying community hospitals (77%). The primary admission diagnosis was severe pregnancy-induced-hypertension (PIH - 50%). Associated complications demonstrated by patients within this group included HELLP syndrome (21%) eclampsia (14%), pulmonary edema (ll%), and DIC (4%).

Medical problems during pregnancy accounted for 38% of patient admissions. Multiple admission diagnoses were common in this group. Massive hemorrhage was responsible for 9% of admissions. Patient management included use of several procedures not frequently utilized in obstetrics including radial artery catheterization (82%), pulmonary artery catheterization (40%). mechanical ventilation (22%) hemodiiysis (3 %), and intracranial pressure monitoring (1.5 W). There was one maternal death (I-C bleed) in the year, yielding a maternal mortality rate of 1.7%. There were no cases of antepartum stillbirth. We conclude that critically ill pregnant women may be successfully managed in an obstetric intensive care unit using a multidisciplinary, ‘PERINATAL TEAM’ approach.

-

93

-

_-

.-

.~..

-

Intravenous Nalbuphine Increases Subsequent Analgesic Requirements of Continuous Spinal Analgesia for Labor

G. M.Vasdev,M.B.B.S.; C. H.Leicht,M.D., M.P.H.

Department of Anesthesiology, Mayo Clinic, Rochester, MN

Intraduction: lntrathecal sufentanil has been previously shown to be an effective method of analgesia for labor.‘,2 We allow patients to choose between continuous spinal analgesia (CSA) with sufentanil and continuous epidural analgesia(CEA) for routine labor. For CSA, it is our practice to give repeated boluses of sufentanil via a microcatheter supplemented with small doses of lidocaine as necessary. Nalbuphine has gained popularity among obstetricians as an analgesic for early stages of labor and is frequently administered to parturients prior to anesthetic intervention. Although CSA provides excellent analgesia for many patients, it was our observation that the effectiveness of CSA with sufentanil seemed to be decreased in patients who previously received intravenous nalbuphine. Methods; 28 g continuous spinal catheters (Co-SpanrM, Kendall) were placed in 23 patients who requested CSA for labor analgesia. All received initial boluses of 15 ug of sufentanil and thereafter given increments of sufentanil and/or lidocaine to maintain adequate analgesia. Group 1 patients (n=ll) received 210 mg intravenous nalbuphine and were compared with Group 2 patients who did not receive nalbuphine (n=12). Data collected and compared included: age, parity, height, weight, duration of labor, and the total amount of sufentanil and lidocaine required. Data was compared utilizing paired student t-tests with a p value I 0.05 considered significant. Results: There was no statistical difference in age, parity, height, and weight between the two groups. Furthermore, there was no difference in the duration of labor: 287.7 + 164.5 versus 280.4 + 168.5 in Groups 1 and 2, respectively (minutes, mean + std dev). The amount of sufentanil required appeared greater in Group 1, 40.7 f 22.7 versus 34.5 + 14.3, (pg, meankstd dev) but did not reach statistical significance. Lidocaine requirements, however, were much greater in Group 1, 31.9 + 16.2, compared with Group 2, 13.75 + 17.9 (mg, mean + std dev) which was statistically significant. Additionally, 4 patients in Group 1 required additional forms of analgesia, as CSA with sufentanil was not effective in these patients who had previously received nalbuphine. In contrast, CSA with sufentanil provided adequate analgesia in all patients in Group 2. Dlscusslon: CSA with sufentanil alone was inadequate in many patients in Group 1 necessitating increased lidocaine doses which is undesirable in laboring patients because of concomitant motor blockade. As the analgesic pathway for spinal opioids is mediated through receptors,3 prior administration of an agonist/antagonist drug(nalbuphine) may interfere with the effectiveness of subsequent spinal narcotic administration. Prior administration of nalbuphine has not been reported to effect subsequent CEA for labor: most likely because that technique almost uniformly utilizes some local anesthetic and is not dependent solely upon the effect of the narcotic that may be present in the epidural solution. It appears that nalbuphine should not be administered to patients who are likely to receive CSA with narcotics for labor.

1. Naulty, et al: Anesthesiology 73: A974! ,199o 2. Leicht, et al: Anesthesiology 73: A981, 1990 3. Cousins, et al: Anesthesiology 61: 276-310, 1984

94

,-

-.

,_

EPIDURAL ANESTHESIA FOR POSTPARTUM TUBAL LIGATION USING EPIDURAL CATHETERS PLACED DURING LABOR

Authors: Vincent RD, Reid RW Institution: Department of Anesthesia, University of Iowa College of Medicine, Iowa City, IA. 52242

Introduction: An advantage of epidural anesthesia for labor in women who desire sterilization after delivery is that epidural catheters used during labor may be left in place and reinjected later to provide anesthesia for postpartum tubal ligation. Unfortunately, we have observed that epidural anesthesia is often unsuccessful when these in-situ catheters are reinjected just before surgery. The purpose of this study was: 1) to evaluate the success of epidural anesthesia for postpartum tubal ligation using epidural catheters which were placed during labor; and 2) to determine whether patient characteristics, technical factors (e.g., the length of epidural catheter inserted into the epidural space), or the interval between delivery and surgery influenced the success of subsequent epidural anesthesia. Methods: After IRB approval, charts were reviewed for 69 consecutive women scheduled for elective postpartum tubal ligation using epidural catheters which had been placed during labor. Twenty-gauge closed-tip triple-orifice epidural catheters (Burron, Bethlehem, PA.) were placed during labor in all parturients. Subsequent epidural anesthesia was defined as successful (i.e., adequate patient analgesia was achieved with epidural local anesthetic alone, or in combination with intravenous opioids and/or inhalation of NsO/Os) or unsuccessful (i.e., the epidural catheter became dislodged before surgery, or the catheter was reinjected but spinal or general anesthesia using a potent inhalational agent was required to achieve adequate intraoperative anesthesia). Statistical analysis was by unpaired t-tests. PcO.05 was considered statistically significant. Results: Epidural anesthesia for postpartum tubal ligation was successful in 74% (50/66) of women. The interval between delivery and tubal ligation was less (P=O.O4) in the successful group than in the unsuccessful group (table). Variables which tended to correlate with unsuccessful epidural anesthesia included: increased patient weight, increased body-mass-index (BMI) (Wt[kg]/Ht[m]2), and an increased length of the second stage of labor (P>O.O5 each) (table). The length of epidural catheter inserted into the epidural space was not significantly different between the successful and unsuccessful groups (4.2 ? 0.1 and 4.0 F 0.2 cm, respectively).

Deliverv-PPTL fhl m BMI Ikalm71

Successful (n=50) 10.8 * 1.1 77*2 28.7 -r 0.6 33F4

Unsuccessful(n=18) 15.2i1.7' 83?4 30.3 + 1.2 47t12

f PcO.05 versus successfulgro"p

Discussion: Although other factors may influence the timing of postpartum tubal ligation after delivery, the success of epidural anesthesia for tubal ligation using in-situ epidural catheters is greater if surgery is performed shortly after delivery.

95

_

.-

Title: POST-CESAREAN PAIN RELIEF WITH KETEROLAC TROMEHTAMINE AND EPIDURAL MORPHINE

Authors: J. M. Hullander, M.D., A. Kraft, M.D., G. Whitten. M.D., G. Burger, M.D.

Affiliation: Department of Anesthesiology, Naval Hospital, San Diego, 92134-5000

Introduction: Epidural morphine (EM) is a common method for managing post-cesarean section pain, however it is associated with multiple undesirable side effects. The purpose of this study is to determine whether a reduced dose of EM supplemented with keterolac tromethamine (KT) can provide equivalent post-operative analgesia with fewer side effects. Methods: This study was approved by the Institutional Review Board and written informed consent was obtained from all patients. Twenty seven healthy parturients underwent elective cesarean section, anesthetized with epidurally administered lidocaine 2% or bupivacaine 0.5% and then randomly assigned to three groups. Group 1 (Gp.1) received KT 60 mg IM when adequate uterine tone was achieved, followed by KT 30 mg IM every 6 hours for 24 hours. A saline placebo was given via the epidural catheter. Group 2 (Gp.2) received 2 mg EM and the same KT regimen as Gp.1. Group 3 received 5 mg EM and IM saline placebos. During the next 24 hours, pain, nausea and pruritus levels were recorded using a visual analog scale (VAS). Pre-operative and three day post-operative hematocrit, and the need for supplementary pain medications were noted. Results: A total of 8, 9, and 10 patients were included in Gp.1, Gp.2, and Gp.3 respectively. Pain relief was significantly greater in Gp.'s 2 and 3 than Gp.1. Nausea and pruritus was significantly less in Gp.1 than in Gp's 2 and 3. No statiscal difference was found between pre- and post- operative hematocrits.

Pain Nausea Pruritus

Discussion: Keterolac provided significantly fewer side effects, however, it provided inadequate pain relief. Reduction of EM with supplementary Keterolac did not significantly improve pain relief nor reduce the severity of side effects. Based on this study we do not recommend the substitution of keterolac for a reduction of epidural morphine.

96

.-

-.

--

Title: HIGH SPINAL ANESTHESIA,FOLLOWING FAILED EPIDURAL ANESTHESIA FOR CESAREAN SECTION

Authors: J. Waters. M.D., B. Laverty, M.D., T. Scanlon, M.D., G. Burger, M.D.

Affiliation: Department of Anesthesiology, Naval Hospital, San Diego, 92134-5000

Introduction: Our experience has shown that unexpectedly high spinal blockade may occur following failed epidural anesthesia in the obstetrical population. Only one case report was found to corroborate this anecdotal experience.i We decided to retrospectively study this problem. Methods: Anesthetic records from the previous 12 months were reviewed. The records of seventeen patients who had received a bupivacaine spinal anesthetic following a failed epidural anesthetic were found (Gp.1). The records of a matching group of patients having received a bupivacaine spinal anesthetic alone were randomly collected from the same time period (Gp.2). Data collected from the anesthetic records included the patients' age, height, weight, position, bupivacaine dose, highest recorded spinal level and the volume of the injected spinal anesthetic. Level was assigned a number O-30 according to its proximity to the fifth caudal dermatome (assigned the number 1). Data was analyzed using the Mann-Whitney U test. Results: The incidence of high spinal blockade resulting in respiratory compromise was l/17 in Gp. 1 with none reported for gp. 2. An equal number of patients received their spinals in the sitting versus lateral position. Both groups were simi

* P40.02 DISCUSSION: Because of a common fear of high spinal amongst our anesthesiologists, they typically reduce their dose in Gp.1 type patients. In this review we found a significantly larger dose and volume in Gp.2 patients, however, the levels achieved were similar. Because a similar level was obtained using different doses and volumes, a ratio of level/dose and level/volume was calculated. These ratios strongly suggest that a higher dermatomal level will be achieved with commonly recommended spinal doses following a failed epidural anesthetic. Further investigation of this problem is ongoing. References: 1. P.A. Stone, J. Thorburn, K.S.R. Lamb; Br. J. Anaesth. (1989), 62, 335-337

97

Title: The Impact of Epidural Analgesia on Obstetrical Practices in a Small Community Hospital

Authors: Willian, D., Campbell, C. Affiliation: Department of Anesthesia, Indiana University School of Medicine,

Indianapolis, Indiana

Introduction. The influence that epidural analgesia has on the mechanics of parturition has been hotly debated for many years. Previous studies have been criticized because of various methodologic flaws. Adequate control of the study population to match control groups has proven particularly difficult to achieve. Our aim in this study was to eliminate, as much as possible, inherent bias and assess the impact that initiation of an epidural service had on the progress of laboring patients in an otherwise static environment.

Methods. The study location was a small, low-risk obstetric unit in a community hospital. Obstetrical anesthesia coverage had been upgraded to 24 hour “in house” availability several months prior to our review. We retrospectively reviewed the charts of 824 patients who had undergone vaginal deliveries of term infants following uncomplicated pregnancies - 436 parturients prior to epidural availability (Pm-EPI), and 388 parturients (Post-RF’11 that were delivered after establishment of the service. Information was sought to determine the frequency of malrotation, oxytocin augmentation, ‘assisted’ delivery, cesarean section, and average duration of labor in each of these groups. The data was subjected to statistical analysis.

Results:

l p < 0.001 vs. no epidural

Conclusions. Our results indicate that effective pain relief for labor and delivery was afforded at significant cost to the normal mechanics of parturition.

98

m:

a: Aftilistion:

A COYPARfSON OF TWO DOSES OF EPIDVRAL FENTANYL FOR CESAREAN SECTION “SfNG

CARBONATED UDOCAtNE I. Yes MD FRCPC. S. Halper” MD FRCPC, R. Pitfini, C. Huh

Dapanms”, of Anassthssia. Worn*“‘* CoIIege Hospifal and Univsrsity of Tamto. Tccfea. &U&J

INTRODUCTION Epiduraf fa”,a”vl (EFI. SO 10 100 pg. has bee” show” IO improve rhs quality of anesthesia for

cesarea” section CS) wha” added to Ioca1 a”assths,icW Side effects such as drowsiness and nausea are common

with these do*es. I” this srudy. we cornpar** fhr) *ffec,ive”ess and incidence of side eff*c,* at 25 pg YZ SO pg of EF

in a ra”damizsd doubts blind prospsctive manner.

METHODS After Ethics Comminsa approval and informed consent. 50 patianrs having elscbva CS under spidursl

anesthesia were randomized into ,WO groups. Aft.% a standard ,(ls, dose. patients in Group I IN = 24 received 25 #,D

of EF in B 1 ml voIume and Gmuo It IN=261 received SO#g in the s8me fashion. Continuous apidursl anesthesia was

induced “sing 2% carbonated lidocaina with

1:200.000 s,,ins@ins. ,i,ra,ed 10 a T, ssnsory

I.v.I. The qualiry of analgasis was measured by

the need for s”~~lsmsn,al I” ‘entan, intra-

werfati~ely, by visual analogus psi” scores

WAS,. and by the Short Form McGill Pain

(lussrionnsirs (SF-MPW immsdiatsly post-

opera,ively. The incidence of side effects such L)S

hypofsnsio”. drowsiness. nausea. ,,rud,“s. and

ms~~ra,ov, depression was also rscordad.

Neonates were assessed using 1 and S minu,~

Apgar scores and umbilical cord gases. All

recordings were made by a blinded observer.

Demographic data were a”al”,sd using the

““pairad Student’s ,-10s~ Analgesia and side

affects were compared using the Fisher’s EXaC,

test and ““paired 1.test where ~p,w,pria,e. A P

value <O.OS was considered significant.

RESVLTS The sfudy groups did “0, differ in age.

height. or weigh,. Surgical charectsristics.

TASLf

snssrhstic requireme”,s. and rids effects were

similar in both groups ITablal. Mea” VAS pain scores IFigure 1) and SF-MPO snores IFiwre 2) did no, differ

~“ificantly. There were no diffsrsncas in birth wsigho

Visual Analogue Scores

,psr scorss. and cord blood gases bstwsa” ,h., ,WO groups.

McGill Pain Scores

30 :‘““’ *=“‘- 91 I a/ I 7~ !

FIGURE 2 DISCUSSION The r.s”lts of this srudy show no significant differences between the IWO groups in the quality of

analgesic. es measured by each of the three methods described. Group I C25pgl showed a tendency towards grea,er

need ‘or su~~le”w”,al I” ‘sntanvl. higher c-sin scores. and le.. “a”sea than Group II 150 ,,,8,. but these di‘tsrsnees

were no, s,a,is,i~a,ly significant. Use of ,he I0w.r doss of EF did no, signi‘icandy reduce rhe incidence of side effects,

pa~ieularly drowsiness. Although 25 pg of EF appears to offer similar analgesia fo SO pg for cesarea” section. it has

“0 other advantages 10 recommend its routine use. This swdv supports the use of 50 pg of EF for cesarea” section

as B safe and et‘sctivs dose.

REFERENCES

I. A”aes,h Intens Cars 1390: IS: 22-30.

2. Anesthesiology 1988: 68: 938-43.

3. Can J Aneesth ,988: 35: Sl IO-51 II. 4. Pain ,987: 30: 191-7.

99

.-

Title: SPINAL NEEDLE FLOW COMPARISON

Authors:Barbara Zucker-Pinchoff,MD; Margaret Ruttenberg,MD

Affiliation: Mount Sinai Medical Center, New York, N.Y.

Introduction: Many sizes and types of spinal needle are currently

available. Aside from reducing the incidence of post-durai puncture headache (PDPH) to an acceptable level1 2, spinal needles must also be scrutinized for clinical ease of use. It is clear that rapid return of CSF, with easy aspiration, makes the institution of a spinal block easier, faster,and more reliablea. The rate of flow through a needle is dependent on many factors such as internal diameter, length, size and type of hole,and turbulent versus laminar flow. Rather than try to compare these many elements, we compared the rate of flow through a variety of needles. Conditions were identical for all needles, so comparisons should be valid. Materials and Methods:

We connected a 20ml syringe with the plunger removed to a short length of connecting tubing and then a hep-lock cap with a rubber diaphragm, as shown.The whole unit was then taped to an IV pole to keep it upright.

I 63 After filling the

apparatus with 0.9% saline, the rubber diaphragm was pierced with the needle to be tested. The distance from the fluid meniscus to the end of the needle was measured at 35 cm. The apparatus was slightly over-filled, and as the fluid _I=

Pressure tubing

meniscus passed the 10 ml mark on the syringe, aacm 1

timing was begun. Five ml of fluid were allowed to drip out of the needle hub, and as the meniscus passed the 5ml mark on the syringe, time elapsed was recorded.

Hep-lock COP

Results : 22 ga Quinke 8.89 cm length 2’ 36”

Spinal

22 ga Whitacre 8.89 cm length 2’ 25” needle

24 ga Sprotte 9.0 cm length 5' 05" 25 ga Quinke 8.89 cm length 15’ 51” 25 ga Whitacre 8.89 cm length i 3 a 37 ‘I I -_-.-_.

27 ga Quinke 8.89 cm length 35’ 32” 3

Discussion: s

The results of our study are not surprising: the larger the needle, the faster the flow. The difference which interested us was the approximately three times greater flow rate through the Sprotte 24 ga needle compared with the 25 ga needles. We conclude that the faster flow, combined with the the much lower incidence of PDPH4 support use of the Sprotte, in spite of its extra cost. References:l.Anesthesiology 73:A1003 2.Anesth Analg 72:575 3.6r J Anaesth 59:1465-71 4.Anaesthesia 45:656-a

100

. .

TITLE: QUALITY OF DIFFERENTIAL SENSORY BLOCKADE AND LASOR ANALGESIA WITH CONTINUOUS EPIDURAL INFUSIONS OF BUPIVACAINE AND FENTANYL

AUTBORS: J.H. chunq, N.D.; .T. Travis, M.D.; R. Sinatra, M.D., Ph.D.; T.Z. o'ccnncr, H.P.E.; S.J. BrUll, M.D.

AFFILIATION: Aces. Dept., vale University school of Medicine, Yale- New Raven Eospital, New Raven, CT 06510

The goal of labor analgesia is to provide optimal pain relief with minimal risk to mother and fetus. In this regard, a continuous epidural infusion technique (CEIT) with low concentrations of bupivacaine (BLIP) + fentanyl (PENT) has been advocated.' ~cwever, varying degrees of sensory and motor blockade have been noted depending upon the BUP CcncentratiCn. This study evaluated the width of zcnes of differential autonomic, sensory, and motor block that occur during CEIT administration of twc different BUP and PENT solutions, and determined their analgesic efficacy.

After IRS approval, 52 healthy nulliparous parturienta in active labor (3-6 cm cervical dilatation) gave informed consent. Following prehy- &&ion, the epidural catheter wes inserted at L,_, interspace and 5 ml of 0.5% SUP with epinephrine 1:200,000 was administered ever 5 min as two test doses for subarachnoid and intravascular injection, followed by 50 pg of FENT in 10 ml of normal saline. When adequate analgesia was achieved, the CEIT was started at 20 ml/hr with one of two mixtures, in double-blind fashion: Group A: 0.125% BUP plus 0.00025% FENT; Group 8: 0.0625% BUP plus 0.00025% PENT. sensory levels were determined every 20 min for the 1st hr. and then hourly for the next 3 hrs. DerriatCmal levels of lose Of tempera- ture discrimination (TE), pinprick (PP), light touch (LT) and vibration (VI) sensation, and level of motor blockade were determined by 1 of 3 observers. III addition, incidence of pruritus and analgesic quality of block were assessed using 10-m visual analog scale (VAS) score for pain (O=no pain, lO=wcrst pain) and satisfaction (O=none, lO=ccmplete). Data were analyzed with chi-square, signed rank test, and ANOVA with Tukey's adjustment. ~~0.05 wee considered statistically significant.

Patient demographics were similar (P=NS). Median thoracic (T) dematomal levels for Group A were T, for LT, T,., for PP, T, for TE and T, for VI. corresponding values for Group B were Ts.S, T,, T, and Tg. Width of zcnee of differential blockade developed at the end of the third hour of CEIT are shown in the table. P-NS for width of zcnes and for incidence and degree of motor blockade among the 2 groups. VAS pain scores were 0.10 and 0.15 for Grcup A and B, respectively, while corresponding VAS satiafaCtiCn scores were 9.9 and 10 (P=NS).

Data suggest that although there was a tendency for the levels of sensory denervation tc extend mere cephalad in Group A than in Group B, this did not reach statistical significance. Data also indicate that distinct zones of differential sensory blockade develop during continuous infusion of very dilute local anesthetic plus FENT. Furthermore, although Group A patients received almost twice es much BUP (63.8 mg) as Group B (32.5 mg) (P<O.O5), the incidence of motor blockade wee similar, as were VAS pain, VAS satisfaction, and incidence of pruritus. Thus, 0.0625% BUP + PENT is as effective as 0.125% BUP + FENT, while total dose of local anesthetic is eignificantly lower. References 1. Anesthesiology 68:754-159, 1988

Group A (n=ZO) Group B (n=26) Motor blockade 3.7fO.l 3.8f0.4 Total BUP (rag) 63.0f6.7 32.5i3.4 Infusion rate 15.2f3.1 15.3t3.2 Width of ScSee

PP-TE 1.oi1.2* 0.5f1.2 LT-PP 1.4f2.0* 1.5f2.5* LT-TE 2.4f2.4= 2.0i2.2* VI-PP 3.1*0.4* 1.3f3.2* VI-TE 2.4f3.4* 1.a*3.3= LT-VI O.li3.8 0.3*2.9

All values are expressed as mean * SD. * PsO.05 when compared between 2 variables in each group.

101

-

.-

REGIONAL ANESTHESIA, CESAREAN SECTION, AND LABOR STATUS SION LESS COMMON IN LABORING WOMEN? .Clark. and Mark A. Brown, M.D.

University of Arkansas for Medical Sciences De artment of Anesthesiolo 4311 W Markham - Slot 5 @ Little Rock, Arkansas 72205

durin MEhODS: Informauon was

labor may also play a part.

our institution in calendar year f athered on all patients under oing cesarean section at 989. Type of anesthesia u t&d , labor status, whether

membranes were ruptured-or not, age,. weight, height, presence of hypotension, interval between administration of regtonal anesthesia to delivery, amount of intravenous fluid administered, etc. were recorded. RESULTS: Three hundred thuty-three patients delivered under regional anesthesia (249 e idural, infus eB

84 spinal). All atients had at least 2000 ml balanced salt solution before delivery and le K uterine displacement was

patients with epidural anesthesia, 75 were not m labor an 8” t-formed. Of the 249

z%;f ~{_;;~-$~tt+~uents we “‘p” 174 were in labor. Thirty-

tensive (52%), versus 36 who did not

(68%) who id not. laboring pattents 32%) became hypotensive, versus 119

Regardin the labor and 58 were in labor. 0 $ tl the

auents receiving spmal anesthesia, 26 were not in 6 non-laboring pauents, 18 became hypotensive

(69%) and 8 did not (31%). Of the 58 laborin became h tensive (3 1%) and 40 did not (69 4

patients receiving spinal anesthesia, 18 ). Thus, patients receiving spinal

anesthesta or cesarean section were more likely to become hypotensive than those Y? receiving e idural anesthesia. Laboring were less h % ely to become hypotensive z

atients in both the spmal and e idural ou s an those not m labor $=.OOl$. Of K 1%

laboring patients receiving eptdural anesthesia, 146 had ruptur membranes. Of the 58 laborin CONCLU&N: Lab

atients receiving spinal anesthesia, 37 had ruptured membranes. oring pattents are less likely to become hypotensive when

anesthesia for cesatean section than non-labonn patients. Since in atients were well hydrated, it does not seem that m a% equate hydration of

plays a major role. Most laboring patients have ruptured amniotic fluid when the come to section. Thus, it seems likely

that the large fluid-tilled uterus of the non-l a310. nng patients exerts significant pressure on the inferior vena cava after reaional block for cesarean section. desuite left uterine displacement, and contributes to &he greater incidence of hypotension. *We are

ursuing this concept as a possible cause. p?!&&CES:

Clark RB, et al: Prevention of spinal hypotension associated with cesarean

2. section. Anesthesiolo 45 67q, 1976. Antoine C, et al: Fe

d .:

14??55~ 1988 acttc acidosis with epidural anesthesia. Am J OB GYN

____. 3. Br&$ RV, et al: The incidence and neonatal effects of maternal h tension

durin 4. Craw ord JS: Principles and Practice of Obstetric Anaesthesia. 4th Ed., 1978, f

epidural anesthesia for cesarean section. Anesthesiology 67: y3” 82, 1987.

p. 216.

102

-

-

_.

-

_~

-

_

_

.-

A COMPARISON OF INTRATRECAL MORPHINE DOSES FOR THE MANAGEMRNT OP POST CESARRAN SECTION PAIN

V. Cases-Cristobal,M.D., W. E. Ackerman, M.D. M. Juneja, M.D. P. J. Andrews M.B.. FFARCS, R. Urella, M.D., C. Cases-Bernado, M.D., B. Rigor, M:D. Department of Anesthesiology, University of Santo Thomas Manila, Philippines and the University of Louisville College of Medicine Louisville, Kentucky 40202

Introduction. Intrathecal morphine (IMS) < 0.25 mg has been reported to be effective for section pain.'

the management of post cesarean This investigation compared IMS doses and

side effects for the management of post cesarean section pain.

Methods. Following IRB approval and patient informed consent 60 ASA I patients who requested spinal anesthesia for cesarean section were randomly assigned to one of 4 groups: I, 0.2 mg of preservative free MS/.06 ml NaCl; II 0.4 mg MS/.04 ml NaCl; III 0.6 mg MS/O.2 ml NaCl, and IV 0.8 mg NaCl. All study solutions were administered in a double blinded fashion immediately prior to the administration of 12 mg of spinal tetracaine placed at L3 or L4 through a 25 gauge Quincke spinal needle. Intraoperatively, the blood pressure, pulse and respiratory rate were monitored every 5 min. Postoperative respiratory rate monitoring was done hourly for 24 hours by ward nurses who were blinded to the IMS administered. A Verbal Assessment Pain Score (VAS), (O-10) was used to assess analgesia every 60 min while the patient was awake and every 4 hours during vital sign checks if the patient was asleep until the patient reported any pain at which time the study ended. No patient was included in the study if they had a history of drug abuse. Statistical analysis consisted of ANOVA, the Tukey test and X2 contingency where applicable.

Results. There were no differences between the groups with respect to demographics, duration of surgery, side effects or uterine eventration. The duration of analgesia was as follows: Group I 4.4 (O.g)hrs, III 31.6 (18.4)*hrs,

Group II 9.8 (3.5)hrs, Group and Group IV 48.2 (23.2)'hrs. No patient

in any group had a respiratory rate ~10 breaths/min.

Discussion. The dose of intrathecal morphine necessary to provide consistent analgesia was less than that reported by Abboud et al' to be effective. This study was done in a Philippine population. Further study is being conducted to determine if pharmacogenetic differences exist between ethnic groups.

Reference. Abboud TK, Dror A, Mosaad P, et al: Anesth Analg 67:137-43, 1988 l P<O.O5

103

-

-

__

.-

-

_.

_-.

,-

-

Title: INCIDENCE OF POST-DURAL PUNCTURE HEADACHE IN CESAREAN SECTION PATIENTS

Aandoaired comparison of 24-6A Sprotte vs 25-Sa Quincke needle

Authors: Devcic A, flaitra-D’Cruie All, Sprung J, Pate1 SN,

Kettler RE, Abendroth SA

Affiliation: The Departaent of Anesthesiology, l4edical College of

Wisconsin and *St. Joseph’s Hospital, Hilwaukee, WI

Introduction: Post-dural puncture headache (FDPH) is a coanon corplication of spinal anesthesia, especially in

the obstetrical population. Recent studies, are advocating Sprotte needles as a aeans to lower the incidence of

this important complication. Soae of these studies included relatively small numbers of patients and others

studied patients of different age and gender or coabined obstetrical with non-obstetrical population. Datta et

al have suggested that intrathecal fentanyl say reduce the incidence of PDPH. This prospective, randoaised study

coapared the incidence of PDPH with two spinal needles uhich are very similar in size, but different in design:

Sprotte (24-6a, non cutting point1 (S) vs. Quincke (ZS-Ga, diamond, cutting tip) (PI. In addition, we examined

proposed protective role of fentanyl, when added to local anesthetic solution for spinal anesthesia.

Method<: Institutional approval for the study and informed patient’s consent Has obtained. One hundred and

eishtvsir ASA l-2 patients scheduled for emergency or eiective C-sections, Mere randonly assigned to receive

spinal anesthetic with one of two needles (S:90, Q:96). In addition, half of the patients in each needle group

received 2Oug of Fentanyl PIUS 0.75: Rupivacaine and the other half plain 0.75X Supivacaine. All patients were

prehydrated with 1000-1500 lactated ringers solution. A aidline lumbar approach Has used, with bevel parallel

to dural fibers. Patients Here evaluated at the time of discharge, and calied three weeks later. Patients with

coaplaints of headache Yere questioned in detail by an investigator, who was not aware of the needle type and

medication used for spinal anesthesia. Only headaches (HAI with postural characteristics nere accepted as PDPH.

Severity of HA was gradej I (PRH oral analgesics only), II (scheduled analgesics, i.v. fluids, bedrest, abdominal

binders) and III (epidural blood patch). Unpaired t-test and X2 Here used to conpare data between groups with

~(0.0s deened significant.

Results: Population, age and weight were nearly equal in both groups. A total of 10 PDPH occurred. A lower

number of headaches Mere found in S group (1 rild and 2 severe, for a total of 1) than in Q group (2 aild, 3

moderate and 2 severe, for a total of 7). The difference was not found to be significant (3.5: vs. :.j:,

X2;0.05). A total of ?I patients received fentanyl and 7 had PDPH (7.7X), as opposed to 3 PDPH in the group that

did not get fentanyl (3.2:) (not a significant difference).

Conclusion: Ue found the S needle to be easy to use and a valuable teaching tool (because of the distinct feel

that the needle provides during the performance of the spinal), but in a carefully controlled study of uniform

patient population, the incidence of PDPH was not significantly lowered in the S group as compared to the Q group.

The addition of fentanyl to local anesthetic did not lover the incidence of PDPH.

References: l! Rrooae JA, Schapiro Htl, A randomized comparison of Sprotte versus Puincke tip needles in

outpatients. Anesthesiology 7S:AllO4, l??l.

21 Johnson HD, Hertuig L, Vehring PH, Datta S: Intrathecal fentanyl say reduce the incidence of

spinal headache. Anesthesiology 71:A911, 1989.

Table 1

Patients (n)

SPROTTE QUINCKE

90 96

Age (yr) IKfSEH)

Weight (kg) (XiSEtl)

28.9,0.55

78.2il.7 28.3tl.O

81.61_1.8

PDPH 3 (3.3:) 7 (7.3:)

- Grade I 1 2

- Grade II 3

- Grade III 2 2

104

-

-.

lntrathecal Narcotics Cause Hypotension During Labor

.- Authors:

Affiliation:

Ducev JP’, Knape KGI. Taibot J’

Anesthesiology Service, Brooke Army Medical Center’; Department of Anesthesiology, University of Texas Health Science CenterX; San Antonio, Texas 78284-7838

INTRODUCTION: The combination of intrathecal morphine and fentanyl is well known to be effective for labor analgesia, yet related hypotension has not been reported.’ At this instiiution, though, a drop in blood pressure was often noted immediately after dosing. The incidence and significance needed to be determined.

METHODS: We retrospectively reviewed the effects of narcotics administered intrathecaiiy on the maternal blood pressure response, fetal heart rate response, and the frequency of contractions in 100 consecutive parturlents. lntrathecal morphine 0.25 mg plus fentanyl 25 mcg (undiluted. total volume 0.75mi) was administered to women in the first stage of labor, with cervical dilatation ( 4 cm. All women were prehvdmted wtth ot least 500mls of a balanced salt solution. All blood pressures were recorded in the lateral decubitus position.

RESULTS: Systolic, diastolic and mean blood pressures decreased 25 + 1, 18 + 1 and 20 + 1 mmHg. respectively. from laboring values. and 12.6 + 1.4. 13.1 + 1.3 and 13 + 1.2 mmHg. respectively. from prelabor. third trimester levels. The systolic pressure decreased to less than 90 mmHg in 14 patients, and to less than SO mmHg in 3 patients. The systolic. diastolic and mean blood pressures decreased more than 20% in 46, 69 and 63 patients, respectively, from laboring levels. and in 21. 56 and 41 patients, respectively. compared wtth preiabor. third trimester levels. 23 patients received ephedrine for blood pressure support. Onset of BP drop was 12 + 1 min. BP nadir was at 20 + 1 min. Values are mean + SEM.

Y of pts with drop in BP compared with

SBP decrease z 20% DBP decrease > 20% MBP decrease > 20%

Prelabor BP Laboring BP

: % 41 63

lntrathecai narcotics had no effect on fetal heart rate: specifically. no deceleration pattern was attributed to hypotenslon, nor was cesarean section ever required for fetal distress attributable to intrathecal narcotics. The frequency of contractions was not affected.

DISCUSSION: The mechanism of hypotenslon due to intrathecal narcotics is unclear, though may involve attenuation of an opioidergic. spinally-mediated pressor response.2 Other factors include relative hypovolemla in the ‘starved’ parturlent and an indirect decrease in sympathetic tone due to rapid onset of pain relief. Further prospective study is needed.

CONCLUSION: lntrathecai morphine plus fentanyl was associated with frequent and significant hypotension in spite of prehydration. and often required ephedrine. Therefore, all patients receiving intrathecal narcotics should be prehydrated and closely monitored for a decrease in BP, as per the routine used for inttiating epidurals using local anesthetics.

REFERENCES: 1) Leighton BL. DeSimone CA. Norris MC, Ben-David 8: Anesth Analg 69122-125. 1989 2) Williams CA: Cardiovasc Res 23:191-199, 1989

105

TITLE: Cerebrospinal Fluid (CSF) Pharmacodynamics and a Possible Cholinergic Mechanism of Epidural Clonidiie Analgesia in Humans

AUTHOR:

AFFILIATION:

James C. Eisenach, M.D.*

Department of Anesthesia, Wake Forest University Medical Center, Winston-Salem, North Carolina

Introduction: This study sought to define clonidine CSF pharmacokinetics in humans in order to address 3 questions: Does epidural clonidine produce analgesia by a regional spinal mechanism? Is this analgesia mediated by acetylcholine (ACh) release? What are the CSF pharmacokinetics for design of future infusion protocols?

Methods After written informed consent and IRB approval, 10 volunteers were studied. Radial arterial, peripheral intravenous, lumbar epidural, and lumbar intrathecal catheters were inserted under local anesthesia. Volunteers received 700 B clonidine epidurally, then CSF and plasma were sampled at specific intervals for 24 hrs for clonidine analysis and CSF ACh analysis. At specified intervals pain visual analog score (VAS) after foot, then hand immersion in iced water was obtained, and blood sampled for catecholamine analysis and finger and toe photoplethysmography (PPG) as measures of sympathetic nervous system (SNS) activation. VAS sedation and arterial blood gas tensions were also obtained. Data analysis was by ANOVA and by Pearson correlation.

a Clonidine produced sedation lasting 4 hrs, diminution in VAS pain report which was greater in the foot than the hand (P < O.OOl), and minor increases ( < 3 mm Hg) in arterial Pco,. Despite differences in pain report, PPG evidence of SNS activation during pain testing was diminished to a similar degree in both hand and foot. Clonidine was rapidly absorbed into CSF, with peak concentrations >500 ng/ml 15 min after injection, and was eliminated with a half-life of 0.5-2.5 hrs. Correlation of CSF clonidine to VAS pain in the foot revealed a linear effect, with maximal reduction in pain at concentrations > 140 ng/ml. CSF ACh increased from undetectable levels to 110 k 20 pmol/ml 60 min after epidural clonidine injection.

Discussion: Regional analgesia and tight correlation of analgesic effect with CSF but not plasma clonidine concentration argue strongly for a spinal effect of epidural clonidine in humans. Diminished SNS activation after either hand or foot testing is consistent with rapid clonidine absorption and sympatholysis by a central mechanism. Pharmacokinetic parameters in these volunteers agree well with duration of analgesia after clonidine bolus and analgesic intensity of different infusion regimens in postoperative patients. Increased CSF ACh after clonidine agrees with anatomical, functional, and neurophysiologic studies in animals suggesting a cholinergic link in spinal c+-agonist analgesia. This provides the rationale for development of drug combinations to enhance epidural clonidine analgesia. Supported in part by grant GM35523 from the National Institutes of Health.

106

-

.-

-

.._~

_

-

Title: THE USE OF PCA NALBUPHINE VS. MORPHINE IN CESAREAN DELIVERY PATIENTS FOLLOWING INTRATHECAL DIJRAMORPH

Authors: Gina M. Fedel M.D,, Gordon L. Mandell MD, Theodore Riley M.P.H.

Affiliation: Department of Anesthesiology, Magee-Womens Hospital, Pittsburgh, PA 15213.

INTRODUCTXON Despite providing effective analgesia, intrathecal Duramorph (ID) is associated with side effects, includiig respiratory depression, pruritis, and nausea and vomiting. In addition, many patients receiving ID require additional narcotics for postoperative pain relief. PCA Nalbuphine is a safe and effective postoperative analgesic.’ The purpose of this study is to test the effectiveness of IV PCA Nalbuphine in augmenting ID while decreasing side effects.

THODS: Sixty patturients will be studied. Human Experimentation Committee approval and informed consent were obtained from ASA I and II parturients for elective cesarean delivery with spinal anesthesia (0.75% bupivacaine with 0.25 mg ID). The parturients were randomly assigned to receive either PCA morphine (MS) or nalbuphine postoperatively in a double-blind fashion. Upon arrival in the recovery room, and for twenty-four hours following ID administration, patients evaluated their pain, pain relief, and incidence of side effects, using a set of six visual analog scales. Demographic characteristics of all patients were recorded. The groups were also compared with regard to PCA doses delivered and PCA doses demanded. The groups were compared using the T-test, analysis of variance repeated measures, and chi-square @ < .05 was considered significant).

RESULTS: A total of 20 parturients have been studied. Parturients in the PCA Nalbuphine group (n=lO) exhibited approximately three times the number of PCA demands (14.2 versus 4.4 versus the MS group, p < .04), and received twice as many PCA deliveries (39.7 versus 19.9 p < .Ol). The PCA Nalbuphine group also reported slightly higher pain scores and less satisfaction with pain relief than the PCA MS group, although these values did not achieve statistical significance @ > 0.364 and p > 0.665, respectively). There were no statistically significant differences in the incidence of side effects (itching, nausea or sleepiness) between the two groups.

DISCUSSION: These findings suggest that when compared with PCA MS, PCA Nalbuphine is less effective in augmenting ID and does not decrease the incidence of side effects. The pain scores were higher for the PCA Nalbuphine group, yet the incidence of side effects were similar between the two groups.

REFERENCES

1. Kay B, Krishman A: On demand nalbuphine for postop relief. Acts Anesthesiologica Belgica 37:33-37, 1986.

107

-

.-

m Comparison of Anesthesia Techniques for In-Vitro Fertilization

__ Authors: Fragneto R, Bader AM, Manica V, Gilbertson L, Datta S

Affiliation: Brigham and Women’s Hospital. Harvard Medical School, Boston, MA

Introduction: While in-vitro fertilization procedures are becoming increasingly common, little information exists about the benefits or disadvantages of different anesthetic techniques. This study attempts to compare two types of local anesthetic agents used in spinal anesthesia, with particular attention to length of stay in the recovery room.

Methods: Approval was obtained from the hospital’s Human Subjects Committee and 56 patients scheduled for in-vitro fertilization egg retrieval under spinal anesthesia were studied. Patients were randomized in a double-blind fashion to receive hyperbaric solutions containing 10 micrograms of fentanyl with 60 mg of either 5% or 1.5% lidocaine. Sensory level and motor block using Bromage Scale were measured at intervals of 1,2.3,4.5,10, 15, 30, and 45 minutes after spinal injection; while in the operating room. Duration of procedure, side effects, ephedrine dosage, intravenous supplementation, time from spinal placement to ambulation, voiding, and discharge were compared between the two groups. Data were compared using Student’s t test, Chi-square, and Mann-Whitney analysis where appropriate.

PeSUltS: Patient demographics, procedure duration, ephedrine dose, and intravenous supplementation requirements did not differ between the two groups. Patients receiving 5% lidocaine had significantly more motor block at 1 minute; there were no other significant differences in sensory level and motor block at the times measured. Patients receiving 1.5% lidocaine had significantly shorter times to ambulation and voiding, and were discharged sooner than patients in the 5% lidocaine group.

Discussion: When spinal anesthesia is used for egg retrieval procedures, the use of 1.5% lidocaine appears to offer the benefit of shorter recovery room stay. TABLE ONE

1.5% LIDOCAINE 5% LIDOCAINE TIME TO AMBULATION (MIN) 141+1-21 162+1-29 PcO.05 TIME TO VOID (MIN) 147+/-21 i 74+/-28 ~~0.05 TIME TO DISCHARGE (MIN) i 70+1-38 201 +I-41 P<O.O5

TITLE: Comparison of Intrathecal Sufentanil, Sufentanil/Bpinephrine, and Sufentanil/Morphine for Labor Analgesia.

AUTHORS: WM Grieco. M.D., MC Norris, M.D., BL Leighton, M.D., VA Arkoosh, M.D., HJ Huffnagle, D.O., JB Honet, M.D., D Costello, M.D.

AFFILIATION: Department of Anesthesia, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107

Introduction: Imath opioids offer an altemative to epidural local anesthetics for labor

analgesiaHowevu;theyhaveafiniredurationofaction.l2Inthisstudy,weattemptedtoprolong

the dutation of subatachnoid sufentanil labor analgesia by adding epinephrine or morphine. Methods Forty five healthy term primagravidae with cetvical dilatation < 5 cm consented ~participateinthisIRBapprovedstudy.Weidentifiedthelumbarepiduralspacewithan18gauge Hustead needle. We then inserted a 24 gauge x 120 mm Spmtte@ needle thmugh the epidural needle until ftee flow of CSF was obtained and injected, as determined by a table of random numbers, either sufentanill0 pg; sufentanill0 pg plus epinephtine 0.2 mg; or sufentanil10 l.tg plus morphine 0.25 mg. After removing the spinal needle, an epidtnal catheter was inserted into thelumbarepiduralspace.Atbaselineandeveryfiveminutesfor30minutesaftertheinitialopioid injecdonthepatientsratedtheirpain,nausea,andptutituson 10cmhorizontalvisualanalogscales (VAS). The women continued to rate these variables every 30 minutes until they requested additional analgesia when they received 10 mL of 0.25% bupivacaine in incremental doses via theepiduralcatheter.Thepatientsthencontinuedtoratetheabovevariablesev~30minutesuntil they again requested additional analgesia. We used ANOVA to evaluate demographic data and Km&al-Wallis to evaluate pain, nausea, and pruritus VAS and duration of action data Results: The 3 patient groups did not differ in age, baselinepain,nausea,andpmrirus 0 0

scores, time to delivery, Apgar 200 scores, methodof delivery, dura- 0 0

tion of first or second stages of = tso labor, or incidence of post duraJ g

puncture headache (0%). Addi- ; tion of morphine (p =0.014), but g loo not epinephtine (p = 0.088). sig- niticantlyprolongedtheduration ss of sufentanil analgesia (figure). Them were no differences in the a duration of subsequent epidural surentana Sufentanil- Sufentanii-

bupivacaine.Themorphinegmup Epinephrine MOrpbilW

l p -z 0.05 Vs. Sufentanil experienced significantly more nausea and pruritus throughout the study period.

Diiion: Morphine 0.25 mg, but not epinephtine 0.2 mg, significantly prolongs innathecal sufentanil labor analgesia. In return, this dose of morphine increases the incidence and severity of pruritus and nausea. The addition of morphine had no significant effect on the duration of subsequent epidural bupivacaine. References: 1. Anesth Analg 1989;69:122., 2. Anesthesiology 1991;74:711.

-

,~~

-

Title:

Author:

INCIDENCE OF POST-DDRAL PDNCTURR HEADACHE AT WOHRN'S HOSPITAL: 16 NORTR STUDY

m Abboud, & J 2hu, RD, E Peres Da Silva, ND, N Donovan, ND

Affiliation: Department of Anesthesiology, Los Angeles County+ university of Southern California Medical Center, Los Angeles, California 90033

Introduction: Post-dural puncture headache (PDPH) is a common complication of spinal anesthesia or unintentional dural puncture. The shape and the gauge of the needle have been shown to influence the incidence of headache. The present study was undertaken to determine the incidence of PDPH during a 16 month period in the obstetrical patient. Method: After approval of the institutional review board and informed consents, 1078 patients who received spinal anesthesia for cesarean section or had unintentional wet tap from June, 1989 to September, 1991 were studied. Different size and type needles were used including Quincke point needles, Whitacre and Sprotte needles. When Quincke needles were used, the bevel of the needle was inserted parallel to the longitudinal dural fibers. Blocks were performed by residents in training. Postoperative visits were made by the research staff throughout the patient's hospital stay to evaluate the incidence of PDPH. Data were analyzed using the chi-square analyses. A P value of CO.05 was considered statistically significant. Results are presented in the Table and they indicate that 22, 25 and 26 Quincke needles are associated with a higher incidence of PDPH compared to Quincke 27, Whitacre or the Sprotte needles with no significant differences between the Sprotte and the Whitacre needles. Discussion: 22 G Whitacre needles or 24 G Sprotte needles are technically easier to use than 27 G Quincke needle and they provide rapid CSF return. Whitacre is currently used in our institution since it is more cost effective, more rigid than the Sprotte and has a smaller orifice and hence is less likely to result in inadequate block if the orifice is partially in the subarachnoid space. Further studies are under way to evaluate 25 G. Whitacre needle in the obstetrical patient.

Table

Number of Patients

PDPH (%)

18 G. Tuohy 88 43 (43%) * 22 G. Quincke 227 43 (18.9%) * 25 G. Quincke 245 42 (17.1%) * 26 G. Quincke 164 24 (14.6%) * 22 G. Whitacre 267 25 (9.4%) ** 27 G. Quincke 36 0 (0%) 24 G. Sprotte 51 1 (2%)

* P CO.01 compared to the last 3 groups. ** P CO.05 compared to 27 G group.

110