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,

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 T 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.

DH Chestnut Does Epidural Analgesia Increase the Incidence of Cesarean Section? DH 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. American Journal of Obstetrics and Gynecology 171(5), 1994, 1396

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., % bupivacaine) and a small dose of opioid (e.g., fentanyl 2 micrograms/ml). American Journal of Obstetrics and Gynecology 171(5), 1994, 1396

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. American Journal of Obstetrics and Gynecology 171(5), 1994, 1396

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. American Journal of Obstetrics and Gynecology 171(5), 1994, 1397

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. American Journal of Obstetrics and Gynecology 171(5), 1994, 1399

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), , 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), , 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), , 1994

EarlyLate Second Stage (min)85±6588±62 Malposition13%12% Instrumental delivery37%43% C/S rate10%8% Prolong Second Stage (>3h) 8% Anesthesiology 80(6), , 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), , 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,

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. American Family Physician 58(8), 1998,

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 American Family Physician 58(8), 1998,

Complications of Epidural Analgesia Immediate Hypotension Urinary retention Local anesthetic­induced convulsions Local anesthetic­induced cardiac arrest Delayed Postdural puncture headache Transient backache Epidural abscess or meningitis American Family Physician 58(8), 1998,

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. American Family Physician 58(8), 1998,

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. American Family Physician 58(8), 1998,

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. American Family Physician 58(8), 1998,

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,

Results Epidural rate: 1% to 84% First stage and active phase: unchanged Second stage of labor is prolonged. (25 min more in average) American Journal of Obstetrics and Gynecology 185(1), 2001,

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 prolonged. American Journal of Obstetrics and Gynecology 185(1), 2001,

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 % ± fentanyl 1.67μg/ml 5.Infusion rate 8~15 ml/hr ± initial loading 5~10 ml 6.Essentially nurse-control analgesia

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