Analgesia and Anesthesia in Labor and Delivery

8/2/2019 Analgesia and Anesthesia in Labor and Delivery

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ANALGESIA andANESTHESIA in Labor and

Delivery

dr. Adhitya Maharani Devi, M.Kes, SpOG


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Pain Pathways and The Stages ofLabor

The first stage of labor :Begins with the onset of regular contraction and

ends with the cervix being completely dilated

The pain is conducted via the T10 to L1 nerve rootsThe Second stage of labor :

Begins at full cervical dilatation and ends withthe delivery of the infant

The pain caused by distention of the vulvaand perineum, is conducted by the pudendalnervia the S2 to S4 nerve roots


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Three essensial of obstetricalpain relief

Simplicity

Safety

Preservation of fetal homeostatis

The women who is given any form of

analgesia should be monitored closelyRisk vary according to the type ofanalgesia selected


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Anesthetic Risk Factors inPregnant Women

1 Marked obesity2 Severe edema or anatomical anomalies of the face and neck

3 Protuberant teeth, small mandible, or difficulty in opening themouth

4 Short stature, short neck or arthritis of the neck

5 Large thyroid

6 Asthma, chronic pulmonary disease or cardiac disease

7 Bleeding disorders

8 Severe preeclampsia-eclampsia

9 Previous history of anesthetic complication

10 Other significant medical or obstetrical complication


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Pain Relief DuringLabor and Delivery

A. PARENTRAL MEDICATION


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1. SEDATIVE TRANQUILIZERS

Generally used during the first stage labor

Often in conjunction with narcotic

Barbiturates is generally restricted to the early

stage because of depressant effect on theneonate

The phenothiazines, promethazine and

hydroxyne are efeffective in reducing anxietywithout causing neonatal depression


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Diazepam (valium), has been safelyused in small doses to relieve

extreme maternal anxiety without

producing significant adverseneonatal effect

Midazolam also a benzodiazepine,

can cause retrograde amnesia thatis undesirable at the time of birth


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2. NARCOTICUsed to provide pain relief duringlabor and to supplement regional

and general anesthesia during a

cesarean deliverySide effect :

Some degree of respiratory depression

Orthostatic hypotension

Nausea and vomiting

Transferred rapidly across the placenta and

cause neonatal respiratory depression


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Meperidine (Demerol) :

Currently the most commonly used narcotic in obstetric

It has repleassed morphine as an obstetric analgesic,

because of the latters prolonged duration of action andgreater neonatal respiratory depression

Fentanyl :

As adjuvant for both regional and general anesthesia for

cessarian delivery

The use of IV for analgesia during labor is currentlyunder investigation

The synthetic narcotic agonist-antagonist, butophanol and

nalbuphine, cause on limited respiratory depression,makingthem useful for labor analgesia

Side effect :

Dizziness or drowsiness

Unsuitable for ambulating patient


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3. DISSOCIATIVE DRUG ANDNEUROLEPTANALGESIA

DISSOCIATIVE DRUGKetamine and scopolamine

Rarely used as sedative during labor

NEUROLEPTANALGESIAUsing a combination of a narcotic and a majortranquilizer (i,e, fentanyl and droperidol) is not

a popular technique

Potensial for profound neonatal depression


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B. REGIONAL ANALGESIAFOR LABOR AND

DELIVERY1. CLASSIFICATION OF BLOCK


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a. The Lumbar epidural block

The most popular forms of analgesia duringlabor

Can be performed as a single injection (when

the cervix is fully dilated and the fetal head arein position for delivery)

Or as a continuous technique consisting ofintermittent boluses of local anesthesia throughan epidural catheter (usually initiated whencervical dilatation reaches 4 to 6 cm)


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Capable of providing uninterrupted analgesia

throughout labor & deliveryMonitoring maternal BP and FHR

A low concentration of combined localanesthetic & narcotic via continuous infusion

providing a continuous and stable level ofanesthesia with fewer occurences of hipotensiveepisodes while better maintaining pelvic muscletone

An increase in cesarean delivery rates whenepidurals are administered before 5 cm ofdilatation


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b. The Caudal Block

A form of epidural analgesia in which the epidural spaceis entered through the sacral hiatus

Less frequently used for vaginal delivery, because lesseffective in providing analgesia during the first stage oflabor and is more painful to administer.

More local anesthetic agent, thus increasing the risk oftotal spinal anesthesia should dural puncture.

Puncture of the fetal head and injection into the fetusRectal examination should be performed to rule out thispossibility

Perineal anesthesia and muscle relaxation are morerapid


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c. The Subarachnoid (Spinal)Block

Not commonly used for vaginal delivery

Because the urge to bear down isabolished and the mother is unable tocooperate in the delivery.

Excellent anesthesia for cesareandelivery


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d. The Paracervical Block

Used for pain relief during the first stage of labor

Generally performed when the cervix is dilated 4to 6 cm in the multiparous and 5 to 6 cm in

primiparousFetal bradycardia is the most common andserious complication and the incidence may beas high as 50%

Should not be done in the presence of impaireduteroplacental circulation or if the fetus is at risk


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e. The Pudendal Block

For pain relief during the second stage oflabor

Produces adequate perineal analgesia for

outlet forceps delivery as well asepisiotomy and repair

For optimal effect administered at the

start of the second stage of labor in theprimiparous and at 6 to 8 cm dilatation inthe multiparous


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f. The Local Block

Generally used before an episiotomy isdone during vaginal delivery


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EFFECT OF REGIONALANESTHESIA ON LABOR

AND DELIVERY


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Because of the number of variable present inany given delivery The effect of regionalanalgesia on the progress and outcome isdifficult to ascertain.

Epidural analgesia has minimal effect on

duration or quality of the first stage labor ifhypotension is avoided and uterinedisplacement is maintained

Epidural analgesia increased the duration of the

second phase of the labor as well as increasingthe frequency of instrumental delivery


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This effect can be minimized through the

use of more dilute concentration of localanesthetics in combination with low doseof narcotic (fentanyl/sufentanil) using a

continous infusion techniqueThe administration of a perineal dose of

local anesthesia just before delivery result

in an increased of instrumental delivery


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C. INHALATIONANESTHETICS FOR LABOR

AND DELIVERY


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Nitrous oxide (N2O) has been found to have littleeffect on the uterus

The halogenated agent(Halothane,flurane,isoflurane) can produceprofound, dose dependent uterine relaxation

General anesthesia can be used to relax theuterine during tetanic contraction or to facilitateuterine manipulation

Such relaxation can lead to increased blood

loss, this effect can be reversed by theadministration of oxytocin


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D. ANESTHESI FOR

CESAREAN DELIVERY


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1. REGIONAL

Spinal and Epidural anesthesia

The use of RA technique allows for:

A decreased risk of pulmonarya aspiration(compared with GA)

Decreased the risk of neonatal respiratorydepression by lessening the need for

systemic narcoticThe mother is awake and able to participatemay enhance the birth experience


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The disadvantages RA include :The possibilities of a prolonged onset time (compared

with GA)Spinal headache

Maternal hypotension with resulting fetal hypoxia

Contraindication :

Patient RefusalHypovolemic shock

UPI

Septicemia or infection at the site of injection

Coagulation disorders (including HELLP syndromeNeurologic disorders, such as mutiple sclerosis

Preeclampsia maternal hypotension decrease inuteroplacental perfusion and fetal asphyxia.


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Immediate Complication ofEpidural Analgesia

High or total spinal

Hypotention

Urinary retention

Headache

Postdural puncture seizure

MeningitisCardiorespiratory arrest

Vestibulocochlear dysfunction


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2. GENERAL

The major advantage :The Speed in which it can be administretedand in which a distressed fetus can be

deliveredLess maternal hypotension

Has greater cardiac stability and allows forcontrol of the airway and ventilation

Preferable in patient with coagulopathies,preexisting neurologic disease, local infectionor generalized sepsis


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The disadvantage :

Increased posibility of aspiration pneumonitisin the pregnant patient maintenance ofmaternal ventilation and oxygenation andprevention of maternal hypotension

The insidence of difficult or failed intubation ismuch higher in the obstetric surgical patient


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ANESTHETICCONSIDERATION IN THE

PREGNANT PATIENT


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Tetatogenic in human ?? fetal exposure toany drug should be minimized, especially during

the first trimesterElective surgery be postponed until 6 weekspostpartum

If possible, surgery should be postponed until

the second or third trimesterRegional anesthesia technique selected tominimize fetal exposure to drugs

If GA with N2

O is to be employed, considerpretreating with folinic acid because N2Oinactivate vit B12, with is essensial in folatemetabolism and thymidine synthesis


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After the sixteenth w.o.g continuous FHRmonitoring & Uterine contraction to detect

preterm deliveryThe pregnant or postpartum patient has anincreased risk of aspiration of gastric content preoperative administration of antacids,

dopamine agonist (metoclopramide) or H2-receptor antagonist (famotine), Anticholinergics(atropine,scopolamine) has not been shown toeffectively to decrease.

When GA is required, the airways must beprotected via placement of endotracheal tube


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Skill tracheal intubation accompanied bypressure on the cricoid cartilage toocclude the esophagus The Sellick

maneuver.


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LOCAL ANESTHETIC

AGENT


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A.Mechanism of Action

Local anesthetic agents blok the sodiumchannels in the nerve membrans, thusimpairing propagation of the action

potensial in axons

In general, myelinated fibers are morereadily blocked than non myelinated, and

the thinner fibers are more easily blockedthen thick ones


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B. Types of Local Anesthetic

Local anesthetics are classified as :Esters (procain, chloroprocaine, tetracaine)

Amides(bupivacaine,etidocaine,lidocaine,mepivacaine)

The esters are motabolized by plasmacholinesterase and thus have short half-lives incirculation

Paraamino benzoic acid, a degradation productof ester metabolism, can cause ahypersensitivity reaction in susceptibleindividuals

Amide local anesthetics are metabolized

primarily in the liver


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C. Ester Local Anesthetic Agent

Procaine (Novocain) is a short actingagent used for local infiltration and spinalanesthesia

Chloroprocaine (Nesacaine) is a shortacting agent used for local infiltration andepidural anesthesia

Rapid hydrolysis of this agent by plasmacholinesterase makes this the leastcardiotoxic of the local anesthetics


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Arachnoiditis and neurotoxicity with this agentare now attributed to the preservative

metabisulfite, which has been replaced withEDTA

This new formulation cause severe backache

when dosage exceeds 25 ml of solutionChloroprocaine or one of its metabolites canimpair the action of other epidural agents, suchas bupivacain or fentanyl

Tetracaine is along-acting agent used primarilyfor spinal anesthesia


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D. Amide Local AnestheticAgents

Bupivacaine (Marcaine, Sensorcaine) canbe used for all form of local and regionalanesthesia

It provides a sensory block of high quality(in relation to the degree of motorblockade) and long duration

Its slow onset of action (up to 30 minutes)can make it impractical for urgentprocedurs


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Intravascular injection of bupivacaine can resultin cardiac arrest that is resistent to treatment

pregnant patients in labor are more susceptibleto this effect and 0.75% is contraindicated forepidural anesthesia or obstetric practice

Lidocaine (Xylocain) is the most frequently usedlocal anesthetic for all form of local and regionalanesthesia.

Although lidocain does have a high rate of

placental transfer, Apgar scores are statisticallyunaffected.


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Mepivacaine (Carbocaine) is used for

local infiltratration, nerve block andepidural anesthesia with a duration ofaction slightly longer than lidocaine

It has an increased half-life in the neonate,which has lead to a decline in its use inobstetrics.


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COMPLICATIONS OF

REGIONAL ANESTHESIA


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A. HYPOTENSION

The most common complication of spinal orepidural anesthesiaBP must be monitored frequently because evenmild reduction may adversely affect uterine

blood flow.The degree and durationof maternalhypotension necessary to cause fetal distressare variable

Fortunately, if hypotension from RA is promptlycorrected, it has little adverse effect on neonataloutcome


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To prevent maternal hypotension include

hydration before administration of RA andcontinous left uterine displacement tominimize aortocaval compression

Prophylactic of a vasopressor (ephedrine,10 to 15 mg IV) is effective in decreasingthe incidence of maternal hypotensionassociated of spinal anesthesia

Treatment of hypotension after spinal orepidural anesthesia include


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Rapid infusion of fluids

Increasing left uterine displacementAdministration of IV ephedrine

Trendelenburg position to increase

venous return

The administration of supplementaloxygen to the mother will not necessarily

raise fetal PaO2 if maternal hypotension isnot corrected

B TOTAL SPINAL


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B. TOTAL SPINALANESTHESIA

Can result from:

extensive spread of local anestheticadministrated subdurally

Injecting the epidural dose of local anestheticinto an epidural needle or catheter that hasbeen improperly placed or that has migratedinto the subarachnoid space.


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Nausea and profound hypotension may befollowed by loss of consciousness and cardiac orrespiratory arrest

Treatment is supportiveAirway established

Ventilated with oxygen

Trachea intubated (using succinylcholine, 1 to 1.5

mh/kg) to prevent aspiration of gastric contentTrendelenburg position with left uterine displacement

Fluid and ephedrine to maintain BP

Maternal bradycardia must be treated promptly by

administering atropine and ephedrine. If there areineffective, IV epinephrine should be administered

In cases of cardiac arrest secondary to high spinalanesthesia, afull resuscitation dose of epinephrineshould be administered immediatly

C LOCAL ANESTHETIC


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C. LOCAL ANESTHETICCONVULSIONS

High blood level of a local anesthetic maybe a result of accumulation duringrepeated injections or rapid systemic

absorption from a highly vascular areaGenerally caused by the in advertent ivinjectionof local anesthetic during epiduralanesthesia

Seizures are generally preceded by loss ofconsciousness.


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Early recognition of this reaction is important

because small doses of barbiturates (diazepam,5 mg or thiopental 50 mg IV, repeated asnecessary) may prevent convulsion

Treatment is generally supportive with

ventilation and circulation supported.The incidence can be decreased by judiciouslyaspirating needles and catheters before dosingand by routinely injecting test doses of localanesthetic with epinephrine.


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D. NEUROLOGIC COMPLICATIONS

The most common complication of spinaland epidural anesthesia is the postduralpucture (spinal) headache

For a spinal anest. , the incidence can beminimized by using the smallest needleposible,

Prophylactic bed rest and increasedhydration have little or no effect onincidence of postpuncture headache


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The incidence of dural puncture with epidural

anest is ussually between 1% to 2% withheadache occuring almost 80%

Treatment is generally supportive and consistsmainly of bed rest, hydration and use of oral

analgesic.IV caffeine sodium benzoate and oral caffeinehave been shown to relieve these headache

Severe cases might require a blood patch, whichis ussually very effective


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Analgesia and Anesthesia in Labor and Delivery

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