Debate on Labor Analgesia Chan Wei-Hung MD Department of Anesthesiology NTUH

Debate on Labor Analgesia

Chan Wei-Hung MD

Department of Anesthesiology NTUH

Labor Analgesia

About 1/3 nulliparous parturient experience severe, intolerable pain.

Epidural administration of analgesics revolutionized the management of labor pain by eliminating the side effect of parenteral analgesics.

However, there is no single medical intervention without any side effect.

『只聽過麻醉麻死人的，沒聽過產痛會痛死人的。』

Words from some renowned obstetrician

Protagonists of the Debate

James A Thorp -- Department of Obstetrics and Gynecology, St. Luke's Perinatal Center, Kansas City

David H Chestnut -- Department of Anesthesiology,

University of Alabama School of Medicine, Birmingham

The Effect of Intrapartum Epidural Analgesia on Nulliparous Labor: A Randomized, Controlled, Prospective Trial

Thorp, James A.; Hu, Daniel H.; Albin, Rene M.; McNitt, Jay; Meyer, Bruce A.; Cohen, Gary R.; Yeast, John D

American Journal of Obstetrics and Gynecology, 169(4) Oct 1993 , 851-858

Materials and Methods

Narcotic group: 75 mg of meperidine and 25 mg of promethazine IV every 90 min as needed in first stage.

Epidural group: initial bolus of 0.25% bupivacaine followed by a continuous infusion of 0.125% bupivacaine adjusting to a dermatomal level of T10-12 throughout the second stage.

Cesarean section for dystocia was performed only when there was an arrest of cervical dilatation in the active phase of labor or when there was arrest of descent in the second stage of labor.

Conclusions-I

Epidural analgesia in nulliparous labor is associated with significantly longer first and second stages of labor, more frequent use of oxytocin, more frequent incidence of malposition, and significant increase in cesarean section for dystocia.This adverse effect of epidural analgesia on labor and delivery may be limited by delaying the epidural placement to a cervical dilatation of >=5 cm.

Conclusions-II

Epidural analgesia in nulliparous labor provides superior analgesia compared with narcotic analgesia.

Nulliparous patients who are offered epidural analgesia in labor should be informed that it may increase their risk of cesarean delivery.

Does Epidural Analgesia Increase the Incidence of Cesarean Section?

DH ChestnutDH Chestnut

Twelve (25%) of 48 women in the epidural group versus one (2%) of 45 women in the meperidine group underwent cesarean section.

A twelvefold increase in the cesarean section rate in the epidural group is hard to believe.

Maternal request is a sufficient justification for pain relief during labor.

Regrettably, the study by Thorp et al may prompt some obstetricians and third-party payers to restrict access to effective pain relief during labor.

American Journal of Obstetrics and Gynecology 171(5), 1994, 1398

Epidural Analgesia and Frequency of Cesarean Section

No attempt was made to blind the obstetricians

How many patients were invited to participate but declined?

No mention is made regarding the maximum dose used of oxytocin

The effect of epidural analgesia on the mode of delivery depends inextricably on the setting in which it is practiced.


Intrapartum Epidural Analgesia and Nulliparous Labor

When caudal epidural analgesia was introduced in the 1940s, the block was not initiated until the active phase of labor had been reached.

Thus the practice of yesteryear has much to offer.

The epidural block should be initiated with a low concentration of local anesthetic (e.g., 0.0625% bupivacaine) and a small dose of opioid (e.g., fentanyl 2 micrograms/ml).


The Influence of Epidural Analgesia on Labor

We found that epidural analgesia significantly shortens the duration of the first and second stages of labor in singleton vaginal delivery in 1206 parturients (583 nulliparous and 623 multiparous).

I feel that the conclusion offered by Thorp et al, are not entirely substantiated by the literature.


The Peril of Hasty Analysis

The cesarean rate in the epidural arm was only 25%, which would be considered normal or even low in some institutions.

The cesarean rate among the patients who received narcotic analgesia was unusually low (2.2%)

I feel that this study is marred by its statistical technique.


Epidural Analgesia and Frequency of Cesarean Section

I am amazed at the fact that only one of the 45 nulliparous patients in the narcotic group requested epidural analgesia.

Maybe women in Kansas City are tougher than women in Boston.

My experience is that a much higher percentage of nulliparous women will request epidural analgesia.

Some obstetric departments may dissuade patients from receiving epidural analgesia.


Are Today’s Epidurals the 12% Solution?

That Thorp et al.’s 45 nulliparous women receiving intravenous meperidine and promethazine had but one C/S (2.2%) is impressive.

Anesthesiology 82(1), 311-312, 1995

Does Early Administration of Epidural Analgesia Affect Obstetric Outcome in Nulliparous Women Who Are in Spontaneous Labor?

DH Chestnut, JM McGrath, RD Vincent,

DH Penning, WW Choi, JN Bates, C McFarlene

Anesthesiology 80(6), 1201-1208, 1994

Materials and Methods

Early group: boluses of 0.25% bupivacaine by request.

Late group: nalbuphine 10 mg IV boluses by request

After cervical dilatation of 5 cm, both groups started epidural infusion of 0.125% bupivacaine.

The anesthesiologist adjusted the epidural infusion rate to maintain satisfactory analgesia yet minimizing motor block.

Anesthesiology 80(6), 1201-1208, 1994

Early Late

Second Stage (min) 85±65 88±62

Malposition 13% 12%

Instrumental delivery 37% 43%

C/S rate 10% 8%

Prolong Second Stage (>3h)

8% 8%

Anesthesiology 80(6), 1201-1208, 1994

RESULTS

Conclusions

Early administration of epidural analgesia did not prolong labor, increase the incidence of oxytocin augmentation or increase the incidence of operative delivery.

It is unnecessary to await an arbitrary 5 cm cervical dilatation before administration of epidural in nulliparous women who are in spontaneous labor at term.

Anesthesiology 80(6), 1201-1208, 1994

Epidural Analgesia During Labor

RD VINCENT, Jr. and DH CHESTNUT

Induction of epidural analgesia in early labor remains controversial.

Many physicians induce analgesia as soon as the diagnosis of active labor has been established and the patient has requested pain relief.

Recent data do not support the conclusions of earlier studies that administration of epidural block before 5 cm of cervical dilation will adversely affect the subsequent course of labor.

American Family Physician 58(8), 1998, 1785-1792

Epidural Analgesia During Labor

RD VINCENT, Jr. and DH CHESTNUT

Retrospective studies: association between epidural analgesia and increases in duration of labor, instrumental vaginal delivery and cesarean section.

Such studies are biased by the fact that women who progress rapidly through labor often have less pain and are less likely to request regional analgesia.

Several recent prospective studies: epidural analgesia does not adversely affect the progress of labor or increase the rate of cesarean section.


Advantages of Epidural Analgesia

Provides superior pain relief during first and second stages of labor

Facilitates patient cooperation during labor and delivery

Provides anesthesia for episiotomy or forceps delivery

Allows extension of anesthesia for cesarean delivery

Avoids opioid-induced maternal and neonatal respiratory depression


Complications of Epidural Analgesia

Immediate

Hypotension

Urinary retention

Local anesthetic induced convulsions

Local anesthetic induced cardiac arrest

Delayed

Postdural puncture headache

Transient backache

Epidural abscess or meningitis


Controversial Issue

Maintenance of profound epidural analgesia beyond complete cervical dilation will increase the duration of the second stage of labor or increase the probability of an instrumental vaginal delivery--especially in nulliparous patients.


Complications of epidural analgesia during labor – JA Thorp

Vincent and Chestnut would contend that these studies that epidural analgesia increases cesarean delivery are flawed.

I would maintain that St. Luke's Hospital of Kansas City are committed to minimizing rates of intervention.

During the years after our trial, there has been a progressive decline in cesarean delivery in cases of dystocia in nulliparous patients using epidural analgesia.


Complications of epidural analgesia during labor – JA Thorp

Those who conduct formal studies are more apt to limit rates of intervention.

Conclusions drawn from research centers may not necessarily apply to other institutions.

Epidural analgesia did not affect cesarean delivery rates; but it did have significant effects on labor.


Does epidural analgesia prolong labor and increase risk of cesarean delivery? A natural experiment

Zhang, Jun; Yancey, Michael K.; Klebanoff, Mark A.; Schwarz, Jenifer; Schweitzer, Dina

American Journal of Obstetrics and Gynecology

185(1), 2001, 182-134

Results

Epidural rate: 1% to 84%

First stage and active phase: unchanged

Second stage of labor is prolonged. (25 min more in average)


185(1), 2001, 182-134

Conclusions

Epidural analgesia during labor does not increase the risk of cesarean delivery, nor does it necessarily increase oxytocin use or instrumental delivery caused by dystocia.

The duration of the active phase of labor appears unchanged, but the second stage of labor is likely prolon

ged.


185(1), 2001, 182-134

Current Policy In Our Hospital

1. No epidural before cervical dilatation of 4 cm

2. No epidural in the second stage

3. IV hydration before/during epidural

4. Bupivacaine 0.0667% ± fentanyl 1.67μg/ml

5. Infusion rate 8~15 ml/hr ± initial loading 5~10 ml

6. Essentially nurse-control analgesia

THANK YOU

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Debate on Labor Analgesia Chan Wei-Hung MD Department of Anesthesiology NTUH