Anest gen nel cesareo

Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)

1)Mortalità materna 2)Anest generale nel

cesareo urgente e non

Claudio MelloniDirettore U.O.Anestesia e Rianimazione

Ospedale di Faenza


Allan C. Barnes, M.D., Professor of Obstetrics and Gynecology, Johns Hopkins University, circa 1965.

The removal of a brain tumor in an elderly patient calls for a surgeon with two assistants, scrub nurse and two circulating nurses, and an anesthetist and an assistant. The patient's prognosis is about 18 months and the hospital investment is tremendous. In contrast, the birth of a new baby at 4:00 a.m. is more often attended by one physician, no scrub nurse, one circulating nurse and inadequate or haphazard anesthesia coverage. As a profession, we seem to be committed to the fallacy that to be interesting, one has to be an adult, fully developed, and preferably degenerating.


Ostetricia ad alto rischio:posto per la regionale…..

Una buona scelta anestetica puo’ migliorare la situazione:» epid * PIH/preeclampsia

Una cattiva scelta anestetica puo’ peggiorare la situazione:»GA & intubaz. Difficile:l’autostrada per il

disastro….


WHO

Mortalità materna: 5-10/100.000 gravidanze paesi

sviluppati 500-1000 /100.000 paesi sottosviluppati

500.000 morti materne per anno


Betran et al National estimates for maternal mortality:an analysis based on WHO Systematic Review of maternal mortality ane morbidity .BMC Public Health 2005,5.131


Dati WHO 1990


Mortalità materna in Italia


Mortalità materna in England e Wales 1847-1984


«Underreporting » Francia 56%

– Bouvier-Colle.J.Int.J.Epidemiol 1991

Olanda 26%– Schuitemaker Obstet.Gynecol 1997

Austria 38%– Karimian Acta Obstet Gynecol Scand 2002

Finlandia 60%– Gissler Acta Obstet Gynecol Scand 1997


Ministero della Salute

La mortalità materna è stata inclusa negli eventi sentinella per lo studio e la riduzione del rischio clinico


Hawkins JL,Koonin LM,Palmer SK,Gibbs CP.Anesthesia related deaths during obstetric delivery in the United States(Anesthesiology 1997;86:277-84).

Morti materne in USA 1979-1990 cause Relazione con l’anestesia Tipo di procedura ostetrica Condizioni materne concomitanti


Hawkins et al.Anesthesia related deaths during obstetric delivery in the United States(Anesthesiology 1997;86:277-84).

02468

1012141618

%

79-81 82-84 85-87 88-90

num.tot=129

GAREGignotasedazione


Hawkins JL,Koonin LM,Palmer SK,Gibbs CP.Anesthesia related deaths during obstetric delivery in the United States(Anesthesiology 1997;86:277-84).

C S 82% parto vag 5% ignoto 13%

Mortalità ostetric a


C/S Mortality (from Hawkins…)

asp iraz3 3 %

p rob l d i in d u z /in tu b az2 2 %

ven tilaz in ad eg1 5 %

in su ff resp3 %

arres to ca rd d u ran te an es t2 2 %

AG :52% del totale

Oppioidi o sedativi parent

3%

ep id u ra le7 0 %

sp in a le3 0 %

Regionale25%


Number of deaths during cesarean sectionNumber of deaths during cesarean sectionUSA 1979-1990(Hawkins et al.Anesthesiology 86;280:1997)USA 1979-1990(Hawkins et al.Anesthesiology 86;280:1997)

1979-19841979-19841985-19901985-1990

GAGA 3333 3232

REGREG 1919 99


Fatality rates during cesareansection


per million of Ga or REGper million of Ga or REG

1979-19841979-19841985-19901985-1990

G.A.G.A. 2020 32.332.3

REGREG 8.68.6 1.91.9


Causes of anesthesia related deathsCauses of anesthesia related deathsUSA 1979-1990(Hawkins et al.Anesthesiology 86;280:1997)USA 1979-1990(Hawkins et al.Anesthesiology 86;280:1997)

AG(67)AG(67)Reg(33)Reg(33)sedaz(4)sedaz(4)ignota(25)ignota(25)%% NN

Probl.vie aereeProbl.vie aeree 7373 -- 7575 4040 4949 6262

arresto card.intraoparresto card.intraop2222 66 -- 5252 2323 3030

tox da ALtox da AL 5151-- -- 1313 1717

spi/pd altaspi/pd alta 3636 -- -- 99 1212

iperdosaggioiperdosaggio -- 2525 -- 11 11

anafilassianafilassi -- -- 44 11 11

ignotaignota 55 66 -- 44 55 66

%% 100100 100100100100 100100100100129129


Incidenza della mortalità materna da CDC USA: GA vs reg.

GA 2.3 * > reg (1979—1984)

GA 16.7 * > reg ( 1985—1990).


Mortalità materna attribuita all’anestesia

4.3/milione di nati vivi( 1979—1981)

1.7/ milione di nati vivi (1988—1990).

8.7/milione di nati vivi( 1979—1981)

1.7/ milione di nati vivi (1988—1990).

CDC USA CEMDEW


Report on Confidential enquiries into maternal deaths in England and Wales 1970-1999

0

5

10

15

20

25

30

35

1970-72

73-75

76-78

79-81

82-84

85-87

88-90

91-93

94-96

97-99

Frequenza per milione di gravid.stimate

emb.polm

ipertens

anest

emb.fluido amniotico

aborto

gravid.ectopica

emorragia

sepsi

rottura utero

altre cause dirette

Entrata in vigore della nuova classificazione


Mortalità ostetrica attribuita all’anestesia 1970-1999 CEMDUK

0

2

4

6

8

10

12

14

1970-72

73-75

76-78

79-81

82-84

85-87

88-90

91-93

94-96

97-99


Effetti ipotensivi dell’ossitocina


Fatti salienti da CDC USA: la mortalità anestetica legata all’anestesia;cause e differenze fra AG e reg.

Il numero assoluto di morti materne da AG è rimasto stabile negli anni 1979-1990.

I problemi di vie aeree sono la causa principale di mortalità da AG,mentre il numero assoluto di morti legate alla anest.reg. è in calo dal 1984,equamente divise fra tossicità da AL e anestesia spinale/perid alta.

Tuttavia sono diminuite le morti da tossicità da AL da quando Food and Drug Administration ha tolto l’approvazione per la bupivacaina 0.75% in ostetricia.


Complications of AG for C/S: CDC USA

20.0/milione GA ( 1979—1984)

32.3 morti/milione (1985—1990)


CS: mortalità per anest reg CDC USA

8.6 /milioni di anest reg ( 1979—1984)

1.9 /milione ( 1985—1990).


Perché è possibile che ci sia ancora una mortalità + alta con AG?

Perché negli ultimi anni non si fanno + AG!!!

Paz + anziane Paz + ammalate Classi socioeconomiche meno

abbienti….immigrati…..


Instaurazione precoce della analgesia(P.d.) in

travaglio In generale, eviterà la GA. Permette la precoce scoperta di un catetere pd

“sospetto”,……..

non tutte le anest reg sono in grado di portare a termine il parto operativo;» distress non anticipato intraop(dolore,emorragia massiva

intraop con instabilità emodinamica….)


GA:pro & contro

veloce Alta % successo Pieno controllo Rilasc.uterino

(alog..) Meno ipotens Protez delle vie

aeree (ma nel mentre….)

Probl. Con vie aeree Aspirazione Ipertens durante

laringoscopia e intubaz Depressione cardiaca Depressione resp Depressione neonatale “Awareness”


Anestesia regionale;pro & contro

cosciente Psicologico… Legame

materno/fetale: la madre si fa carico

immediatamente del neonato…

No intubazione Minor rischio di inalaz Analgesia postop Soddisfazione

materna

Tecnicamente + difficile

Consumo di tempo ipotensione


Indicazioni per AG (QCCH,Crowhurst 2001)

cord prolapsesev.fetal distressmaternal requestfailed regReg contraindicated


Richiesta materna per AG

Ansietà Pregressa esperienza:

cattiva(con reg)» buona(con GA)» dorsalgia

» Quando non vengono visitate nella clinica preop o prenaest…….


Anesthesia for emergency C/S

Morgan et al.BJA 1990;97:420-24 “need for emergency C/S anticipated in

87% (380 cases).Early establishment of epidural analgesia in labour allowed extension to adequate anaesthesia in 70%”

Crowhurst(ESOA 2001);99% extension


Domande sull’emergenza

Epid in sede:quanto ci vuole dal rifornimento ad un blocco adeg.per C/S?

Intervallo decisione-parto Rischio fetale:quanto da AG e quanto da

reg? Strategie che beneficino il feto……..


CESDI:Confidential Enquiry into Stillbirths and deaths in infancy,7th report,2000

Composizione:» OB anesthesia focus group» 2 ob anesthesiologists» 2 obstetricians

873 perinatal deaths;25(2,8%)anesth.contributing factors identified:» maternal anaphylaxis1,» maternal bronchospasm and hypoxia 1,» failed/difficult oti 2» Delay with personnel 11» Delay in administering anesth 10


Ottimizzazione della fisiologia materno fertale

1)Materna: 1)trasporto di O2» 2)ventilazione » 3)circolazione» 4)flusso ematico uteroplacentare

5)flusso ematico ombelicale(fetal)

1-4 possono essere ottimizzati


Listato dei punti di interesse

Profilassi ab ingestis Posizionamento Vena di calibro adeguato Monitoraggio Preossigenazione Induzione Manovra di Sellick IOT Mantenim :preparto Mantenim post parto estubaz


Valutazione preanestetica Vie aeree IOT:anestesisti e ostetrici…..

Gaiser RR, McGonigal ET, Litts P, et al: Obstetricians’ ability to assess the airway. Obstet Gynecol 1999; 93(5 Pt 1):648–652

funzionalità cardiovascolare precarico? funzionalità respiratoria allergie stratificazione del rischio


Valutazione vie aeree:Mallampati,Cormack etc


Test di protrusione mandibolare


Definito il rischio: Raduna aiuto prepara carrello intubazione difficile procedi alla analgesia in travaglio(pd cont) segui il parto visita regolare dell’area travaglio e del reparto di

ostetricia; (Morgan BM, Magni V, Goroszeniuk T: Anaesthesia for emergency caesarean section. Br J Obstet Gynecol 1990;97:420 & Morgan M: Anaesthetic contribution to maternal mortality. Br J Anaesth 1987;59:842.)

PREVENZIONE DELLE EMERGENZE NELL 87% DEI CASI


Ricorso non necessario alla AG

Inadeguata educazione della paziente abitudini chirurgiche chiamata tardiva controindicazioni sorpassate:

» preeclampsia» placenta praevia» febbre» mal.cardiache


Prevenzione delle C/S di

urgenza(Morgan,Brit J Obstet Gynecol 1990;97:420)

visite preop congiunte 3 volte al dì analgesia peridurale raccomandata per

tutte le madri a rischio di C/S comunicazione continua fra reparto di

ostetricia e anestesia …risoluzione dei problemi

organizzativi…...


Indicazioni per GA in OBS

Personale di anest con scarsa esperienza in reg Rifiuto della reg da parte della paz Paz non cooperante Tutti i casi di controindicaz alla reg:

» Infez localizzata(dorso) vs generalizzata (sepsis)….

» Coagulopatia: emergenza: distress fetale,placenta praevia, emorragia materna,

manovre ostetriche urgenti ……. ipovolemia…. Certe cardiopatie che non possono tollerare ipotens:CO fisso,per

es,stenosi aortica severa,Eisenmenger


Parekh N,Husaini SWU,Russell IFCaesarean section for placenta praevia:a retrospective study

of anesthetic management.Br.J.Anaesth.

2000;84:723-30. All anesth from 1 genn 1984 to 31/12/1998. 350 cases of plac previa:

» 60% Reg / 40% AG» plc accreta;7 cases; 4 REG , 3 AG:but 2 reg convert.to

AG…5 hysterect.» PA control during haemorrhage not a problem» RA assoc.with less blood loss» “This retropective study do not support the often quoted

motto that plac.praevia calls for AG….”.


Svantaggi della AG Paz addormentata e inconscia:legame materno neonatale più

tardivo… Marito meno probabile sia presente in sala op Depressione fetale da farmaci Risposta da stress all’IOT Aum morbilità postop Modificaz cardiovasc all’intubaz Pericolo di inalazione (intubaz & estubaz…) Intubaz difficile Dati di mortalità;CEMDUK,USA,ecc.


AG:tecnica :I Premed;antiacidi /H2 bloccanti/citrato di sodio LUD:

» Manuale,inclinazione del leto,cuneo sotto anca dx…. ID/ UI-D intervalli + brevi possibile preO2 (precurarizzazione)???? induzione “cricoid pressure” Succi o curaro del giorno?


AG:tecnica:II IOT Controlla espansione polm,bilat. N20 50% + halog 0.6 Mac Dopo parto:ripeti ipnotico + analgesico;stop volatile Ossitocina 10-20 UI/lt,drip…:lentamente!!! Estubare solo se sveglia e cooperante,assicurandosi

della piena ripresa nm … Pianificare per la fallita intubazione


Posizione della paziente

Prevenire la compressione aorto-cavale seduta:+ facile per le obese laterale;meglio per le presentazioni

podaliche con membrane rotte


Posizione

LUD;spostamento uterino a sn LLT;tilt laterale del letto a sn Trendelemburg lieve?

» Implicazioni per rigurgito….. Posizione ottimale per IOT:”Sniffing

position” “orecchie sopra le spalle”


Monitoraggio

Appropriato per ogni sala op. di chirurgia addominale:NIBP(ogni 1-2 min);ECG;SaO2,etCO2,TV,Paw,RR,N2O,alog…..

disponibilità di infusori rapidi di liquidi caldi possibilità monitoraggio PA continua cruenta e PVC possibilità di CO continuo…. Continuazione del monitoraggio fetale durante induzione

dell’anestesia e la preparazione chirurgica dell’addome…….


Capnometria sidestream Ossigenazione e FiO2


Ossigenazione /

preossigenazione


Benumof JL Critical hemoglobin saturation will occur before return to an unparalyzed state following 1 mg/kg

intravenous succinylcholine.Anesthesiology 1997;87:979.


Tempo di apnea fino al raggiungimento di una SaO2 specifica in pazienti in AG con confronto tratto da un modello matematico


Frequenza di iot fallite

16 anni di esperienza del St James 5802 GA per C/S 0.4% di iot fallite;1/300 1984,1/250

1994.» , L.; Hawthorne Wilson, R.; Lyons, G.; Dresner,

M. Failed intubation revisited: 17-yr experience in a teaching maternity unit

» Br. J. Anaesth. 1996; 76:680-684.


Frequenza di iot fallite(Tsen et al,Int J.Obset Anesth. 1998;7:147)

0

2

4

6

8

10

12

14

16

%

1990 1991 1992 1993 1994 1995

iot fallite


Cause delle iot difficili

Variazioni anatomiche fattori organizzativi:

» inesperienza» urgenze fuori orario» “stat” mentalità» panico

0

10

20

30

40

50

60

70

80

90

%

elettive emergenza

Iot fallite e tipo di C/S(Hawthorn,BJA 1996

% AG

fallite


Il Mallampati varia durante il travaglio!!!

Farcon EL.,Kim MH,Marx GF. Changing Mallampati score during labour Canadian Journal of Anaesthesia. 41(1). 1994. 50-51.» Primigravuida sana» All’ingresso:Mallampati 1-2» A 8 cm di dilatazione:Mallampati 3-4(edema

dell’ipofaringe)» Immediato postpartum:Mall;3-4» 1 H postpartum:Mall 1-2.


Aumento delle iot difficili in ostetricia

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

%

score 3

chir genC/S (Pilk)C/S (Durban)ost (Carli)


Cause delle iot difficili

Variazioni anatomiche fattori organizzativi:

» inesperienza» urgenze fuori orario» “stat” mentalità» panico

0

10

20

30

40

50

60

70

80

90

%

elettive emergenza

Iot fallite e tipo di C/S(Hawthorn,BJA 1996

% AG

fallite


Manovra di Sellick



Wraight WJ, Chamney AR, Howells TH. The determination of an effective cricoid pressure.

Anaesthesia 1983; 38:461-466.

44 Newton= 4.5 kg


Brimacombe JR,Berry AM.Cricoid pressure .Can J Anaesth 1997 ; 44: 414-425

Purpose: Although cricoid pressure (CP) is a superficially simple and appropriate

mechanical method to protect the patient from regurgitation and gastric insufflation, in practice it is a complex manoeuvre which is difficult to perform optimally. The purpose of this review is to examine and evaluate studies on the application of (CP). It deals with anatomical and physiological considerations, techniques employed, safety and efficacy issues and the impact of CP on airway management with special mention of the laryngeal mask airway.

Source of material: Three medical databases (48 Hours, Medline, and Reference Manager Update) were searched for citations containing key words, subject headings and text entries on CP to October 1996.

Principle Findings: There have been no studies proving that CP is beneficial, yet there is evidence that it is often ineffective and that it may increase the risk of failed intubation and regurgitation. After evaluation of all available data, potential guidelines are suggested for optimal use of CP in routine and complex situations.

Conclusions: If CP is to remain standard practice during induction of anaesthesia, it must be shown to be safe and effective. Meanwhile, further understanding of its advantages and limitations, improved training in its use, and guidelines on optimal force and method of application should lead to better patient care.


Evidenza a vantaggio della manovra di SELLICK


Evidenza contraria alla manovra di SELLICK


Gruppi di pazienti a rischio da una manovra di Sellick inappropriata


Carrello per intubazione

In sala op. laringoscopi:manico normale,sottile ,corto lame curve,rette,Bizzarri,ecc Guedel,Copa LMA di vari calibri mandrino di gomma,con ventilazione set crico tiroidotomia:Patil,Ravussin,ecc fibroscopio…….. jet ventilation……...








Hawthorne L,Wilson, R.; Lyons, G.; Dresner, M. Failed intubation revisited: 17-yr experience in a

teaching maternity unit .Br. J. Anaesth. 1996; 76:680-684


Gataure PS,Hughes JA.The laryngeal mask airway in obstetrical anaesthesia.Report of Investigation. CAN J ANAESTH 1995 / 42: 2 / pp130-3

questionario sull’utilizzo della LMA in caso di difficile o fallita intubaz in ostetricia

240 consultant in anestesia UK 72% favorevoli 10% con esperienza personale 2,5% asseriscono che la LMA ha salvato la

paziente Opinione generale che debba essere usata prima

della cricotiroidotomia


LMA in ostetricia 1. McClune S, Regan M, Moore J. Laryngeal mask airway for caesarean section. Anaesthesia 1990;45:227–8 2. de Mello WF, Kocan M. Further options for obstetric anaesthesia. Br J Hosp Med 1989;42:426. 3. Storey J. The laryngeal mask for failed intubation at caesarean section. Anaesth Intensive Care 1992;20:118–9 4. Christian AS, McClune S, Moore JA. Failed obstetric intubation. Anaesthesia 1990;45:995. 5. Chadwick LS, Vohra A. Anaesthesia for emergency Caesarean section using the Brain laryngeal mask airway. Anaesthesia 1989;44:261–2. 6. Lim W, Wareham C. The laryngeal mask in failed intubation. Anaesthesia 1990;41:689–90. 7. Priscu V, Priscu L, Soroker D. Laryngeal mask for failed intubation in emergency Caesarean section. Can J Anaesth 1992;39:893. 8. Hasham FM, Andrews PJD, Juneja MM, Ackermann III WE. The laryngeal mask airway facilitates intubation at cesarean section: a case report

of difficult intubation. Int J Obstet Anesth 1993;2:181–2. 9. McFarlane C. Failed intubation in an obese obstetric patient and the laryngeal mask. Int J Obstet Anesth 1993;2:183–4. 10. Vanner RG. The laryngeal mask in the failed intubation drill. Int J Obstet Anesth 1995;4:191–2. 11. Brimacombe J. Emergency airway management in rural practice: use of the laryngeal mask airway. Australian J Rural Health 1995;3:10–9. 12. de Mello WF, Kocan M. The laryngeal mask in failed intubation. Anaesthesia 1990;41:689–90. 13. Godley M, Ramachandra AR. Use of LMA for awake intubation for Caesarean section. Can J Anaesth 1996;43:299–302. 14. de Mello WF, Restall J. Difficult intubation. Can J Anaesth 1990;37:486. 15. Davies JM, Weeks S, Crone LA. Failed intubation at caesarean section. Anaesth Intensive Care 1991;19:303. 16. Shung J, Avidan MS, Ing R, et al. Awake intubation of the difficult airway with the intubating laryngeal mask airway. Anaesthesia

1998;53:645–9. 17. Hawthorne L, Wilson R, Lyons G, Dresner M. Failed intubation revisited: 17-yr experience in a teaching maternity unit. Br J Anaesth

1996;76:680–4. 18. Gataure PS, Hughes JA. The laryngeal mask airway in obstetrical anaesthesia. Can J Anaesth 1995;42:130–133. 19. White A, Sinclair M, Pillai R. Laryngeal mask airway for coronary artery bypass grafting. Anaesthesia 1991;46:234. 20. Fullekrug B, Pothmann W, Druge G. An unconventional use of the laryngeal mask for the therapy of a postoperative atelectasis-induced

respiratory insufficiency [in German]. Anaesthesiol Intensivmed Notfallmed Schmerzther 1993;28:187–9. 21. Groudine SB, Lumb PD, Sandison MR. Pressure support ventilation with the laryngeal mask airway: a method to manage severe reactive airway disease postoperatively. Can J Anaesth 1995;42:341–3.

22. Groudine SB, Lumb PD. Noninvasive ventilatory support with the laryngeal mask airway. Am J Anesthesiol 1996;2:124–128. 23. Glaisyer HR, Parry M, Bailey PM. The LMA for the application of postoperative CPAP. Can J Anaesth 1997;44:784–5. 24. Voyagis GS, Palumbi C. Use of the laryngeal mask for management of the compromised airway: a case report. Middle East J Anesthesiol

1998;14:275–80. 5. Sasano H, Sasano N, Hattori T, et al. Tracheal tube/laryngeal mask exchange to prevent coughing in lung volume reduction surgery [in Japanese]. Masui 2000;49:278–81.


LMA Proseal Han TH, Brimacombe J, Lee EJ, Yang HS. The laryngeal mask airway is effective and

probably safe in selected healthy parturients for elective Cesarean section. Can J Anaesth 2001;48:1117–21.

Awan R, Nolan JP, Cook TM: Use of a ProSeal laryngeal mask airway for airway maintenance during emergency caesarean section after failed tracheal intubation. Br J Anaesth 2004; 92:144–146

Brown NI, Mack PF, Mitera DM, et al: Use of the ProSeal laryngeal mask airway in a pregnant patient with a difficult airway during electroconvulsive therapy. Br J Anaesth 2003; 91:752–754

Bullingham A: Use of the ProSeal laryngeal mask airway for airway maintenance during emergency caesarean section after failed intubation. Br J Anaesth 2004; 92:903

Keller C,Brimacombe J,Lirk P,Pühringer F.Failed Obstetric Tracheal Intubation and Postoperative Respiratory Support with the ProSeal™ Laryngeal Mask Airway

]


Conclusioni sulla intubazione difficile

Mettere a punto l’organizzazione;informazione,visite,educazione,Sellick…...

valutare le vie aeree adottare una pratica che sottolinei l’ossigenazione

ed il risveglio della madre praticare regolarmente ! evitare l’AG.


Intubazione Adiuvanti: NMB:

» Succi 1-1.5 mg/kg» Rocuronium 1.2 mg/kg(60”)-0.6 mg/kg(80”)

– Abouleish E, Abboud T, Lechevalier T, Zhu J, Chalian A, Alford K. Rocuronium (Org 9426) for Caesarean section. British Journal of Anaesthesia 1994; 73:336-341.

» Vecuronium 0.2 mg/kg» ???» Atracurium peggio della DTC per il neonato


Perreault C,Guay J,Gaudreault P,Cyrenne L,Varin F.Residual curarization in the neonate after cesarean section.Can J.Anesth 1991;39:587

– ABSTRACT: The transplacental transfer and the neonatal effects of atracurium 0.3 mg × kg-1 (ED95) were compared with those of d-tubocurarine at the usual clinical dose of 0.3 mg × kg-1 (ED90) in 46 patients undergoing elective Caesarean section. The atracurium group (25 patients) was similar to the d-tubocurarine group (21 patients) as far as age, parity and time intervals between precurarization, induction, skin incision, muscle relaxant administration, hysterotomy and birth. The transplacental transfer of atracurium was lower than that of d-tubocurarine, with a feto-maternal ratio of 9 ± 3% for atracurium and 12 ± 5% for d-tubocurarine (P < 0.05). The transplacental transfer of laudanosine was low at 14 ± 5%, with blood levels of 0.101 ± 0.032 mM × L-1 in the umbilical vein. Newborns in the two groups were comparable in terms of Apgar scores at one, five and ten minutes, as well as for NACS scores (neurological and adaptive capacity scoring test) at two and 24 hours after birth. However, at 15 min after birth, only 55% of newborns in whom the mothers received atracurium had a normal NACS score (³ 35/40) compared with 83% of newborns in whom the mothers received d-tubocurarine (P < 0.05). Further analysis of the five variables related to active muscle tone revealed that the modal score for active extension of the neck of newborns from the atracurium group was lower than for newborns from the d-tubocurarine group (P < 0.01). This was compatible with the effect of residual curarization among newborns in whom the mothers received atracurium. However, this effect was transient since there was no difference found between the two groups at two and 24 hr after birth. Furthermore, no newborn had clinical signs of respiratory distress. In conclusion, atracurium given at a dose of 0.3 mg × kg-1 for Caesarean section may lead to partial residual curarization of neonates 15 min after birth.


Fattori di rischio associati alla intubazione tracheale

difficile (da Rocke DA, Murray WB, Rout CC, Gouwns E: Relative risk analysis of

factors associated with difficult intubation in Obstetric anesthesia. Anesthesiology 1992;

77:67‑73.)

Caratteristica anatomica» Mallampati 4» mandibola recedente» protrusione incisivi

mascellari» Mallampati 3» Collo corto» Mallampati 2» Mallampati 1

Rischio relativo

» 11.30» 9.71» 8.00

» 7.58» 5.01» 3.23» 1.00


FiO2

– Piggott SE, Bogod DG, Rosen M, Rees GAD: Isoflurane with either 100% oxygen or 50% nitrous oxide in oxygen for cesarean

section. Br J Anaesth 61:255, 1990– 34 Bogod DG, Rosen M, Rees GAD: Maximum

Fi02 during cesarean section. Bir J Anaesth 61:255,1988


Khaw, K S.; Wang C C, Kee W D. Ngan Pang C P, Rogers, M.S.Effects of high oxygen inspired fraction during electice caesarean section under spinal anesthesia on maternal and fetal oxygenation and lipid peroxidation.BJA 2002;88:18-23


Ossigenazione O2 50% + N2O 50% vs O2 100%:

» UvpO2 + alta di 6-7 torr;pH o BD no diff!– Bogod BJA 1988,PIGGOTT BJA 1989

» Se si aum FiO2,aumenta anche il vapore!!!» Aumentare la FiO2 nell’intervallo IU-D non

porta aumenti nella ossigenazione fetale(poco tempo??)

» Perreault, C., Blaise, G. A; Meloche, R..» Maternal inspired oxygen concentration and fetal oxygenation

during cesarean section.Can.Anesth.Soc.J.1992 ;39:155


Kee WD Ngan, Khaw KS,Ma KC,Wong ASY, Lee B. Randomized double blind comparison of different oxygen inspired fractions during general anesthesia for cesarean section.BJA 2002;89:556. We randomized patients having elective Caesarean section to receive one of the following:

FIO2 0.3, FIN2O 0.7 and end-tidal sevoflurane 0.6% (Group 30, n=20); FIO2, 0.5, FIN2O 0.5 and end-tidal sevoflurane 1.0% (Group 50, n=20), or FIO2 1.0 and end-tidal sevoflurane 2.0% (Group 100, n=20) until delivery. Neonatal outcome was compared biochemically and clinically.

Results. At delivery, for umbilical venous blood, mean PO2 was greater in Group 100 (7.6 (SD 3.7) kPa) compared with both Group 30 (4.0 (1.1) kPa, P<0.0001) and Group 50 (4.7 (0.9) kPa, P=0.002) and oxygen content was greater in Group 100 (17.2 (1.6) ml dl-1) compared with both Group 30 (12.8 (3.6) ml dl-1, P=0.0001) and Group 50 (13.8 (2.6) ml dl-1, P=0.0001). For umbilical arterial blood, PO2 was greater in Group 100 (3.2 (0.4) kPa) compared with Group 30 (2.4 (0.7) kPa, P=0.003), and in Group 50 (2.9 (0.8) kPa) compared with Group 30 (2.4 (0.7) kPa, P=0.04); oxygen content was greater in Group 100 (10.8 (3.5) ml dl-1) than in Group 30 (7.0 (3.0) ml dl-1, P<0.01). Apgar scores, neonatal neurologic and adaptive capacity scores, and maternal arterial plasma concentrations of epinephrine and norepinephrine before induction and at delivery were similar among groups. No patient reported intraoperative awareness.

Conclusions. Use of FIO2 1.0 during general anaesthesia for elective Caesarean section increased fetal oxygenation.


Kee WD Ngan, Khaw KS,Ma KC,Wong ASY, Lee B. Randomized double blind comparison of different oxygen inspired fractions during general anesthesia for cesarean section.BJA 2002;89:556.

FiO2 FiN2O Sevoflurane %

0.30 0.70 0.6

0.50 0.50 1

1 0 2


Kee WD Ngan, Khaw KS,Ma KC,Wong ASY, Lee B. Randomized double blind comparison of different oxygen inspired fractions during general anesthesia for cesarean section.BJA 2002;89:556.


Ossigenazione(e awareness)

FiO2 1:UV pO2> FiO2 0.50(Bogod et al.Br.J.Anaesth 1988;61:255-62 per AG .e Ramanathan Anesth Analg 1982;61:576-81. per analg p.d.

se N2O 50% ,MAC 0.5 -0.7 se FiO2 1,MAC 1.2:quindi:

» haloth 1.1 *5 min,poi 0.75» enflur 2.5 * 5 min,poi 1.7» isofl 1.8 * 5 min,poi 1.2» sevor 2.2 * 5 min,poi 1.5


Perreault, C., Blaise, G. A; Meloche, R. Maternal inspired oxygen concentration and fetal oxygenation during cesarean section.Can.Anesth.Soc.J.1992 ;39:155.

» » This study was designed to determine whether fetal arterial and venous PO2

could be increased by increasing maternal FIO2 in the period between hysterotomy and birth. Two groups of ten patients were studied. All were anaesthetised with the same technique except for the FIO2 after hysterotomy. One group inspired 50% oxygen and the second group inspired 100% oxygen. Although the maternal arterial PO2 was higher at birth in the 100% O2 group (177.4 ± 42.3 mmHg vs 281.0 ± 94.2 mmHg), there were no differences between the arterial umbilical cord PO2 (19.3 ± 5.7 mmHg vs 18.5 ± 7.3 mmHg) and the venous umbilical cord PO2 (31.1 ± 7.6 mmHg vs 33.0 ± 10.8 mmHg). Awareness was present in one patient in the 50% O2 group and in four patients in the 100% O2 group but this difference was not statistically significant. It is concluded that a higher inspired maternal oxygen concentration between hysterotomy and birth does not result in any increase in fetal PO2.


Mantenimento AG Postpartum

N2O/O2 66/33,70/30……. Alogenato????(atonia uterina!!!) Amnesia

» (diazepam 5-10 mg,midazolam 2-5 mg) Analgesia:morfina 0.2-0.3

mg/kg,fentanile 2-3 microgr /kg Ripetere ipnotico


Bilancia dell’AG

Anestesia materna

Minima depressione neonatale


Indicazioni per gli anest.alogenati

Potenziamento della AG:riduzione delle catecolamine materne……Crawford??

Riduzione o eliminazione della sensazione di veglia materna:paziente addormentata e inconscia

Condizioni operative ottimali


Effetti collaterali

Alterazioni emodinamiche Atonia uterina…


Vantaggi degli alogenati Permettono alte FiO2 Possono aum il flusso ematico uterino diminuendo la

vasocostrizione delle art uterine mediata dalle catecolamine materne

Previene l’ awareness…ma sono necessari alcuni min prima di ottenere un MAC ragionevole (sevoflurane o desflurane equilibrano + rapidamente


Svantaggi degli alogenati

Sanguinam. uterino Bassi punteggi di Apgar? Bassi punteggi nelle

valut.neurocomportamentali Inquinamento ambientale


Modificazioni indotte dalla gravidanza che influenzano l’anest

inalatoria

Soglia per dolore e fastidio

MAC richieste :25%‑40%

» Datta et al,Chronically administered progesterone decreases halothane requirements in rabbits.Anesth.Analg. 1989;68:46-50).

FRC


Chan et al.Minimum Alveolar Concentration of Halothane and Enflurane Are Decreased in Early Pregnancy Anesthesiology85:782-6, 1996


Riduzione MAC in gravidanzaGin T, Chan MTV: Decreased minimum alveolar concentration of isoflurane in pregnant humans. ANESTHESIOLOGY 81:829-32, 1994 ; Chan et al.Minimum Alveolar Concentration of Halothane and Enflurane Are Decreased in Early Pregnancy Anesthesiology 85:782-6, 1996

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

non pregnant pregnant

isoflurane

halothane

enflurane


Gin T, Chan MTV: Decreased minimum alveolar concentration of isoflurane in pregnant humans. ANESTHESIOLOGY 81:829-32, 1994 Minimum alveolar concentration (MAC) is decreased in pregnant animals, but this change has not been

demonstrated in humans, probably because of ethical considerations. It is less problematic to determine MAC in pregnant women undergoing termination of pregnancy, however, and therefore we compared the MAC of isoflurane in these women with the MAC in matched nonpregnant women. METHODS: Patients underwent inhalational induction of anesthesia with isoflurane and tracheal intubation. MAC was determined in each patient by testing the response to a 10-s, 50-Hz, 80-mA transcutaneous tetanic electrical stimulus to the ulnar nerve at varying concentrations of isoflurane. The end-tidal concentration of isoflurane was kept constant for 10 min before each stimulus and the concentration of isoflurane ultimately varied in steps of 0.05% until we obtained a sequence of three alternate responses (move, not move, move) or (not move, move, not move). MAC for each patient was taken as the mean of the two concentrations just permitting and just preventing movement. MAC for the group was taken as the median of the individual MAC values. A blood sample was taken immediately before induction of anesthesia for measurement of progesterone concentrations. Data were compared between groups by the Mann-Whitney test. RESULTS: The median (range) MAC for isoflurane in the pregnant group, 0.775% (0.675-0.825), was less than that in the nonpregnant group, 1.075% (1.025-1.175) (P < 0.001). The median (range) plasma progesterone concentration in the pregnant group, 63.4 (0.8-106) nM, was greater than that in the nonpregnant group, 8.4 (0.7-66) nM (P < 0.02). CONCLUSIONS: The MAC of isoflurane was reduced by 28% in pregnant women at 8-12 weeks' gestation compared with that of nonpregnant controls.


Chan M,Mainland P, Gin TMinimum Alveolar Concentration of Halothane and Enflurane Are Decreased in Early Pregnancy Anesthesiology85:782-6, 1996 The MAC of halothane and enflurane were compared in pregnant women undergoing elective termination of

pregnancy and in nonpregnant women. Methods: We studied 16 pregnant women scheduled for termination of pregnancy at 8 to 13 weeks gestation and

16 nonpregnant patients undergoing laparoscopic sterilization. Eight patients in each group received halothane and the others received enflurane. After inhalational induction of anesthesia and tracheal intubation, MAC was determined in each patient by observing the motor response to a 10-s, 50-Hz, 80-mA transcutaneous electric tetanic stimulus to the ulnar nerve at varying concentrations of either halothane or enflurane. The end-tidal concentration of inhalational anesthetic was kept constant for at least 15 min before each stimulus and the concentration was varied ultimately in steps of 0.05 vol% (halothane) or 0.10 vol% (enflurane) until a sequence of three alternate responses (move, not move, move) or (not move, move, not move) was obtained. Minimum alveolar concentration for each person was taken as the mean of the two concentrations just permitting and just preventing movement, and MAC for the group was the median of individual MAC values. Confidence intervals were calculated for the percentage decrease in MAC for pregnant women compared with nonpregnant women.

Results: The median (range) MAC of halothane, 0.58 vol% (0.53 to 0.58), and enflurane, 1.15 vol% (0.95—1.25), in the pregnant women were less than those in the nonpregnant women, 0.75 vol% (0.70 to 0.78), P = 0.0005 and 1.65 vol% (1.45 to 1.75), P = 0.0007, respectively. The percentage decrease (95% CI) in MAC for pregnant women was 27% (20 to 27%) for halothane and 30% (24 to 36%) for enflurane.

Conclusions: The MAC of halothane and enflurane were reduced by a similar degree in pregnant women at 8 to 13 weeks gestation compared with nonpregnant women.


Avoid maternal hyperventilation


Conseguenze della iperventilazione materna(da Shnider,Moya,Levinson,Cosmi…)


King H, Ashley S, Brathwaite D, Decayette J, Wooten D: Adequacy of

general anesthesia for cesarean section. Anesth Analg 77:84-8, 1993

020406080

100120

lryn

gosc

opy,

IOT

skin

inc

1 m

in

2min

3min

% of patients

Lifescanfinger flexionhand squeezelacrimation

Isolated arm technique

Tps/scc/iot/N2O 50/haloth 0.5%

ind inc

68-130 sec

delivery220-367 sec.


Characteristics of inhaledanesthetics

Decomposesnone2,424150,20,75197,4halothane

Stablemoderate

1,917556.51,68184,5enflurane

Stablemoderate

1.423848.51.15184,5isoflurane

decomposesno0,6016058.52.0200sevoflurane

stableno0,4739000gas

-8810544N2O

stableyes0,4266323.56168desflurane

Soda limepungencyBlood/gas partitioncoeff.

Vapor press.

Bolingpoint

MACmwagent


Rapidità della crescita della concentrazione alveolare (Fa)di anestetico in relazione alla concentrazione inspirata (Fi)


Navarro EM.Desflurane general anesthesia for cesarean section compared with isoflurane and epidural anesthesia.Anesthesiol.Intensivmed.Notfallmed.Schmerzther 2000;35;232-6. Desflurane 2.5% vs isofl 0.5% vs epid 15 ml ropi 0.75% +

fent 100 microgr N2O 50% intraop haemodynamics blood loss maternal awareness Apgar scores 1-5 min NACS 2-24 h Ega UV/MV


Navarro II

No diff among the 3 groups except a more rapid emergence following des.


Olthoff D,Rohrbach A. Sevoflurane in obstetric anesthesia.Anesthesist 1998;47,suppl 1,s 63-9

Sevo > isofl and no outcome diff with epid,

sevo> isof in pEEG monitoring……...


Attenuazione della risposta catecolaminica


Shnider et al: Uterine blood flow and plasma norepinephrine changes during maternal stress in the pregnant ewe. ANESTHESIOLOGY 50:524-7, 1979

-80

-60

-40

-20

0

20

40

60

1 2 3 4 5

min

% change from basal

MAPNorepiuter.Blood flow

\

Electrically induced stress 30-60 sec,loud noises,sudden movement of personnel...


Modificazioni del flusso ematico uterino durante

anestesia nella scimmia gravida (from Shnider,Levinson,etc..)

-20-15-10-505

101520

% change from control

anest without stim anest withstimulation

N2O 50%N2O 50% +haloth 0.5%N2O 50% + enfl 1%


Maternal awareness of surgery and birth after barbiturate-relaxant

induction &...

02468

101214161820

%

maternal awareness

N2O 50%

N2O 67-75%

N2O 25-40%+halo0.4%N2O 50%+haloth0.3%N2O 50%+enfl 0,75

N2O 33%+metx 0.1%

N2O 50+ isof 0,75%


Lyons G, Macdonald R: Awareness during caesarean section. Anaesthesia 46:62-4, 1991

1982-1989 > 3000 patients questioned about recall and dreaming after GA for

C/S 28 (0.9%) patients were able to recall something of their operation

189 (6.1%) reported dreams. Recollections of surgery were confined to manipulations, noises and voices. None of our patients complained of pain at the time of interview, although one since has.


Incidenza della awareness(from various sources)

0

2

4

6

8

10

12

14

16

%

incidence

C/Scard.surgnon card. Surgmajor trauma

0.4


Domino K, Posner KL, Caplan, R,Cheney F. Awareness during Anesthesia : A Closed Claims analysis.Anesthesiology90:1053-61, 1999.

Liability riskRischio della responsabilità


Dwyer R, Bennett HL, Eger EI II, Peterson N: Isoflurane anesthesia prevents unconscious

learning. Anesth Analg 75:107-12, 1992

Parecchi autori riportano che la prevenzione del ricordo cosciente di eventi si ottiene con concentrazionei relativamente basse di anestetici volatili .

Isoflurane 0.6 MAC previene il ricordo conscio e l’apprendimento incosciente di informazioni fattuali e i suggerimenti comportamentali


Moir, D. D .ANAESTHESIA FOR CAESAREAN SECTION An Evaluation of a Method using Low Concentrations of

Halothane and 50 per cent of Oxygen Br. J. Anaesth. 1998; 80:690-696

The addition of 0.5 per cent of halothane vapour to a basic thiopentone, nitrous oxide, muscle relaxant anaesthetic technique does not increase blood loss at Caesarean section, does not affect the incidence of hypotension, and is likely to ensure unconsciousness. By permitting the administration of 50 per cent of oxygen with nitrous oxide, the condition of the newborn infant is likely to be improved. The use of 0.8 per cent of halothane vapour does not increase blood loss but is associated with a high incidence of hypotension and for this reason is not advisable.


Eger, Edmond I, II,.Age, Minimum Alveolar Anesthetic Concentration, and Minimum Alveolar Anesthetic Concentration-Awake .Anesthesia & Analgesia 2001; 93:947-953 MAC-Awake is also close to the anesthetic

concentration suppressing memory and learning » Dwyer R, Bennett HL, Eger EI, Heilbron D. Effects of isoflurane and nitrous

oxide in subanesthetic concentrations on memory and responsiveness in volunteers. Anesthesiology 1992; 77:888-98.

» Dwyer R, Bennett HL, Eger EI, Peterson N. Isoflurane anesthesia prevents unconscious learning. Anesth Analg 1992; 75:107-12.

» Chortkoff BS, Bennett HL, Eger EI. Subanesthetic concentrations of isoflurane suppress learning as defined by the category-example task. Anesthesiology 1993; 79:16-22.

» Chortkoff BS, Gonsowski CT, Bennett HL. Subanesthetic concentrations of desflurane and propofol suppress recall of emotionally charged information. Anesth Analg 1995; 81:728-36.


MAC AWAKEEnd-tidal anaesthetic concentrations at first eye opening in response to a verbal command during

recovery from anaesthesia MAC-Awake, the end-tidal anesthetic concentration at 1 atm that suppresses the appropriate

response to command in 50% of subjects.

Autori Rivista/anno MAC MAC awakeGAUMANN Br. J. Anaesth. 1992;

68:81-4Isof 1.2 0.30%=0.25 Mac

Haloth 0.8 0.45%=0.50/0/59 mac

Enflurane 1.7 0.45%=0.27 macKATOH Br. J. Anaesth. 1992;

69:259-62Sevo 0.61%=0.33 mac

ISOf 0.39%=0.33 mac

isof 0.41%Suzuki Anesth Analg 1998;

86:179–83sevoflurane 0.7%

Katoh Anesth Analg 1993; 76:348–52

sevo 0.62%


Outcome dopo GA


C/S elettivi:Durata della GA o Epidurale

antepartum e % di Apgar tra 7-10 (da dati di Robin,Shnider,Levinson---)

0102030405060708090

100

% 7-10 Apgar scores

GA epid

<5

6;10

11;20

21;30

31;60

Min:


I-D & UI-D

Ma + importante che la durata totale fra

induzione e parto (I-D) ,quello critico è

L’ intervallo incis.uterina /parto (UI-D),che ha dimostrato correlazione con la ipossia fetale e l’acidosi


GA e depressione del neonato

0102030405060708090

100

Apgar 1' Apgar 5'

spinal

epidural

GA


Efetti fetali e neonatali degli alogenati

Maggiore frequenza di resuscitazione neonatale dopo AG vs regionale» ONG BY,Cohen MM,Palahniuk

RJ:Anesthesia for cesarean section: effects on neonates.Anesth.Analg 1989;68:270-275.


Ong BY,Cohen MM,Palahniuk RJ.Anesthesia for cesarean section:effects on neonates.AA

1989;68:270-5.

3940 C/S;12.5% of neonates Apgar < 4 1.5% 5 min Apgar score < 4 Lista dei fattori associati con bassi punteggi di Apgar a 1 min

» primiparià» grande multiparità» Patologie antepartum (preeclampsia,diabetes mellitus,mal cardiache materne,

isoimmunizzazione RH , emorragia precoce amtepartum)» Presenza di fetal distress» Bassa età gestazionale » Uso di narcotici durante travaglio » Presentazione podalica» C/S non elettivo» GA


Ong et al.Anesthesia for cesarean section:effects on neonates.AA

1989;68:270-5.

Una analisi multivariata che ha controllato per molte variabili ha dato :

Rischio + alto per bassi valori di Apgar a 1 min GA 3 >reg(2.5-3.88)

Rischio + alto per bassi valori di Apgar a 5 min; GA 3> reg(1.81-7)

Necessità di resuscitazione : GA 2> reg(1.32-2.90)


Destino del neonato dopo C/S a seconda della tecnica anestetica:piccoli con 1 min Apgar < 4 (%)

Ong BY,Cohen MM,Palahniuk RJ.Anesthesia for cesarean section:effects on neonates.AA 1989;68:270-5.

0

5

10

15

20

25

30

35

40

45

reg GA

elective

fetal distress

failure to progress

0.05

0.01

0.001


Piccoli con 5 min Apgar 0-4(%) Ong BY,Cohen MM,Palahniuk RJ.Anesthesia for cesarean section:effects on

neonates.AA 1989;68:270-5.

0

1

2

3

4

5

6

7

8

9

reg GA

elective

fetal distress

failure to progress

0.01

0.01


Neonati che hanno necessitato O2 per maschera Ong BY,Cohen MM,Palahniuk RJ.Anesthesia for cesarean section:effects on

neonates.AA 1989;68:270-5.

0

5

10

15

20

25

reg GA

elective

fetal distress

failure to progress

0.01

0.001


Neonati che hano richiesto iot e IPPV(%) Ong BY,Cohen MM,Palahniuk RJ.Anesthesia for cesarean section:effects on

neonates.AA 1989;68:270-5.

0,0

5,0

10,0

15,0

20,0

25,0

30,0

35,0

40,0

45,0

reg GA

elective

fetal distress

failure to progress

0.001


Morti neonatali

Ong BY,Cohen MM,Palahniuk RJ.Anesthesia for cesarean section:effects on neonates.AA 1989;68:270-5.

0

1

2

3

4

5

6

7

reg GA

elective

fetal distress

failure to progress


Gregory FA, Wagde JG, Biehl DR, Ong BY, Sitar DS. Foetal anaesthetic requirements (MAC) for halothane. Anesth Analg 1983;62:9‑14.

Bachman CR, Biehl DR, Sitar DS, Cumming M, Pucci W. Isoflurane potency and cardiovascular effects during short exposures in the foetal lamb. Can Anaesth Soc

J 1986;33:41‑7.

MAC è significativamente più basso nei feti agnelli che nei neonati agnelli > 24 h di età. » Questi dati suggeriscono che i neonati subito dopo il

parto possono essere particolarmente sensibili agli anest.inalatori ,per cui quelli esposti agli anest.generali possono essere meno vigorosi alla nascita .Dopo avere assistito la respirazione e l’espirazione degli anest inalati questi infanti sono simili agli altri


La depressione della contrattilità uterina da

alogenati sub Mac ripercussioni cliniche sulle

perdite ematiche?


Postpartum blood loss:Piggott SE,Bogod DG,Rosen M,Rees GAD,Harmer M.Isoflurane with

either 100% oxygen or 50% nitrous oxide in oxygen for caesarean section.BJA 1990;65:325-

29.

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

HB decrease, %

N2O50+haloth

0.5

O2100%+haloth 0,75

02 100% +enflur 1,7

02 100% +isofl 1,2%

electiveemergent


Influenza dell’anestesia sulle perdite ematiche nel C/S(Moir DD.Anesthesia for cesarean section:an evaluation of a method using

low concentrations of halothane and 50% of oxygen.BJA 1970;42:136-142.

0

100

200

300

400

500

600

700

800

ml

blood loss

N2O 70N2O50+ aloth 0,5N2O 50+ haloth 0,8epid analg


HCT :valori prima e dopo C/S:(from Thirion et al.Maternal blood loss associated with low dose alothane

administration for caesarean section.Anesthesiology 1988;69:a693)

0

5

10

15

20

25

30

35

40

%

halothpredelivery

aloth pre& post epidural

Hct preopHCTday 1Hct day 2


Conclusioni sugli alogenati e le perdite ematiche

Decremento nella contrattilità e tono uterino dose dipendente

Ma nessun incremento nelle perdite ematiche se somministrati in concentrazioni basse/moderate:

haloth 0.1-0.8 enflurane 0,5-1,5 isoflurane 0,75 Sevoflurane 0.8-1.5…..


In ogni caso;dopo il parto …...

Stop l’anest volatile continua N2O(aum al 60-65%) Somministra una II dose di ipnotico (TPS

100-150 mg;propofol 60-100 mg + Un potente analgesico :fentanyl 100-150

microgr..… nmb se necessari……


Interazioni degli anest volatili con:

Potenziamento dei miorilassanti nifedipina;

» aum degli eff,coll. con aloth,enfl,isof( ma non su animali gravidi)– Rosone et al..Hemodynamic responses to nifedipine in dogs anesthetized

with halothane. Anesth.Analg 1983;62:903-908.)

Nicardipina: aum dell’atonia uterina ,non facilmente reversibile post partum con oxitocin:

– Csapo et al.Deactivation of the uterus during normal and premature labor by the calcium antagonist nicardipine.Am,J.Obstet.Gynecol. 1982;142:483-91


Induzione AG

Tps < 7 mg/kg metohexital 1 mg/kg ketamina 1-1.5 mg/kg etomidate 0.25-0.30 mg/kg midazolam 0.2-0.3 mg/kg propofol 2.5 mg/kg non hanno significativi effetti sul

destino neonatale


Ipnoinduttori e C/S


Gin T,O'Meara ME,Kan AF,Leung RKW,Tan P,Yau G.PLASMA CATECHOLAMINES AND NEONATAL CONDITION AFTER INDUCTION OF ANAESTHESIA WITH PROPOFOL OR THIOPENTONE AT CAESAREAN SECTION Br. J. Anaesth. 1993; 70:311-6

C/S elettivi,feto singolo TPS 4 mg/kg vs propofol 2 mg/kg + succi/ iot dopo 1 min/ atrac/isof

TPS propofol MAP + 29 (SD 15) mm Hg + 18 (14) mm Hg)

Max noradr conc 413 (177) pg ml-1 333 (108) pg ml-1 Max adr conc ==== ===

Apgar,NACS,catecol ombelicali,EGA,CO2 simili nei 2 gruppi

Propofol attenua la risposta ipertensiva e catecolaminica all’iot;senza differenze di outcome


Gin T,Yau G,Jong W,Tan P,Leung RKW,Chan K. DISPOSITION OF PROPOFOL AT CAESAREAN SECTION AND IN THE POSTPARTUM PERIOD CAN J ANAESTH 1991 / 38: 1 / 31-6

ABSTRACT: We have compared the pharmacokinetics of a bolus

dose of propofol 2 mg kg-1 in eight patients undergoing Caesarean section with those in eight postpartum patients undergoing sterilization by mini-laparotomy. The Caesarean section group had a total body clearance of (median) 31.5 (range 24.4–53.3)ml min-1 kg-1, apparent volume of distribution at steady state 5.10 (2.46–6.61) litre kg-1 and mean residence time 161 (52.3–251)min; values for the postpartum group were 33.8 (21.5–47.2) ml min-1 kg-1, 5.17 (3.47–8.09) litre kg-1 and 163 (92.3–238) min, respectively. The 95% confidence interval for the umbilical venous to maternal venous ratio of propofol at delivery was 0.62–0.86. Plasma protein binding studies showed there was less unbound propofol in maternal plasma (1.28–2.29%) compared with umbilical plasma (2.08–3.88%) (P < 0.01). Neonatal concentrations of propofol were greater than maternal concentrations at 2 h and were in the range 0.05–0.11 mg ml-1 at 4 h



Gin T,Yau G,Chan K,Gregory MA,Oh TE.Disposition of propofol infusions for Caesarean section.CAN J ANAESTH 1991 / 38: 1 / pp31-6

ABSTRACT: The disposition of propofol was studied in women undergoing elective Caesarean

section. Indices of maternal recovery and neonatal assessment were correlated with venous concentrations of propofol. After induction of anaesthesia with propofol 2.0 mg × kg-1, ten patients received propofol 6 mg × kg-1 × hr-1 with nitrous oxide 50 per cent in oxygen (low group) and nine were given propofol 9 mg × kg-1 × hr-1 with oxygen 100 per cent (high group). Pharmacokinetic variables were similar between the groups. The mean ± SD Vss = 2.38 ± 1.16 L × kg-1, Cl = 39.2 ± 9.75 ml × min-1 × kg-1 and t1/2b = 126 ± 68.7 min. At the time of delivery (8–16 min), the concentration of propofol ranged from 1.91–3.82 mg × ml-1 in the maternal vein (MV), 1.00–2.00 mg × ml-1 in the umbilical vein (UV) and 0.53–1.66 mg × ml-1 in the umbilical

artery (UA). Neonates with high UV concentrations of propofol at delivery had lower neurologic and adaptive capacity scores 15 minutes later. The concentrations of propofol were similar between groups during the infusion but they declined at a faster rate in the low group postoperatively. Maternal recovery times did not depend on the total dose of propofol but the concentration of propofol at the time of eye opening was greater in the high group than the low group (1.74 ± 0.51 vs 1.24 ± 0.32 mg × ml-1, P < 0.01). The rapid placental transfer of propofol during Caesarean section requires propofol infusions to be given cautiously, especially when induction to delivery times are long.








The mean UV/MV ratio of 0.52 is lower than the 0.65–0.85 seen after bolus induction doses of propofol and the 0.76 during an infusion study with I-D times of 7–31 min. Our I-D times (8–16 min) are shorter than the previous infusion study and the lower UV/MV would indicate there is still a gradient for placental transfer from the maternal to fetal circulations. The mean UA/UV ratio of 0.61 is similar to the 0.70 with previous infusions and 0.67 after bolus induction with short I-D times of 4–7 min. This indicates continuing fetal tissue uptake. However, bolus induction studies with longer I-D times have UA/UV ratios of 1.09 and 1.07 which imply more complete fetal distribution.

Neonatal depression in the low-infusion group was similar to that found after an anaesthetic technique using thiopentone for induction of anaesthesia and nitrous oxide and enflurane for maintenance of anaesthesia. The negative correlation between NACS and UV concentrations of propofol provides some evidence of neonatal depression due to propofol. Although infusion times were too short to differentiate maternal concentrations of propofol between the two groups, a high-dose infusion combined with a long induction to delivery time is likely to produce high UV concentrations of propofol and low neonatal NACS scores. The neonatal elimination of propofol is slower than the maternal elimination (unpublished observations). Neonatal glucuronidation is poorly developed but sulphation activity is similar to that found in adults.


Kee WD Ngan,Khaw KS, Ma ML., RN,Mainland P-A, Gin T. Postoperative Analgesic Requirement After Cesarean Section: A Comparison of Anesthetic Induction with Ketamine or Thiopental. Anesth Analg 1997; 85:1294

ABSTRACT: In a randomized, double-blind study, we compared postoperative pain and analgesic requirement in patients who underwent elective cesarean section under general anesthesia induced with thiopental 4 mg/kg (n = 20) or ketamine 1 mg/kg (n = 20). Anesthesia was maintained with nitrous oxide and isoflurane. Postoperative analgesia was provided by patient-controlled analgesia (PCA) using morphine. Median (range) time to first PCA demand was greater in the ketamine group (28 [3–134] min) compared with the thiopental group (20.5 [3–60] min; P = 0.04). Median (range) morphine consumption over 24 h was less in the ketamine group (24.3 [3–41] mg) compared with the thiopental group (35 [4–67] mg; P = 0.017). Visual analog scale pain scores were similar between groups. No patients had recall of intraoperative events or unpleasant dreams. Two patients in the thiopental group and one patient in the ketamine group had pleasant intraoperative dreams. Apgar scores were similar between groups. Median umbilical venous pH was higher (7.33 vs 7.31; P = 0.04) and attributable to lower median umbilical venous PCO2 (5.72 vs 6.14 kPa; P = 0.02) in the ketamine group compared with the thiopental group. Induction of anesthesia for cesarean section using ketamine is associated with a lower postoperative analgesic requirement compared with thiopental. Implications: Patients who had anesthesia for cesarean section induced with ketamine required less analgesic drugs in the first 24 h compared with patients who received thiopental. Ketamine, unlike thiopental, has analgesic properties that may reduce sensitization of pain pathways and extend into the postoperative period.


Kee WD Ngan,Khaw KS, Ma ML., RN,Mainland P-A, Gin T. Postoperative Analgesic Requirement After

Cesarean Section: A Comparison of Anesthetic Induction with Ketamine or Thiopental. Anesth

Analg 1997; 85:1294


Vantaggi della ketamina Minor ipotensione Possibilità di iniezione im

– Lum Hee WC,Metias VF.Intramuscular ketamine in a parturient in whom pre-operative intravenous access was not possible . Br. J. Anaesth. 2001; 86

Maggiore profondità anestetica» Gaitini L,Vaida S,Collins G,Somri M,Sabo E.Awareness detection

during Caesarean section under general anaesthesia using EEG spectrum analysis .CAN J ANAESTH 1995 / 42: 5 / pp377-81

Minor necessità di analgesia postop


Protezione emodinamica dallo stress dell’IOT

Oppioidi a breve azione:» alfentanil 10 microgr/kg

Gin, T, Ngan-Kee, W D,Siu YK,Stuart JC,Tan P, Lam KK.Alfentanil given immediately before induction of general anesthesia for cesarean section.AA 2000;90:1467.

remifentanil 1-1.25 microgr/kg bolo lento o inf cont– Ma PAS – O'Hare R, McAtamney D,Mirakhur RK, Hughes D, Carabine U.Bolus dose of remifentanil

for control of haemodynamic response to tracheal intubation during rapid sequence induction of anesthesia.BJA 1999;82:283.


Kan RE.Hughes S,Rosen MA,Kessin C,Preston PG,Lobo EP.Intravenous Remifentanil: Placental

Transfer, Maternal and Neonatal Effects.Anesthesiology,98:1467-74, 1998


Schaut DJ Sevoflurane inhalation induction for emergency caesarean section in a parturient with no intravenous access.Anesthesiology 1997;86:1392.

Sevo 8%;incoscienza in 30”;5 min dopo i.v. per paralisi e iot


Dopo il parto

Anestesia/analgesia indifferente? A patto che non deprima la contrattilità

uterina……..


Risveglio Estubare solo alla ripresa di una normale ventilazione e

normale funzione neuromuscolare! Controllare forza !! Se non avete ancora svuotato lo stomaco,fatelo prima del

risveglio!» SNG/lavaggio/antiacido per contatto(citrato di sodio)

Profilassi del PONV?» Valutazione dei fattori di rischio…» Tenete conto dedlla profilassi ab

ingestis:ranitidina+metoclopramide


THE END


Chemioprofilassi dell’ab ingestis


Inhalation anestesia for caesarean section :why?

How?

C.Melloni

Servizio di Anestesia e Rianimazione

Ospedale di Faenza(RA)


Changes in obstetric anesthesia(C/S) in USA(Hawkins et al,Obstetric anesthesia workforce

survey-1992 versus 1981.Anesthesiology 1994;81:A1128)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1981 1992

Epid

Spi

GA


Changes in obstetric anesthesia(C/S) in UK(Brown et al.Int J.Obstet.Anesth.1995;4:214)

0%

20%

40%

60%

80%

100%

1982 1987 1992

Epid

Spi

GA


Report on Confidential enquiries into maternal deaths in England and Wales

1970-1996

0

5

10

15

20

25

30

1970-72

73-75

76-78

79-81

82-84

85-87

88-90

91-93

94-96

Frequenza per milione di gravid.stimate

emb.polmipertens

anestemb.fluido amniotico

abortogravid.ectopica

emorragiasepsi

rottura uteroaltre cause dirette

Entrata in vigore della nuova classificazione


Tsen LC, Camann W (2000) Training in obstetric general anaesthesia: a vanishing art?

Anaesthesia. 55:179-83


Cameron CB, Gregory GA, Rudolph AM, Heymann M: The cardiovascular and metabolic effects of halothane in normoxic and hypoxic newborn

lambs. ANESTHESIOLOGY 62:732-7, 1985

Oxygen consumption, cardiac output, and tissue oxygen delivery were measured in normoxic and hypoxic 1-3-day-old lambs during the following six conditions: 1) (control) paralysis with pancuronium and controlled ventilation with room air; 2) paralysis, controlled ventilation and hypoxia (PaO2 = 30 +/- 3 mmHg, [SD]); 3) paralysis, controlled ventilation with room air and 0.5 MAC halothane; 4) paralysis, controlled ventilation, hypoxia, and 0.5 MAC halothane; 5) paralysis, controlled ventilation with room air, and 1 MAC halothane; and 6) paralysis, controlled ventilation, hypoxia, and 1 MAC halothane. During normoxia, 0.5 and 1 MAC halothane decreased total body oxygen consumption, cardiac output, and arterial blood pressure. One-half MAC halothane had no effect on blood flow to any organ except muscle, whose flow decreased 64%. One MAC halothane decreased blood flow to the brain, heart, kidney, muscle, and gut. Both concentrations of halothane decreased serum catecholamine levels below control values and prevented hypoxia from increasing catecholamine levels. Hypoxia decreased the oxygen consumption about 40% from the immediately previous normoxic value, whether the animals were anesthetized or not. Tissue oxygen delivery followed changes in blood flow. The cardiac output, arterial blood pressure, and heart rate of anesthetized, hypoxic animals were not different from those in the previous normoxic condition. Halothane did not prevent redistribution of blood flow to the heart and brain of hypoxic animals, nor did halothane prevent hypoxic pulmonary vasoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS).


Effects of halothane anesthesia 0.5 & 1 Mac in normoxic and hypoxic lambs (Cameron et al. The cardiovascular and metabolic effects of halothane in

normoxic and hypoxic newborn lambs. ANESTHESIOLOGY 62:732-7, 1985)

-100-50

050

100150200250300

mean % change

from control

hypoxi

a

hypoxi

a0.

5mac

hypoxi

a1

mac

norm

oxi

a0.

5mac

norm

oxi

a1

mac

O2 consCOHRMPAPPVRlactic acidNorepiEpiSVR


Morti materne associate con l’anestesia in milioni di gravidanze stimate per England &

Wales

0

5

10

15

20

25

30

35

40

70-72

73-75

76-78

79-81

82-84

85-87

88-90

91-93

94-96

97-99

morti associatedirettamentefreq.per milione

% delle morti dirette


Maternal deaths UK 1994-96

thrombosisPIHearly pregnhaemorrhageAFEAnaesthesiaothers


Maternal deaths UK 1997-99

thrombosisPIHafehaemorrhagesuicidesepsis


New trends in UK maternal mortality

Mort.rate among most disadvantaged groups;20 *

Other than white :*2 Young<18 Increasing maternal age Increasing parity Obese In vitro fertilization


Relative risk

C/S 4,9> vag(C/S is an amalgamation of risk associated with the disorder for which surgery is indicated and the risk associated with the procedure itself….

Elective C/S 2.3 Emergent C/S 12.0 Instrum,vag delivery risk 3,1 vs vag deliv


Maternal deaths due to anesthesia:CEMD

02

46

810

1214

1618

20

direct GA indirect

85-8788-9091-9394-96


Panchal et al.Maternal mortality during hospital admission for delivery:a

retrospective analysis using a state maintained

database.Anesth.Analg.2001;93:134-41.

Jan 1984-dec 1997 Maryland DRG C/S and vag.deliv,hospital

only,anonymous Selected case controls 822.591 admissions for delivery 135 deaths Maternal deaths/100.000 5.92-29,6


RISK factors(/100.000)(from Panchal et al)

Age;from 13,9<34 to 23,9>34 Caucasion 7,6,african.americans 31,6,18,1 others African americans 5 times more prob to die during pregnancy

than caucasian Social,cultural,economic,health care access,quality

factors;multiple diagnoses and severity of illness ++ C/S 5,3 +;60% of deaths associated with C/S Minor teaching hospital 3,.1 + Transfer from another hospital 6,2+


Maryland more common causes of maternal mortality

precl/eclamppostpartum hemorrhpulm Kocvs eventAFE/clotinsuff prenatal caretrauma


MARYLAND STATISTICS on Maternal deaths;african american vs caucasian

0

5

10

15

20

25

30

precl/eclamp pulm Ko AFE/clot AC.RENAL FAIL

african-americancaucasian


Number of deaths during cesarean sectionNumber of deaths during cesarean sectionUSA 1979-1990(Hawkins et al.Anesthesiology 86;280:1997)USA 1979-1990(Hawkins et al.Anesthesiology 86;280:1997)

1979-19841979-19841985-19901985-1990

GAGA 3333 3232

REGREG 1919 99




per million of Ga or REGper million of Ga or REG

1979-19841979-19841985-19901985-1990

G.A.G.A. 2020 32.332.3

REGREG 8.68.6 1.91.9


Halper,SH et al.Effect of epidural vs parenteral opioid analgesia on the progress

of labor.JAMA 1998;280:2105-2110

Metanalysis “epidural analgesia has a favourable

effect on funic pH and BE suggesting that the known reduction in maternal stress and sympathetic tone do improve the intrauterine environment ,despite the theorethical potential adverse effects…”


Decision-delivery interval

The 30 min.rule Is this a standard that fetal distress

cases be delivered within 30 min? Fetal hypoxia=scalp pH <7,2;serious

disability when pH<7.00 Correlation between DD interval and

neonatal asphyxia?


DD interval….

C/S ;DD interval shorter with GA(DD 23),but umb.cord artery pH better with reg(DD 50).

Br Med J 322,June 2001 McKenzie1334-35


Reliability.CSE *C/S

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

%

failure rate

QCH 1998Norris 1994Paech 1998Albright 1999


GA is not the choice for obs emergencies

necessary only for true emergencies Necessary only when:

» poor teamwork,poor communication,lack of reg skills

Necessary only for some fetal conditions(tocolysis) GA risk in pregnancy greater GA not necessarily faster and faster my not be

better……….– Crowhurst,2001


Riley ET,Cohen, Sheila E,Macario A,Desai JB,Ratner E.Spinal Versus Epidural Anesthesia for Cesarean Section: A

Comparison of Time efficiency,Costs,Charges and Complications

.Anesth Analg 1995; 80:709–12 Retrospective study from their cases C/S elective epidural (n = 47) or spinal (n = 47) anesthesia Patients who received epidural anesthesia had significantly longer total

operating room (OR) times than those who received spinal anesthesia (101 ± 20 vs 83 ± 16 min, [mean ± SD] P < 0.001); this was caused by longer times spent in the OR until surgical incision (46 ± 11 vs 29 ± 6 min, P < 0.001). Length of time spent in the postanesthesia recovery unit was similar in both groups. Supplemental intraoperative intravenous (IV) analgesics and anxiolytics were required more often in the epidural group (38%) than in the spinal group (17%) (P < 0.05). Complications were noted in six patients with epidural anesthesia and none with spinal anesthesia (P < 0.05). Average per-patient charges were more for the epidural group than for the spinal group. Although direct cost differences between the groups were negligible, there were more substantial indirect costs differences. We conclude that spinal block may provide better and more cost effective anesthesia for uncomplicated, elective cesarean sections.


Spinal faster than epid….( Riley et al, Spinal Versus Epidural Anesthesia for Cesarean Section: A

Comparison of Time Efficiency, Costs, Charges, and Complications.Anesth Analg 1995; 80:709–12)

0

20

40

60

80

100

120

min

OR-incis total OR time Pacu time

epidspi


Drug(opioids,anxyolitics) consumption;spinal vs peridural (Riley et al, Spinal

Versus Epidural Anesthesia for Cesarean Section: A Comparison of Time Efficiency, Costs, Charges, and Complications.Anesth Analg 1995; 80:709–12)

0

5

10

15

20

25

30

35

40

%

intraop postop KO

epidspi

*

I catete intravasc1 catet intratecale1 perf dura3 insuff analg

*


Direct costs($):Spi vs epid

0

5

10

15

20

25

30

35

40

45

spi epid

kitneedledrugmorphfentnurses 13 mintot


Epid takes longer…….. Learning curve the anesthesiologist must progress more slowly with the

epidural needle to avoid a dural puncture the epidural catheter must be threaded and taped a test dose must be given and the patient .observed for 3–5

min to exclude IV or intrathecal placement the entire local anesthetic dose must be administered

incremental onset of epidural anesthesia is slower than that of spinal

anesthesia.


Anesth prep time differed among groups( Glosten et al.Practical aspects of regional anesthesia for

cesarean delivery,failure rates and anesthetic preparation times-An observational study..Anesthesiology 1995;83:A977. ):

0

10

20

30

40

50

60

70

%

failure rate anest prep time anest successful anest unsuccess

GAEPISPIMin


Attitude in failed epidurals(Glosten et al.Practical aspects of regional anesthesia for cesarean delivery,failure rates and anesthetic preparation times-An observational study..Anesthesiology

1995;83:A977. ):

ab sen t b lock 5 in ad eq b lock 1 2 ca te t m isp lac 2 (iv.) p a res tes ia 1 su b d u ra l 2 p a tien t an xie ty 1

ep id fa ilu res(2 4 /1 7 9 )

Repeat EPI 4SPI 11AG 9


Attitude in failed spinalsGlosten et al.Practical aspects of regional anesthesia for cesarean delivery,failure rates and anesthetic

preparation times-An observational study..Anesthesiology 1995;83:A977. ):

in ab ility to ob ta in C S F in traop p a in

S p i fa ilu res(3 /9 8 )

GA


USA changes in anesthesia for C/S( Hawkins et al,Obstetric anesthesia workforce survey-1992 versus 1981.Anesthesiology

1994;81:A1128)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1981 1992

EpidSpiGA


UK changes in obs.anesthesia(Brown et al.Int J.Obstet.Anesth.1995;4:214)

0%

20%

40%

60%

80%

100%

1982 1987 1992

EpidSpiGA


Ben David B,Miller G,Gavriel R,Gurevitch A.Low dose bupivacaine-fentanyl spinal anesthesia for cesarean delivery, Reg

Anest PainMed.2000;25:235-39.

32 paz,20-40 anni isobaric bupi 0.5% 10 mg vs 5 mg+fent 25

microgr preload RL 500;intraop altri 800 ml sitting,26 g pencil point;2 ml in 10-15 sec. Poi supine + LLT efedrina 5-10 mg as needed tempo oper(dal’inizio della spi);<70 min

tutti,eccetto 1.


Ben David et al.Low dose bupivacaine-fentanyl spinal anesthesia for cesarean

delivery, Reg Anest PainMed.2000;25:235-39.

0

10

20

30

40

50

60

70

80

90

100

min,%,mg

time to peakblock

misur ipotens nausea/vomito

bupi 10 mgbupi 5 + fent 25 mu

0.01

0.001

0.00020.0002

Liv medio T3

Liv medio T4-5

0.05

Meno blocco motorio


Vercauteren MP,Coppejans HC,Hoffmann VH,Mertens E,Adriaensen A.Prevention of hypotension by a single 5

mg dose of ephedrine during small dose spinal anesthesia in prehydrated cesarean delivery patients.AA

2000;90:324-327.

Cimetidine p.o 900 mg 1 h prima della induzione RL 1000 ml iniziato 10’ prima del trasferimento in S.OP HES 6% 500 ml all’arrivo in sala op Induzione di CSE dec,.lat dx bupi 6,6 mg+sufent 3.3 microgr intratecale inserito catet pd doppio cieco efedr 5 mg vs placebo dec lat sn 15 O2 3lt/min per masch facciale


Steer, Phyllis L., MD*; Biddle, Chuck J., PhD*; Marley, Wanda S., CRNA MS*†; Lantz, Robert K., PhD‡; Sulik, Patricia L., PhD‡

From the Departments of Anesthesiology at University of Kansas,* Kansas City, Kansas, and Poudre Valley

Hospital,† Ft. Collins, Colorado, Rocky Mountain Instrumental Laboratories, Inc.,‡ Fort Collins, Colorado. Research conducted at the Poudre Valley Hospital, Ft. Collins, Colorado. Address correspondence to: Dr. Phyllis L. Steer, University of Kansas Medical Center, 39th and Rainbow,

Kansas City, Kansas 66103. Funded by the School of Allied Health, University of Kansas and Janssen Pharmaceutica. Accepted for publication 25th November, 1991. ABSTRACT: The purpose of this study was to measure the concentration of fentanyl in human colostrum

after intravenous administration of an analgesic dose. Thirteen healthy women were given fentanyl 2 mg kg-1 for analgesic supplementation during either Caesarean section or postpartum tubal ligation. Serum and colostrum were collected for 45 min, two, four, six, eight, and ten hours following administration of the drug. Radioimmunoassay showed that colostrum fentanyl concentrations were greatest at 45 min, the initial sampling time, reaching 0.40 ± 0.059 ng ml-1, but were virtually undetectable ten hours later. Fentanyl concentrations were always higher in colostrum than in serum. This concluded that with these small concentrations and fentanyl's low oral bioavailability, intravenous fentanyl analgesia may be used safely in breast-feeding women.



Vercauteren et al Prevention of hypotension by a single 5 mg dose of ephedrine during small dose spinal anesthesia

in prehydrated cesarean delivery patients.AA 2000;90:324-327.Results

0

10

20

30

40

50

60

70

80

altra efedr ipotens<90 vomito

efedr 5 mgplacebo

Livello T3 1 per ogni gruppo lidoc 2% 3 ml* p.d.


Coagulation and anesthesia

The Effect of Anesthetic Techniques on Blood Coagulability in Parturients as Measured by Thromboelastography

Sharma, Shiv K., MD, FRCA; Philip, John, MD : Anesthetic techniques may affect blood coagulability and the subsequent incidence of thromboembolic events.

The purpose of this study was to evaluate the effect of spinal and general anesthesia on blood coagulability in normal pregnant women undergoing cesarean section, using thromboelastography. In the spinal anesthesia group (n = 15), thromboelastography was performed after crystalloid preloading and during the immediate postanesthesia course. In the general anesthesia group (n = 15), thromboelastography was performed before induction and during the immediate postanesthesia course. Values for all thromboelastographic variables (reaction time [r], clot formation time [K], coagulation time [rK], maximum amplitude [MA], elastic shear modulus [G], clot formation rate [a angle], and coagulation index [CI]) in the preanesthesia period were similar in both the spinal and general anesthesia groups. However, in the postanesthesia period, r and K significantly decreased (P < 0.05), and a angle (P < 0.05) and CI significantly increased (P < 0.01) in the general anesthesia group when compared with the spinal anesthesia group. In the postanesthesia period, MA and G were similar in both groups. In the spinal anesthesia group, thromboelastographic variables did not change significantly in the postanesthesia compared with the preanesthesia period. We conclude that the use of general anesthesia for cesarean section is associated with accelerated coagulability when compared with spinal anesthesia.

Anesth Analg 1997; 85:82–


Minimizzazione dell’anestesia materna(‘40-’60)

“awareness”


Senza danno per il neonato:

Moir,DD.Anesthesia for caesarean section:an evaluation of a method using low concentration of halothane and 50% oxygen.Br.J.Anaesth.1970;43:136-42.

Halothane 0.5%


“Fetal distress” The term fetal distress is imprecise,non specific and

has little positive predictive value(ACOG Committee Opinion:

Anesthesia for emergency deliveries. Number 104. March 1992) definizione:

» progressive fetal asphyxia that, if not corrected or circumvented will result in decompensation of the physiologic responses (primarily redistribution ofblood flow to preserve oxygenation of vital organs) and cause permanent and central nervous system damage and other damage or death.”(Parer JT, Livingston EG: What is fetal distress? Am J Obstet Gynecol 162:1421, 1990)


Scelta dell’anestesia per il parto cesareo di urgenza-

emergenza

– In the obstetric and anesthetic management of emergent abdominal deliveries, "the maternal as well as fetal status must be considered .. The risk of general anesthesia must be weighed against the benerit for those patients who have a greater potential for complications... Cesarean deliveries which are performed for non‑reassuring FHR patterns do not necessarily preclude the use of regional anesthesia.”(ACOG Committee Opinion:

Anesthesia for emergency deliveries. Number 104. March 1992)


Domande:

Potete ottenere una spinale nel + breve tempo possibile?


Siete sempre in grado di garantire una spinale

rapida?

S p in a le rap id a

ok n on ok

B u p i sem p lice

S i

p rob lem i d i io t

A G

N O


AG per il distress fetale

Ket> TPS nel modello sperimentaleLevinson G, Shnider SM, Gildea E, deLorimier M: Maternal and foetal cardiovascular changes and during ketamine anesthesia in pregnant ewes. Br J Anaesth 45:1111,1973:Pickering BG, Palahniuk RJ, Cote J, et al: Cerebral vascular responses to ketamine and thiopentone during foetal acidosis. Can.Anaesth Soc J 29:463, 1982

ma…..evidenza clinica=,senza contare le CI alla ket(preeclampsia,cocaine abuse….)


Deterioramento fetale(Goodman J, Godewen J, Chance G eds. Fetal acid‑base physiology and fetal asphyxia.

In Perinatal Medicine, Baltimore,Williams and Wilkins, 1977, p. 201)

Cessazione di GC fetale adeguata (p.es FHR< 90,prolasso del cordone)

ogni min pH 0.03-0.04 u. pCO2 3-4 mmHg BE interst 0.80.


Il significato di emergenza

Diverso fra: anestesista ostetrico nurse paziente pediatra avvocato……o magistrato………….


Sequenza temporale i 2-5 min spesi dall’anestesista non

corrisponderebbero forse… alla modificazione della situazione ostetrica

determinata da una più precoce decisione di operare….

Al miglioramento della condizione materno-fetale:» dec lat» ossigenazione» espansione volemia» tocolisi


Conclusioni dai dati di mortalità-morbilità

Non sarà che la mortalità -morbilità materna(e fetale) è più legata all’emergenza-urgenza che all’elezione?


Indicazioni per C/S urgente Materne:

» peggioramento acuto di malattia preesistente

» emorragia massiva» trauma» arresto cardiaco(TC

perimortem)

Fetali:» parte fetale prolassata:

– cordone,– estremità(fallita estraz podalica,fallita estraz di

testa con distocia di spalla…)

» compromissione della circolazione centrale:

– deceleraz tardive non riflesse,senza variabilità,– bradicardia prolungata

– acidemia fetale..

» Danno fetale– da trauma uterino,chiuso o penetrante– emorragia indotta dalla cordocentesi


1992 ACOG Committee Opinion on Anesthesia for emergency deliveries

The entire obstetric care team should be alert to the parturient at increased risk from complications from emergency general or regional anesthesia. When risk factors are identified, an anesthesiologist should be consulted in the antepartum period to allow for joint development of a plan of management.


Ngan Kee WD, Khaw KS, Ng FF. Comparison of

phenylephrine infusion regimens for maintaining maternal blood pressure

during spinal anaesthesia for Caesarean section. Br J

Anaesth 2004; 92:469-74.

Editorial AUTHOR(S): Riley, E. T. My prediction is that within the next few years we will be treating hypotension after spinal anaesthesia in a fundamentally different way than we have during the last 20 years. We will no longer use ephedrine as the mainstay of treatment, we will be more aggressive about

maintaining arterial pressure near normal, and we will worry less (if at all) about the liberal use of other vasoconstricting drugs. In another important contribution by this group, Ngan Kee and colleagues provide evidence that will help us determine the optimal way for preventing the detrimental effects of maternal hypotension after induction of spinal anaesthesia for Caesarean delivery. In this study, the authors maintained maternal arterial pressure at 80%, 90% or 100% of baseline. Using umbilical artery pH as their primary outcome, they found that maintaining the arterial pressure at 100% of baseline was associated with the best outcome for the baby (highest umbilical artery pH) and the mother (less nausea).

Although it is not surprising that maintaining homeostasis is the best strategy, this study shatters the long-held notion that it is best to minimize the use of vasopressors in pregnant patients. It has long been held that vasoconstriction from predominantly alpha-adrenergic agonist drugs will decrease uterine blood flow (UBF) and be harmful to the fetus. Maintenance of low placental vascular resistance and thus better UBF was considered more important than any adverse effects resulting from a 20–30% decrease in maternal arterial pressure.

How did the notion develop that it is better to let the arterial pressure drift down rather than risk placental vasoconstriction? Several sheep studies showed that large doses of vasoconstricting drugs decreased UBF. However, ephedrine maintained UBF much better than other pressors that are primarily vasoconstrictors and have little beta-agonist effect (e.g. phenylephrine and metaraminol). Therefore, ephedrine became the 'gold standard' for prophylaxis and treatment of spinal hypotension.

Accumulating evidence that doses of ephedrine large enough to maintain homeostasis after the induction of spinal anaesthesia may be detrimental to the fetus are causing a major change in our approach to this problem. In a recent study, Cooper and colleagues compared ephedrine and phenylephrine for the treatment of maternal hypotension. Consistent with other recent studies, they found ephedrine caused more acidosis in the fetus. A unique aspect of Cooper and colleagues' study is their evaluation of the degree of acidosis seen in the umbilical vessels. They calculated the difference between the PCO2 in the umbilical artery and umbilical vein (PCO2 (art-vein)). If the PCO2 (art-vein) is small, this indicates poor placental perfusion or gas exchange. For example, conditions such as placental abruption have a small PCO2 (art-vein). If the PCO2 (art-vein) is large, this suggests that acidosis in the umbilical artery is secondary to a process in the fetus. Cooper and colleagues found a strong correlation between ephedrine use and an increase in the PCO2 (art-vein). From these data they concluded that ephedrine was stressing the fetus and may have contributed to fetal acidosis.

There is additional evidence that ephedrine may adversely affect the fetus. When ephedrine was given to women in labour, there were changes in the fetal heart rate pattern (tachycardia and abnormal increases in variability) that might indicate fetal stress or an increase in fetal metabolic activity. These changes were dose related.

Other commonly used vasopressors do not have as much beta-agonist activity and thus do not increase metabolism in the fetus. For example, Cooper and colleagues found no correlation between phenylephrine dose and an increase in the PCO2 (art-vein). The current study, as well as others by Cooper and colleagues and Mercier and colleagues, all reported use of large doses of phenylephrine given to maintain a baseline arterial pressure without any adverse effect on the fetus.

Why do these large doses of phenylephrine (sometimes over 1000 mg total dose) not cause clinically significant vasoconstriction and decreased placental perfusion? Although these large doses were needed to maintain homeostasis, they did not increase arterial pressure to supranormal levels. Therefore, these doses should be considered appropriate for correcting the vasodilatation secondary to a spinal anaesthetic.

The parturient's decreased sensitivity to sympathomimetics during pregnancy may help protect the fetus from excessive vasoconstriction. Tong and Eisenach demonstrated that uterine arteries from pregnant ewes were less responsive to vasoconstrictors compared with those from non-pregnant ewes. Giving large doses of alpha-agonists that constrict peripheral arteries and restore normal maternal arterial pressure may preferentially shunt blood to the uterine arteries, which may be relatively spared from the vasoconstrictive effect.

We must also consider the possibility that significant placental vasoconstriction does occur with phenylephrine, but may not be important with regard to fetal wellbeing. Of particular interest in Ngan Kee and colleagues' article in the current issue is the trend for an increase in umbilical artery PO2 to occur in conjunction with higher maternal arterial pressures (although this did not quite reach statistical significance - P=0.058). This finding is consistent with my observations during ex utero intrapartum therapy procedures and fetal surgery. In these cases, the fetus is at least partially extracted from the uterus but not separated from the placenta. The fetus continues to be supported by the placenta while a procedure is performed. In all instances, a pulse oximeter probe was placed on the fetus. In these cases (performed under general anaesthesia with high-dose potent inhalational anaesthetics given to provide uterine relaxation), I have observed an increase in fetal oxygen saturation of 10–20% when maternal arterial pressure was increased after administration of a vasopressor (ephedrine or phenylephrine) to the mother. Why should maintaining a higher arterial pressure increase oxygen delivery across the placenta? It may be simply that a higher perfusion pressure delivers more blood to the placenta and that this favourable effect far outweighs any variations in placental vascular diameter resulting from the doses of pressors used in recent clinical studies.

Although the current study demonstrates that maintaining a higher arterial pressure increases the umbilical artery pH, is the difference of 0.02 clinically significant? Perhaps not in the healthy fetus. However, there will be cases in which compromised fetuses may benefit significantly by having maternal arterial pressure maintained and fetal oxygen delivery optimized. For example, Datta and Brown showed that umbilical artery pH was only slightly decreased after Caesarean delivery in healthy mothers who experienced transient hypotension secondary to their spinal anaesthetic. However, in infants of diabetic mothers who developed similar degrees of hypotension, the umbilical artery pH decreased to a clinically significant level. Since we do not always know the adequacy of placental reserve, it makes sense to always maintain the arterial pressure near to normal values, given the data presented in Ngan Kee and colleagues' paper.

While it may appear logical to assume that what constitutes good therapy for normal mothers and fetuses constitutes good therapy for the compromised maternal—fetal unit, this may not always be the case. In reality, we do not really know how findings in normal subjects transfer to unhealthy mothers or fetuses. For example, what is the optimal maternal arterial pressure for a pre-eclamptic patient? In a recent study, Dyer and colleagues found that among patients with severe pre-eclampsia, the outcome for the baby was better if the mother had a general anaesthetic rather than a spinal anaesthetic. The spinal anaesthetic group received more ephedrine and presumably suffered from a greater incidence of hypotension compared with the general anaesthetic group. Would the outcome have favoured spinal anaesthesia had that group's arterial pressure been managed more aggressively with phenylephrine? The paper by Ngan Kee and colleagues does not answer this question, but important studies usually create more questions than they answer. Numerous studies have now demonstrated the superiority of phenylephrine for management of spinal hypotension in healthy mothers and babies. We now need more studies on the effects of hypotension and vasoconstrictors in situations of maternal or fetal compromise.

Although there is much more to learn about hypotension and spinal anaesthesia for Caesarean delivery, we already have a wealth of information to help guide therapy. How should we prevent and treat the hypotension associated with spinal anaesthesia? The following are my recommendations:

Leg wrapping. A recent meta-analysis showed that wrapping the legs with elastic bandages or the use of thromboembolic stockings prevents hypotension. Colloid preload. The same meta-analysis found that colloid preloads prevented hypotension and the individual studies found improvements in outcome measures such as Apgar scores, ephedrine use, lower maternal heart rate, less nausea and less severe hypotension.

Crystalloid preloads are largely ineffective. Eliminate or drastically limit the use of ephedrine. Every study that has compared ephedrine and phenylephrine has found more acidosis in the fetus when the mother was given ephedrine. Although it makes theoretical sense to restore both beta- and alpha-adrenergic tone after

the induction of a high sympathectomy from spinal anaesthesia, limit the use of ephedrine. For anaesthetists who are concerned with the possible bradycardia associated with a high spinal or the reflex bradycardia associated with the use of vasoconstricting drugs such as phenylephrine, the use of a mixture of ephedrine and phenylephrine will keep the heart rate up and the dose of ephedrine low enough not to be detrimental to the fetus.

Treat the hypotension aggressively. To reiterate what I said earlier, the use of ephedrine leads to acidosis in the fetus. The aggressive use of phenylephrine and other pure alpha-vasoconstrictors is apparently the best practice. At least, that is what the data provided by Ngan Kee and colleagues suggest.

The data in the literature support the above practices. Now what are needed are studies that evaluate how these changes in management affect outcomes. With the new management strategies, will the umbilical artery pH in babies delivered to mothers having spinal anaesthesia be as good as the values of the mothers having epidural or general anaesthesia? Can we decrease adverse neurological outcomes? Will there be fewer neonatal intubations or admissions to the neonatal intensive care units? Are these the optimal strategies for the compromised maternal—fetal unit? Hopefully, Ngan Kee and colleagues will continue their excellent work and help us answer some of these questions.

E. T. Riley Associate Professor Department of Anesthesia Stanford University School of Medicine Stanford California 94305 USA E-mail: [email protected]

References:


Database dei “Closed claims”(richieste di risarcimento) per l’ awareness intraop

79 / 4183 claims;1.9% :» 18 richieste per awake paralysis(paralisi da svegli)

paralisi involontaria di un paz cosciente

» 61 richieste per ricordi durante GA :ricordo di eventi in corso di GA


Awareness claims

1.9% of all claims awareness, defined as being paralyzed while

awake or awake while receiving a general anesthetic, were reviewed. These claims were further divided into two categories: awake paralysis, i.e., the inadvertent paralysis of an awake patient, and recall during general anesthesia, i.e., patient recalled events while receiving general anesthesia.


Closed claim database for intraoperative awareness

The majority of awareness claims involved :» women (77%)(OR 3.21)» younger than 60 yr of age (89%)» ASA I—II (68%)» who underwent elective surgery (87%),obs/gynecol.

Claims for recall during general anesthesia were more likely to involve :» women (odds ratio [OR] = 3.08, 95% confidence interval [CI] = 1.58, 6.06)

anesthetic techniques using intraoperative opioids (OR = 2.12, 95% CI = 1.20, 3.74)

intraoperative muscle relaxants (OR = 2.28, 95% CI = 1.22, 4.25)

and no volatile anesthetic (OR = 3.20, 95% CI = 1.88, 5.46).


Ranta S, Laurila R,Saario J,Ali-Melkkilä T, Hynynen M. Awareness with Recall During General Anesthesia: Incidence and Risk Factors Anesth

Analg 1998; 86:1084 4818 operations under GA: 2612 (54%) patients were

interviewed 10 (0.4% of those interviewed) patients were found to have

undisputed awareness 9 (0.3%) patients with possible awareness. The doses of isoflurane (P < 0.01) and propofol (P < 0.05)

were smaller in patients with awareness. 5 patients with awareness underwent a psychiatric

evaluation;possible association with depression. 1 patient experienced sleep disturbances afterward, but the

other four patients did not have any after effects.


Approfondimenti sugli effetti degli anest.volatili sul feto ( e

neonato subito dopo la nascita)


Dwyer, R.; Fee, J. P. H.; Moore, J.Uptake of halothane and isoflurane by mother and baby during cesarean section.BJA 1995;74:279

: Twenty–three patients undergoing Caesarean section received either 0.5% halothane or 0.8% isoflurane to supplement nitrous oxide–oxygen anaesthesia. We studied the rate of uptake of the agents by the mother and fetus by measuring partial pressures in maternal arterial (Pa) and fetal umbilical venous (Puv) blood. Mean induction– delivery interval did not differ between the halothane (10.8 min) and isoflurane (11.7 min) groups. There were no differences in maternal heart rate, arterial pressure, pH and blood–gas tensions and fetal pH, blood–gas tensions or Apgar scores between the two groups. Isoflurane uptake by the mother was more rapid than halothane; at delivery, mean Pa of isoflurane as a fraction of the inspired partial pressure (PI) was 0.44 compared with 0.35 for halothane (P < 0.05). Mean Puv as a fraction of maternal Pa at delivery was 0.71 for both agents; thus placental transfer was the same for both agents. Consequently mean Puv/PI was greater for isoflurane (0.32) than halothane (0.26) (P < 0.05). We conclude that both halothane and isoflurane are suitable agents for general anaesthesia for Caesarean section. The rate of uptake of isoflurane by the mother during Caesarean section was more rapid than halothane. The rate of uptake by the fetus from the mother was the same for halothane and isoflurane, so that fetal partial pressure as a fraction of the inspired partial pressure was greater for isoflurane than halothane.


rate of uptake of halothane and isoflurane by the mother and fetus by measuring partial pressures in maternal arterial (Pa) and fetal umbilical venous (Puv) blood



Wojtczak, Jacek A. The Hemodynamic Effects of Halothane and Isoflurane in Chick Embryo Anesth

Analg 2000; 90:1331

The cardiovascular effects of volatile anesthetics in prenatal hearts are not well investigated. The purpose of this study was to determine whether the embryonic cardiovascular system is sensitive to an exposure to clinically relevant, equipotent concentrations of halothane and isoflurane. Stage 24 (4-day-old) chick embryos were exposed to 0.09 and 0.16 mM of halothane and 0.17 and 0.29 mM of isoflurane. Dorsal aortic blood velocity was measured with a pulsed-Doppler velocity meter. Halothane, but not isoflurane, caused a significant decrease in cardiac stroke volume and maximum acceleration of blood (dV/dtmax), an index of cardiac performance. This effect was reversible, and during washout, stroke volume and dV/dtmax increased above control levels. Embryonic heart rate was not affected by either drug. Chick and human embryos are similar during early stages of development; therefore, chick embryo may be a useful model to study the cardiovascular effects of anesthetics.


Effect of halothane on stroke volume and acceleration of aortic blood in

chick embryos


Effect of isoflurane on stroke volume and acceleration of aortic blood in

chick embryos


Biehl DR, Tweed A, Cote J, et al. Effect of halothane on cardiac output and regional flow in

the fetal lamb in utero. Anesth Analg 1983; 62:489-92

We studied the effect of halothane on the fetal cardiovascular system of six lambs in utero by measuring fetal heart rate and femoral arterial blood pressure and by injecting labeled microspheres during a control period and again after 60 and 90 min of halothane anesthesia administered to six pregnant ewes at an inspired concentration of 1.5%. There were no significant effects on maternal cardiovascular function or acid-base balance, but fetal blood pressure decreased significantly by 27% after 8 min of halothane anesthesia and remained at this level for the duration of the experiment. However, there were no significant changes either in fetal regional blood flow to the vital organs or in fetal cardiac output. Fetal oxygenation and acid-base status remained stable. We conclude that in normal fetal lamb in utero the decrease in mean fetal arterial blood pressure associated with maternal halothane anesthesia is due to a decrease in peripheral vascular resistance because regional blood flow and acid-base status are well maintained.


Biehl et al. Effect of halothane on cardiac output and regional flow in

the fetal lamb in utero. Anesth Analg 1983; 62:489-92

-40

-30

-20

-10

0

10

20

30

% change from control

8 16 32 60 96

min

MAPHRheart BFbrain BF

Halothane 1.5%

* * * * *


Bachman CR, Biehl DR, Sitar D, et al. Isoflurane potency and cardiovascular effects during short exposure in foetal lamb. Can Anesth Soc J 1986;

33:41-7 Isoflurane is a relatively new volatile anaesthetic in clinical practice and increasing use

for obstetrical patients might be expected. A previous study demonstrated that a 60-90 minute exposure of the foetus to isoflurane resulted in a significant fall in foetal cardiac output with development of foetal acidosis. To determine the cardiovascular effects of a shorter exposure of the foetal lamb to isoflurane and the potency (MAC) of isoflurane in the foetus, the following study was done. Eleven pregnant ewes were surgically prepared by placing indwelling arterial and venous catheters into the mother and foetus. After a 48-hour recovery period, isoflurane, 2% in oxygen, was administered to six ewes via a tracheostomy for 30 minutes. Foetal cardiac outputs and regional blood flows were measured by the microsphere method. In five ewes the concentration of isoflurane was varied and MAC determinations were done on both ewe and foetus. Arterial blood levels of isoflurane were used to determine foetal MAC. Exposure to isoflurane resulted in a significant decrease in maternal and foetal mean arterial blood pressures and in foetal heart rate. Exposures up to 30 minutes did not result in foetal acidosis or a significant fall in cardiac output. Maternal and foetal MAC for isoflurane were determined to be 0.86 and 0.34 per cent respectively.


Baum VC, Palmisano BW. The immature heart and anesthesia. Anesthesiology 1997; 87:1529-48

volatile anesthetics inhibit myocardial function by depressing systems in addition to ICa,L even in neonatal myocardium. Baum and Wetzel showed that halothane, in clinically relevant concentrations, reversibly inhibits Na+—Ca2+ exchange in neonatal ventricular myocytes. This provides an additional mechanism that may be responsible for the more pronounced depression by volatile anesthetics of immature myocardium with its increased reliance on Na+—Ca2+ exchange.


Baum VC, Palmisano BW. The immature heart and anesthesia. Anesthesiology 1997; 87:1529-48

Halothane and isoflurane prolong AV conduction time directly.,anesthesia and O2 Consumption and Metabolism

In vitro, halothane and isoflurane increase coronary flow in a dose-related manner in infant rabbit and fetal lamb hearts. In the isolated heart preparation in which coronary perfusion pressure is constant, an increase in flow indicates a decrease in coronary vascular resistance and therefore direct vasodilatory actions of the agents on the coronary vessels. Changes in coronary flow are similar between newborn and adult hearts. Other in vitro studies have reported an increase in coronary flow by isoflurane and variable effects by halothane in adult animals. Reactivity of coronary vessels to other pharmacologic and metabolic stimuli have been demonstrated in newborn animals of several species.


Isoflurane decreases O2 consumption and the O2 extraction ratio, which, coupled with increased coronary flow, indicates decreased autoregulation and relative overperfusion of the myocardium, demonstrable in newborn and adult hearts. Because it decreases heart rate more in adults, isoflurane decreases O2 consumption and extraction more in adults than in newborns. When heart rate is held constant by pacing, there are no differences in this effect between age groups.


Baum VC, Palmisano BW. The immature heart and anesthesia.

Anesthesiology 1997; 87:1529-48

In the neonatal lamb undergoing hypoxic stress, neither halothane nor isoflurane alter redistribution of blood to vital organs, including the heart. In addition, myocardial blood flow in the neonatal lamb decreases significantly at 1 MAC isoflurane (from 250 to 88 ml×100 g-1×min-1), but in exact proportion to the decrease in myocardial oxygen consumption, allowing unchanged myocardial oxygen extraction and similar endocardial-to-epicardial myocardial flow ratios.




In neonatal rabbit hearts studied in vitro with 1.5% halothane, McAuliffe and Hickey found no change in steady-state levels of high- energy phosphates or intracellular pH, despite a 50% decrement in mechanical performance. Significant uncoupling of oxidative phosphorylation cannot account for halothane's depressant effect on systolic function in the neonate.




Anesthesia and Systolic Function The effects of the inhalational anesthetics in intact immature hearts

have been evaluated in several studies. Although one study suggested that the apparent increase in hemodynamic depression in the young heart in human studies may be a result of differences in anesthetic uptake and distribution, other studies indicate the increased hemodynamic impairment of the volatile anesthetics is predominantly a result of increased direct myocardial depression in immature hearts. Cook et al., for example, showed that immature (aged 15 days) rats developed cardiovascular failure at significantly lower myocardial halothane concentrations than did older rats.


Volatile anesthetics depress contractility primarily by limiting Ca2+ availability to the contractile apparatus. They alter transsarcolemma and sarcoplasmic reticulum Ca2+ flux with the net result that intracellular Ca2+ stores are depleted. Halothane depresses contractility more than isoflurane. It decreases peak intracellular Ca2+ concentration more than isoflurane, which may be a result of its greater depressant effect on sarcoplasmic reticulum function or on other mechanisms. In isolated rabbit hearts, halothane is a more potent depressant of contractile function (measured by peak systolic and developed LV pressures and +dP/dtMAX) than isoflurane in newborns and in adults. With isoflurane, there are no differential effects between age groups, whereas halothane causes greater depression in neonatal hearts. Other studies in rabbits have also found more depression by halothane of tension development in isolated RV tissue in newborns than adults and more inhibition of RV ventricular papillary muscle contractile function by halothane and isoflurane. In this case, inhibition was similar for both anesthetics. Other investigators have found an age differential in depression of contractility by isoflurane in isolated right atrial tissues of rat, but this may not be comparable with rabbit ventricle. This differential age effect may occur at many sites in the excitation—contraction mechanism, but little information regarding this is available.

Several studies in the chronic neonatal lamb preparation have shown that halothane and isoflurane decrease cardiac output to a similar extent as oxygen consumption. Isoflurane at 1 MAC primarily decreased blood pressure by decreasing cardiac output rather than decreasing systemic vascular resistance. With hypoxemic stress, the isoflurane anesthetized lamb (1 MAC) responds by increasing cardiac output and oxygen delivery.




Summary Immature hearts are more profoundly affected by many

anesthetics than are adult hearts. Maturational changes in a variety of cellular and subcellular systems and influences of the autonomic nervous system may be responsible, but as yet, specific mechanisms remain to be elucidated. Studies of the interactions of anesthetics with the immature human heart are for the most part lacking, and extrapolation from other species is difficult. This is a fertile area for investigation, particularly for studies of the effects of the newer clinical anesthetics, which are lacking.


Brett CM, Teitel DF, Heymann MA, Rudolph AM: The young lamb can increase cardiovascular performance during isoflurane anesthesia.

ANESTHESIOLOGY 71:751-6, 1989 Cardiac output and myocardial blood flow decrease dramatically in a

dose-dependent pattern in the young lamb during isoflurane anesthesia. This raises important questions about the ability of the young lamb to increase myocardial performance if oxygen delivery were compromised by a decrease in oxygen content during anesthesia and surgery. To investigate the ability of the young lamb to increase oxygen delivery during isoflurane anesthesia, the response to hypoxemia, which is known to increase myocardial performance, was studied in awake 1-week-old lambs. Mean systemic arterial pressure, heart rate, cardiac output, and regional distribution of blood flow were measured during three states: awake, 1.0 minimum alveolar concentration (MAC) of isoflurane in an FIO2 of 1.0, and 1.0 MAC of isoflurane in an FIO2 of 0.09. Stroke volume, total body and myocardial oxygen consumption, and fractional extraction of oxygen were calculated for the total body and for the myocardium.


Isoflurane anesthesia decreased mean systemic arterial pressure (70 +/- 8 mmHg), heart rate (222 +/- 29 beats/min), and cardiac output (277 +/- 72 ml.kg-1.min-1) significantly (43 +/- 11 mmHg, 163 +/- 20 beats/min, 191 +/- 34 ml.kg-1.min-1). Hypoxemia returned heart rate to control (191 +/- 23 beats/min), increased stroke volume (1.71 +/- 0.2 ml/kg) above both control (1.23 +/- 0.2 ml/kg) and 1.0 MAC isoflurane levels (1.19 +/- 0.3 ml/kg), and increased cardiac output (325 +/- 61 ml.kg-1.min-1) above the level during 1.0 MAC isoflurane.


“Progesterone Decreases the MAC of Desflurane in the Non Pregnant Ewe,” was presented by Thompson and collaborators, Ochsner Clinic, New Orleans. They noted that the minimum alveolar concentration for pregnant ewes and that for nonpregnant ewes treated with progesterone were similar. The minimum alveolar concentration of desflurane in untreated nonpregnant ewes was greater than in the other two groups.


WarrenTJ,Datta S,Osrheimer GW et al. Comparison of the maternal and neonatal effects of halothane,enflurane and isoflurane for cesarean delivery.Anesth.Analg 1983;62:516-520.


Datta et al.Maternal and fetal catecholamines and uterine incision-delivery interval during

elective cesarean section.Obstet.Gynecol 1990;75:600-603.


Neurobehavioral examination

Results more depressed(albeit subtle) in neonates born from GA than reg….(Shnider 238 pagg…)


Wallace DH et al.Randomized comparison of regional and general anesthesia for cesarean delivery in pregnancies complicated by severe

preeclampsia.Obstet Gynecol 1995;86,193-


Aggiunte sulla AG in ostetr

Claudio MelloniAnestesia e Rianimazione

Ospedale degli InfermiFaenza(RA)


Hawkins JL,Gibbs CP, Orleans M,Martin-Salvaj G, Beaty B. Obstetric Anesthesia Work Force Survey, 1981 versus 1992.SPECIAL ARTICLE.Anesthesiology 87:135-43, 1997

ABSTRACT: Background: In 1981, with support from the American Society of Anesthesiologists and the American College of

Obstetricians and Gynecologists, anesthesia and obstetric providers were surveyed to identify the personnel and methods used to provide obstetric anesthesia in the United States. The survey was expanded and repeated in 1992 with support from the same organizations.

Methods: Comments and questions from the American Society of Anesthesiologists Committee on Obstetrical Anesthesia and the American College of Obstetricians and Gynecologists Committee on Obstetric Practice were added to the original survey instrument to include newer issues while allowing comparison with data from 1981. Using the American Hospital Association registry of hospitals, hospitals were differentiated by number of births per year (stratum I, ³1,500 births; stratum II, 500—1,499 births; stratum III, <500 births) and by U.S. census region. A stratified random sample of hospitals was selected. Two copies of the survey were sent to the administrator of each hospital, one for the chief of obstetrics and one for the chief of anesthesiology.

Results: Compared with 1981 data, there was an overall reduction in the number of hospitals providing obstetric care (from 4,163 to 3,545), with the decrease occurring in the smallest units (56% of stratum III hospitals in 1981 compared with 45% in 1992). More women received some type of labor analgesia, and there was a 100% increase in the use of epidural analgesia. However, regional analgesia was unavailable in 20% of the smallest hospitals. Spinal analgesia for labor was used in 4% of parturients. In 1981, obstetricians provided 30% of epidural analgesia for labor; they provided only 2% in 1992. Regional anesthesia was used for 78—85% (depending on strata) of patients undergoing cesarean section, resulting in a marked decrease in the use of general anesthesia. Anesthesia for cesarean section was provided by nurse anesthetists without the medical direction of an anesthesiologist in only 4% of stratum I hospitals but in 59% of stratum III hospitals. Anesthesia personnel provided neonatal resuscitation in 10% of cesarean deliveries compared with 23% in 1981.

Conclusions: Compared with 1981, analgesia is more often used by parturients during labor, and general anesthesia is used less often in patients having cesarean section deliveries. In the smallest hospitals, regional analgesia for labor is still unavailable to many parturients, and more than one half of anesthetics for cesarean section are provided by nurse anesthetists without medical direction by an anesthesiologist. Obstetricians are less likely to personally provide epidural analgesia for their patients. Anesthesia personnel are less involved in newborn resuscitation.










Hawkins JL,Gibbs CP, Orleans M,Martin-Salvaj G, Beaty B. Obstetric Anesthesia Work Force Survey, 1981

versus 1992.SPECIAL ARTICLE.Anesthesiology 87:135-43, 1997




Breen TW,McNeil T,Dierenfield L.Obstetric anesthesia practice in Canada. Occasional Survey. Can J

Anesth 2000 / 47 / 1230-1242

Purpose: To describe obstetric anesthesia in Canada as practiced in 1997: to identify

practices at variance with the literature and the opinions of experts: and to identify questions for future research.

Methods: In 1997, a detailed postal questionnaire asking about the practice of obstetric anesthesia was mailed to all 1,539 specialist anesthesiologist members of the Canadian Anaesthetists' Society residing in Canada. Non-responders were mailed a second questionnaire three months later.

Results: There were 865 completed questionnaires returned for analysis (56.2%). Of these, 522 anesthesiologists practiced obstetric anesthesia (60.3%). The data were subdivided into those from anesthesiologists with a full or part-time university based practice (40.1%) and those from a community based practice (59.9%). University based and community-based anesthesiologists have very similar patterns of practice. Specific areas where anesthesia practice was different from current recommendations included: (1) information provided when obtaining consent for labour epidural analgesia, (2) use of opioids and local anesthetics for initiation of epidural analgesia, (3) use of coagulation testing in preeclampsia, (4) the common use of cutting spinal needles, (5) use of neuraxial morphine and nonsteroidal anti-inflammatory agents after Cesarean deliveries, (6) optimal treatment of neuraxial opioid side effects, (7) when to insert an endotracheal tube for general anesthesia after delivery, and (8) withdrawing epidural catheters through epidural needles.

Conclusions: This survey presents reference data on the practice of obstetric anesthesia in Canada in 1997. Anesthesiologists with university affiliation have very similar practices to those without university affiliations.


Oyston J.Obstetrical anaesthesia in Ontario CAN J ANAESTH 1995 / 42: 12 / pp1117-25

The purpose of this study was to determine the availability of regional anaesthesia for Caesarean section, of epidural opioids and patient-controlled analgesia after Caesarean section, and of epidural and other forms of analgesia in labour. A mail survey was sent to the “Head Nurse, Department of Obstetrics” at each of the 142 hospitals in Ontario with designated obstetric beds. Responses were obtained from 100% of hospitals. For Caesarean Section, general anaesthesia was used in all hospitals, and was the only option in seven. Epidural anaesthesia was used in 93% of hospitals, and spinal anaesthesia in 48%. Postoperatively, patient-controlled analgesia was used in 31% of hospitals and spinal opioids in 28%. In 66 hospitals, im or iv opioids were the only types of analgesia available. For analgesia in labour, im or iv opioids were used in 96% of hospitals, nitrous oxide was used in 75%, epidural analgesia in 75%, transcutaneous electrical nerve stimulation in 52% and patient-controlled analgesia in 10%. The overall epidural rate was 38%. Although the average rate in the 73 hospitals with fewer than 500 births per year was only 6%, 14 large hospitals had an epidural rate of 60% or higher. It is concluded that regional techniques for peripartum analgesia have been widely accepted. Analgesia after Caesarean section could be improved. Epidural analgesia should be more widely available, especially in the many small hospitals in Ontario.


Oppioidi pre IOT e per mantenimento



Gin, T, Ngan-Kee, W D,Siu YK,Stuart JC,Tan P, Lam KK.Alfentanil given immediately before induction of general anesthesia for cesarean

section.AA 2000;90:1467.

Opioids are routinely omitted at the induction of general anesthesia for cesarean delivery because of concerns about neonatal respiratory depression. The subsequent unmodified maternal stress response to tracheal intubation reduces placental perfusion. The short-acting opioid alfentanil may afford advantages at the induction, without subsequent neonatal depression. In this double-blinded study of elective cesarean deliveries, 40 patients were allocated randomly to receive either alfentanil 10 mg/kg (n = 18) or placebo (n = 22), 1 min before the induction of anesthesia with thiopental 4 mg/kg and succinylcholine 1.5 mg/kg. Anesthesia was maintained with 50% nitrous oxide, 0.5% isoflurane in oxygen, and atracurium. Neonates were assessed by using Apgar scores, Neurologic and Adaptive Capacity Scores, and umbilical cord blood gas and catecholamine analysis. After intubation, mothers receiving alfentanil had a smaller increase in mean arterial blood pressure, (11 ± 15 vs 31 ± 13 mm Hg, P < 0.001) and lower plasma norepinephrine concentrations, (336 ± 152 vs 486 ± 241 pg/mL, P < 0.05). Neonates in the alfentanil group had greater umbilical arterial oxygen tensions (27.8 ± 7.0 vs 22.6 ± 7.4 mm Hg), slightly reduced Apgar scores (both P < 0.05), but similar Neurologic and Adaptive Capacity Scores. One neonate in the alfentanil group required naloxone. The maternal stress response was attenuated in the alfentanil group but at the cost of early neonatal depression. However, all neonates should be monitored for possible immediate, but transient, respiratory depression.


O'Hare R, McAtamney D,Mirakhur RK, Hughes D, Carabine U.Bolus dose of remifentanil for control of haemodynamic response to tracheal intubation during rapid sequence induction of anesthesia.BJA 1999;82:283.

ABSTRACT: The effect of three bolus doses of remifentanil on the pressor

response to laryngoscopy and tracheal intubation during rapid sequence induction of anaesthesia was assessed in a randomized, double-blind, placebo-controlled study in four groups of 20 patients each. After preoxygenation, anaesthesia was induced with thiopental 5–7 mg kg-1 followed immediately by saline (placebo) or remifentanil 0.5, 1.0 or 1.25 mg kg-1 given as a bolus over 30 s. Cricoid pressure was applied just after loss of consciousness. Succinylcholine 1 mg kg-1 was given for neuromuscular block. Laryngoscopy and tracheal intubation were performed 1 min later. Arterial pressure and heart rate were recorded at intervals until 5 min after intubation. Remifentanil 0.5 microg kg-1 was ineffective in controlling the increase in heart rate and arterial pressure after intubation but the 1.0 and 1.25 microg kg-1 doses were effective in controlling the response. The use of the 1.25 microg kg-1 dose was however, associated with a decrease in systolic arterial pressure to less than 90 mm Hg in seven of 20 patients.


Kan RE,Hughes SC,Rosen MA,Kessin C,Preston PG,Lobo EP.,intravenouis remifentanil:placental

transfer,maternal and neonatal efects.Anesthesiology 1998;88:1467

Background: Remifentanil has not been studied in obstetric patients. This study evaluates the placental

transfer of remifentanil and the neonatal effects when administered as an intravenous infusion. Methods: Nineteen parturients underwent nonemergent cesarean section with epidural anesthesia and

received 0.1 microg×kg-1×min-1 remifentanil intravenously, which was continued until skin closure. Maternal arterial (MA), umbilical arterial (UA), and umbilical venous (UV) blood samples were obtained at delivery for analysis of drug concentrations of remifentanil, its metabolite, and blood gases. Maternal vital signs were monitored continuously, and pain and sedation levels were assessed intermittently. Apgar scores were obtained at 1, 5, 10, and 20 min, and Neonatal and Adaptive Capacity Scores were noted 30 and 60 min after delivery. Parturients and newborns were observed for at least 24 h after surgery for side effects.

Results: The means and SDs of UV:MA and UA:UV ratios for remifentanil were 0.88 ± 0.78 and 0.29 ± 0.07, respectively. Mean clearance was 93 ml×min-1×kg-1. The mean UV:MA and UA:MV ratios for remifentanil acid were 0.56 ± 0.29 and 1.23 ± 0.89, respectively. The mean MA (remifentanil acid):MA (remifentanil) ratio was 2.92 ± 3.65. There were no adverse effects on the neonates, but there was a sedative effect and respiratory depressant effect on the mothers.

Conclusions: Remifentanil crosses the placenta but appears to be rapidly metabolized, redistributed, or both. Maternal sedation and respiratory changes occur, but without adverse neonatal or maternal effects.


Bédard JM, Richardson MG,Wissler RN. General anesthesia with remifentanil for Cesarean section in a parturient with an acoustic neuroma..Can J Anesth 1999 / 46 / 576-580

Purpose: To describe the anesthetic management of a parturient with a large acoustic neuroma undergoing general anesthesia with remifentanil for Cesarean section.

Clinical features: A near-term parturient presented with a large intracranial mass. Cesarean section under general anesthesia was elected one week prior to craniotomy for tumour resection. Remifentanil infusion, 0.2–1.0 mg×kg-1×min-1, was used from induction to emergence of general anesthesia. The neonate was born seven minutes after the remifentanil infusion was started. She had normal umbilical cord pH and her Apgar scores were 7 and 8, at one and five minutes respectively. Although the neonate received supplemental oxygen, she did not require naloxone. Both mother and neonate made an uneventful recovery.

Conclusion: Remifentanil was effective in producing stable hemodynamic conditions, without severe neonatal respiratory depression, during induction and maintenance of general anesthesia for a Cesarean delivery in a parturient with a large intracranial tumour.


Bédard JM, Richardson MG,Wissler RN. General anesthesia with remifentanil for Cesarean section in a

parturient with an acoustic neuroma..Can J Anesth 1999 / 46 / 576-580

Case Report A 30 yr-old G2P1 parturient was investigated for progressive right facial numbness over two months and waning right auditory function over four years. A right

acoustic neuroma was diagnosed at 34 wk gestation. Magnetic resonance imaging (MRI) showed a large mass at the right cerebello-pontine angle (3.8 cm x 3.8 cm x 3.8 cm) with a component involving the internal auditory canal (). The tumour compressed the pons, midbrain and fourth ventricle, which were displaced to the left. There was no evidence of rostral hydrocephalus. The patient denied any neurological symptoms other than the initial complaints, and her neurological examination correlated with her symptoms.

The parturient was scheduled to undergo Cesarean section with general anesthesia, followed a few days later by craniotomy for resection of the tumour. Preanesthetic evaluation revealed an otherwise healthy 73 kg woman with a normal airway and an uncomplicated pregnancy at 36 wk. She received 50 mg ranitidine and 10 mg metoclopramide iv the night before and one hour prior to Cesarean section. In the operation room, the patient was positioned suprine with left uterine displacement and 30° head elevation. Blood pressure was measured directly with a radial artery catheter. Maternal blood pressure and heart rate were 115/68 mmHg and 96 bpm, and fetal heart rate 130 bpm. The patient was preoxygenated for four minutes, after which a remifentanil infusion was started at 1 mg×kg-1×min-1 for two minutes. During the infusion, she was reminded to breathe to lead her to slight hyperventilation. Propofol, 100 mg, was administered iv and the remifentanil infusion was decreased to 0.2 mg×kg-1×min-1. Cricoid pressure was applied, as consciousness was lost. The lungs were ventilated with positive pressure by mask to induce slight hypocapnia and prevent hypoxemia. Succinylcholine, 120 mg, and an additional 50 mg propofol were given iv. A transient episode of mild muscle rigidity was observed after induction. However, succinylcholine had just been administered and the episode resolved very quickly. The trachea was easily intubated. The hemoglobin saturation remained 100% throughout induction. The skin was incised four minutes after induction. Anesthesia was maintained with isoflurane 0.5% (end-expired concentration) in 02 and 0.2–0.3 mg×kg-1×min-1 iv remifentanil. Maternal blood pressure and heart rate remained stable before delivery ranging from 105 to 120 mmHg systolic, 55 to 65 mmHg diastolic and 95 to 100 bpm, except briefly immediately before intubation when her blood pressure was 85/50 mmHg. After the umbilical cord was clamped, 250 mg fentanyl, 30 mg ketorolac and 4 mg ondansetron were administered iv and nitrous oxide 70% was added. After skin closure, but before emergence, bilateral ilioinguinal and iliohypogastric nerve blocks were performed using bupivacaine 0.5% with 5 mg×ml-1 epinephrine, 10 ml on each side. Emergence was uneventful and the trachea was extubated. The patient was painfree, responsive and moving all extremities. Satisfactory post-operative analgesia was achieved via iv patient-controlled analgesia using morphine (total of 20 mg in 24 hr). She experienced no nausea or vomiting during the postoperative period.

Because opioid-induced neonatal respiratory depression was anticipated, a neonatalogist was present at delivery. A 2,970 g female was delivered seven minutes after the remifentanil infusion was initiated. The newborn was crying on the surgical field. Spontaneous ventilation and respiratory efforts were normal without evidence of chest wall retraction or nose flaring. However, because of pale colour, supplemental oxygen was given for two minutes with good response. The arterial umbilical cord pH was 7.28 and the venous umbilical cord pH 7.33. Her Apgar scores were 7 (-2 colour, -1 tone) and 8 (-1 colour, -1 tone), at one and five minutes respectively. She was taken to the neonatal intensive care unit for observation. Although the baby did not display any sign of clinical respiratory distress with a respiratory rate from 28 to 44 per min and had a normal chest x-ray, her initial room air 02 saturation was 85–91%. She was placed in a 40% oxygen tent, but this was discontinued within an hour.

The mother and newborn were discharged home three days later. The mother was readmitted three days after discharge, and underwent uneventful craniotomy with resection of the right acoustic neuroma.


Bédard JM, Richardson MG,Wissler RN. General anesthesia with remifentanil for Cesarean section in a

parturient with an acoustic neuroma..Can J Anesth 1999 / 46 / 576-580

Remifentanil has been reported to be ineffective in providing labour analgesia in four parturients while leading to episodes of hemoglobin desaturation from 88 to 95% in three of the four parturients.b In all four, however, it was discontinued long before delivery. Remifentanil has been administered briefly to a parturient to provide effective analgesia during epidural catheter placement, although five hours before she delivered. Remifentanil infusion and placental transfer have been studied in 17 human parturients, who underwent elective Csarean delivery with epidural anesthesia and had a concomitant iv infusion of remifentanil 0.1 mg×kg-1×min-1 for at least 15 min before delivery. The authors stated they did not observe any neonatal depression, however, three of the 17 newborns had Apgar scores ranging from 4 to 7 at one minute. Criteria for neonatal respiratory depression were not described. Apgar scores at five minutes and neurobehavioral testing at 30 and 60 min were normal. The umbilical venous to maternal arterial remifentanil ratio was 0.88, demonstrating considerable placental transfer. The umbilical arterial to umbilical venous remifentanil ratio was 0.29, suggesting either rapid metabolism or redistribution of the drug in the fetus. The observed umbilical venous to umbilical arterial metabolite ratio of 1.23 suggests the former.


Kan RE.Hughes S,Rosen MA,Kessin C,Preston PG,Lobo EP.Intravenous Remifentanil: Placental Transfer, Maternal and Neonatal Effects.Anesthesiology,98:1467-74, 1998

AUTHOR(S): Background: Remifentanil has not been studied in obstetric patients. This

study evaluates the placental transfer of remifentanil and the neonatal effects when administered as an intravenous infusion.

Methods: Nineteen parturients underwent nonemergent cesarean section with epidural anesthesia and received 0.1 mg×kg-1×min-1 remifentanil intravenously, which was continued until skin closure. Maternal arterial (MA), umbilical arterial (UA), and umbilical venous (UV) blood samples were obtained at delivery for analysis of drug concentrations of remifentanil, its metabolite, and blood gases. Maternal vital signs were monitored continuously, and pain and sedation levels were assessed intermittently. Apgar scores were obtained at 1, 5, 10, and 20 min, and Neonatal and Adaptive Capacity Scores were noted 30 and 60 min after delivery. Parturients and newborns were observed for at least 24 h after surgery for side effects.

Results: The means and SDs of UV:MA and UA:UV ratios for remifentanil were 0.88 ± 0.78 and 0.29 ± 0.07, respectively. Mean clearance was 93 ml×min-1×kg-1. The mean UV:MA and UA:MV ratios for remifentanil acid were 0.56 ± 0.29 and 1.23 ± 0.89, respectively. The mean MA (remifentanil acid):MA (remifentanil) ratio was 2.92 ± 3.65. There were no adverse effects on the neonates, but there was a sedative effect and respiratory depressant effect on the mothers.

Conclusions: Remifentanil crosses the placenta but appears to be rapidly metabolized, redistributed, or both. Maternal sedation and respiratory changes occur, but without adverse neonatal or maternal effects.


Roelants F,De Franceschi E, Veyckemans F,Lavand'homme P.Patientcontrolled intravenous

analgesia usig remifentanil in the parturient.Can.J.Anaesth 2001;48:175

From the Department of Anesthesiology, Université Catholique de Louvain Medical School,

Cliniques Purpose: To show the use of the short acting opioid remifentanil for labour analgesia when epidural analgesia is considered to be contraindicated.

Clinical features: After Ethics Committee approval and informed consent, six patients (36–40 wk gestation), in whom epidural analgesia was considered contraindicated (women refusing regional analgesia, presenting with coagulation or platelet abnormalities or sepsis) benefited from patient-controlled intravenous analgesia (PCIA) with remifentanil. The Abbott Lifecare patient-controlled analgesia (PCA) pump with remifentanil 50 mg×ml-1 was set to deliver remifentanil continuous background infusion of 0.05 mg×kg-1×min-1 and 25 mg boluses with a five minutes lockout period. The PCIA was started when the parturients experienced regular painful contractions (cervical dilatation of at least 4 cm) and stopped just before delivery (cervix fully dilated). Maternal monitoring included non-invasive blood pressure measurements, heart rate, percutaneous arterial oxyhemoglobin saturation and respiratory rate. Percutaneous fetal heart rate was continuously monitored. All patients remained alert or sleepy but easily arousable and were satisfied with their analgesia. No particular side effects have been noticed. Apgar scores were between 6 and 10.

Conclusion: Remifentanil PCIA combining low continuous background infusion and small bolus doses is an alternative when epidural analgesia in labour is contraindicated. Under careful anesthesia monitoring, the technique seems to be safe for both mother and baby, at least when delivery occurs at or near the normal term of pregnancy.


Kan RE.Hughes S,Rosen MA,Kessin C,Preston PG,Lobo EP.Intravenous Remifentanil: Placental

Transfer, Maternal and Neonatal Effects.Anesthesiology,98:1467-74, 1998

…..however, the maternal sedation observed with the dose studied is in contrast to previously published work in nonpregnant patients.

The mean remifentanil UV:MA ratio of 0.88 ± 0.78 in this study suggests a significant degree of placental transfer. Considering the high lipid solubility of remifentanil (octanol—water partition coefficient of 17.9 at a pH of 7.4) and generous placental perfusion, this ratio seems more reasonable than the lower value (approximately 0.20) suggested in animal studies,** and is similar to the UV:MA ratio of sufentanil (0.81), as reported by Loftus et al. after epidural administration for labor.

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