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Note'. Neuhoff, Burke, and Porreco (1989) found that while indentical numbers of nulliparous women had epidural anesthesia (42%), the cesarean rate for failure to progress among clinic patients was 1.2% versus 20.2% for private patients (abstracted in Chapter 5). This suggests obstetric management plays an important role.
10. Thorp JA Ct al. The effect of continuous epidural analgesia on cesarean section for dystocia in nulliparous women. Am J Obstet Gynecol 1989;161(3):670-675. (initial bolus 0.25%, infusion 0.125%)The authors compared 447 nulliparous women in spontaneous labor who had epidurals with 267 nulliparous women who did not. The epidural was discontinued only for lack of progress in second stage. Oxytocin use with epidural was more likely (73% versus 27%, p <0.05). C-section for dystocia was more common with epidural (10.3% versus 3.8%, p <0.005). Birth weights were greater (p <0.005) in the epidural group; however, removing subjects whose babies weighed more than 4000 g did not decrease the cesarean rate discrepancy ("<0.002), nor did removing six cesarean mothers with abnormal labor patterns prior to the epidural ("<0.005). Oxytocin augmentation was "aggressively used to correct dysfunctional labor" (55.8% overall). The discrepancy in cesarean rates may be larger in hospitals taking a more conservative approach.
11. Philipsen T and Jensen NH. Epidural block or parenteral pethidine as analgesic in labour; a randomized study concerning progress in labour and instrumental deliveries. EurJ Obstet Gynecol Reprod Biol 1989;30:27:33. (0.375%)Women, almost all nulliparas (93%), with no evidence of CPD were randomly as - signed in early labor to either pethidine (a narcotic) (N = 54) or epidural anesthesia (N = 57). So that the epidural could wear off, no top-ups were given after 8 cm dilation. All women were offered a pudendal block if they wished, and most accepted (86% in each group) [a confounding factor because pudendal blocks also interfere with pushing]. Equal numbers had oxytocin (33%).
The instrumental delivery rate was 25% versus 26%. The cesarean rate was 17% versus 11% for the epidural group versus control women (NS). [Surely no significance was achieved because the study too small.] Three times the number of women had cesareans for CPD in the epidural group (15.8% versus 5.5%). [Remember, there was no clinical evidence of CPD.] The authors concluded that epidural anesthesia did not increase the instrumental delivery rate and gave better pain relief. [The authors ignore the tripled cesarean rate for CPD.)
12. Gribble RK and Meier PR. Effect of epidural analgesia on the primary cesarean rate. Obstet Gynecol 1991;78(2):231-234. (infusion 0.125%)No differences were found when primary cesarean rates during the 15 months prior to availability of epidural anesthesia (N = 1298) were compared with the 15 months after its introduction (N = 1084, 48% opted for an epidural). Nor were there changes in cesarean indication. [Half the women did not have an epidural, which may have diluted the effect.] Overall cesarean rates were 9.0% prior to epidural availability versus 8.2% following epidural availability. Nulliparas had a 14.4% cesarean rate for dystocia and a 2.3% cesarean rate for fetal distress prior (16.7% total) and a 14.4% rate for dystocia and a 1.6% rate for fetal distress after (16.0% total). Multiparas had a 2.6% rate for dystocia and a 1.2% rate for fetal distress prior (3.8% total) versus a 1.5% rate for dystocia and a 1.7% rate for fetal distress after (3.2% total).
13. Thorp JA et al. Epidural analgesia and cesarean section for dystocia: risk factors in nulliparas. Am J Perinatol l99l;8(6):402-410. (initial bolus 0.25%, infusion 0.125%) (This is a different population from Abstract 10.)Nulliparas in spontaneous labor at dilation 5 cm or less were grouped as follows:
(1) dilation 1 cm per hour or more, no epidural (N = 117);
(2) dilation 1 cm per hour or more, early epidural (N = 45);
(3) dilation 1 cm per hour or more, late epidural (N = 44);
(4) dilation 1 cm per hour or less, no epidural (N = 89);
(5) dilation 1 cm per hour or less, early epidural (N = 170);
(6) dilation 1 cm per hour or less, late epidural (N = 35).
Active management of labor was used (see Chapter 5). To assess the effect of epidurals on cesareans for dystocia, it is important to exclude multiparas because dystocia is rarely a problem in this group.
Comparing group 4 versus S shows the effect of early epidural on dilating slowly. Group 5 women were more likely to have oxytocin (53% versus 86%, p < 0.0009) and cesareans for dystocia (3.4% versus 20.6%, p < 00006). Excluding macrosomic babies did not reduce the effect on cesarean (2.4% versus 20.9%, p <0.00005), 50 selection bias is unlikely to explain the difference.
Comparing groups 4 and 6 shows the effect of late epidural on dilating slowly. Group 6 women were more likely to have oxytocin (53% versus 60%, NS) and cesareans for dystocia (3.4% versus 11.4%, NS), but comparisons probably did not reach significance because of small group size.
Comparing groups 1 and 2 shows the effect of early epidural on dilating rapidly. Group 2 women were more likely to have oxytocin (20% versus 49%, p <0.0004), but not cesareans (1.7% versus 4.4%, NS). Again, the power of this comparison was low.
Comparing groups 1 and 3 shows the effect of late epidural on dilating rapidly. Group 3 was more likely to have oxytocin (43% versus 20%, p < 0.005) and cesareans for dystocia (1.7% versus 11.4%, p < 0.02).
Comparing all nonepidural (groups 1, 4) with all epidural groups (groups Z 3 5, 6), the authors found that women with epidurals were more likely to have oxytocin 34% versus 71%, p < 0.00001) and cesareans for dystocia (2.4% versus 15.6%, p <0.000001). The cesarean rate for fetal distress in the nonepidural versus the epidural group was 1.9% versus 2.7%. [Epidurals do not protect against fetal distress.] The cesarean rate for dystocia correlated with time of placement of epidural (28% < 3 cm, 16%4cm, 11% >5 cm,p<0.01). Rate of dilation prior to epidural also correlated with cesarean for dystocia (23.3% < 0.33 cm/hr, 11.5% 0.33-0.66 cm/hr, 6.8% > 0.66 cm/hr, p < 0.01). Women with early epidurals were more likely to have OP or OT babies during second stage compared with women with no epidural (21.8% versus 9.0%, p =0.0002) and early epidural (21.8% versus 5.2%, p =0005), but incidence was similar for late epidural (5.2%) and no epidural (9.0%).
14. Thorp JA et al. The effect of intrapartum epidural analgesia on nulliparous labor: a randomized, controlled, prospective trial. Am J Obstet Gynecol 1993;169(4):851-858. (initial bolus 0.25%, infusion 0.125%)Nulliparas in spontaneous labor were randomly assigned to epidural (N = 48) or narcotic (N = 45) analgesia. Cesarean for dystocia was never performed during latent phase and was performed only after oxytocin augmentation and documentation by intrauterine catheter of adequate labor.
Epidurals associated with oxytocin use (26.7% versus 58.3%, p <0.05), OP or OT baby persisting into second stage (4.4% versus 18.8%, p < 0.05) (RR 4.3 CI 1.8-6.8), cesarean rate (2.2% versus 25.0%, p <0.05) (RR 11.4 CI 5.8-16.9), and cesarean for dystocia (2.2% versus 16.7%, p <0.05) (RR 7.6 CI 2.8-12.4). The only woman who had a cesarean (for dystocia) in the nonepidural group was the sole woman who actually had an epidural. The risk of cesarean was 50% if the epidural was placed at 2 cm dilation, 33% if placed at 3 cm, 26% if placed at 4 cm, and nil if placed at 5 cm or more ("<0.05). The cesarean rate for fetal distress for epidural versus nonepidural groups was 0 versus 8.3% (NS). The study was originally to have 100 women per group; however, it was discontinued when a significant increase in cesareans was demonstrated "because it would be unethical to continue randomization." [I wonder if they would have gotten a significant difference in cesareans for fetal distress if they had continued.] Before analgesia, women in both groups rated pain at about 7.8 on a scale of 1 to 10. After analgesia, scores in the narcotic group dropped to about 7 but increased to 9 as labor progressed. Scores in the epidural group dropped to about 2.8 and increased to 5 as labor progressed. [So women with epidurals were not pain free.] "Nulliparous patients who are offered epidural analgesia in labor should be informed that it may increase their risk of cesarean delivery."
COMPLICATIONS
Papers Including Complications in Both Mother and Baby.
15. Abboud TK Ct al. Continuous infusion epidural analgesia in parturients receiving bupivacaine, chloroprocaine, or lidocaine - maternal, fetal, and neonatal effects. Anesth Anaig 1984;63:421-428. (bupivacaine: initial bolus 0.5%; infusion 0.125%)Healthy women in normal labor with continuous epidurals either with bupivacaine (N 23), chloroprocaine (N = 19), or lidocaine (N = 19) were compared. Thirty percent of bupivacaine mothers had cesareans versus 11% of chloroprocaine women versus 5% with lidocaine. All were for failure to progress except one, done for fetal bradycardia. Adding forceps and vacuum extraction deliveries, operative delivery rates were 57% bupivicaine, 15% chloroprocaine, and 16% lidocaine (p <0.02). Sixteen percent of the women developed hypotension in response to the anesthetic; incidence was similar among groups.
Umbilical vein lidocaine levels were approximately half that found in the mother's blood, and bupivacaine levels were one-third the mother's. Bupivacaine was significantly more likely to cause abnormal FHR patterns (43% versus 16% versus 10%, p < 0.05). Behavioral test scores were lowest in the lidocaine babies, and all scores were lower compared with unmedicated babies; however, differences did not reach significance [possibly due to the low numbers of subjects]. The authors attribute the excessive bupivacaine cesarean rate to CPD since six of the seven cesareans were for failure of descent in second stage and the anesthetic was allowed to wear off. [It seems unlikely that 26% (6/23) of the bupivacaine mothers coincidentally had CPD. That the epidural was discontinued is not a convincing rationale. Abstract 3 concluded that discontinuing the epidural may not help.]
16. Corke BC and Spiebuan FJ. Problems associated with epidural anesthesia in obstetrics. Obstet Gynecol 1985;65(6):837-839.When a study that showed lidocaine and mepivacaine caused decreased muscle tone in newborns ("floppy, but alert") these drugs were replaced by bupivacaine and 2-chloroprocaine, although subsequent testing failed to confirm the effect with lidocaine. "This happy situation was rudely interrupted in 1980 by a series of reports of permanent neurologic deficits after the use of 2-chioroprocaine," a problem subsequently discovered to occur with accidental injection of large amounts of any local anesthetic into the subarachnoid space.
17. Nel JT. Clinical effects of epidural block during labour. A prospective study. S Afr Med J 1985;68(6):37l~374. (0.5%)
Bupivacaine caused several deaths from cardiac arrest after accidental intravascular injection, something easy to do in pregnant women because they have "enormously dilated" epidural veins. Bupivacaine is more toxic than other local anesthetics; the margin of safety between the occurrence of relatively harmless seizures and the onset of cardiovascular collapse is much smaller. Also, cardiopulmonary resuscitation is particularly difficult in pregnant women.
Lidocaine, 2-chioroprocaine, and bupivacaine are still used, although the most concentrated solution of bupivacaine was banned. Safety measures are not foolproof. "Only personnel with appropriate skills should be responsible for the management of such blocks so the potential for catastrophes is minimal. Should they occur, the appropriate measures therefore can be undertaken promptly."On a high-risk delivery unit, 62 women, 21 of whom had hypertension, had an epidural after 4 cm dilation. Hypotension (defined as a fall in systolic pressure to below 100 mm Hg) occurred in 32% of the women after administration of the epidural; all were successfully treated, Women with hypertension experienced a greater mean fall in blood pressure, and 17 (81%) of them needed no other antihypertensive treatment during labor.
18. Cheek TG and Gutsche BB. Epidural analgesia for labor and vaginal delivery. Clin Obstet Gynecol 19S7;30(3):515-529.
Of the fetuses, five (9%) showed improved FHR pattern and 16 (27%) worsened. Six (37%) of these 16 cases were associated with maternal hypotension, and four of the six improved when maternal hypotension was corrected. The cesarean rate was (19.4%), none for epidural-related fetal distress. Of women delivering vaginally, 44% had an instrumental delivery. Half of these (54%) were due to inadequate bearing-down efforts. Bladder atony resulted in a 19% catheterization rate. By lowering blood pressure, epidurals benefited hypertensive women but at increased risk of hypotension, which in this group may further reduce already inadequate placental perfusion. [FHR abnormalities were also common (6/21, or 29%), hut with no hypertensive nonepidural control group, conclusions cannot be drawn.]This clinical practice paper champions epidurals yet surrounds them with cautions and precautions:
The person administering the epidural should be skilled in emergency management of the airway and toxic reactions and should have resuscitation equipment and medications on hand. Nursing staff should be sufficient for continuous one-on-one care. An anesthesiologist and obstetrician should be immediately available.
19. Uitvlugt A. Managing complications of epidural analgesia. Internat Anesthes Clin 1990;28(l):lI-16.This detailed commentary on preventing and treating epidural complications stresses the importance of trained personnel, close monitoring of mother and baby, precautionary measures, and because precautions fail, the availability of resuscitation equipment and drugs.
Complications of procedure: Accidental subarachnoid injection causes high spinals; the woman loses the ability to speak, to breathe, and finally consciousness. Accidental intravascular injection causes central nervous system (confusion, muscle twitches, convulsions) and cardiovascular (hypotension, bradycardia, respiratory depression or ar rest) toxicity. Hypotension, "a common effect," causes decreased uterine blood flow and fetal bradycardia. If the dura is punctured by a large-bore needle or catheter, the incidence of spinal headache approaches 50%. Since the catheter can migrate, precautions should he repeated at each top-up. [What about continuous infusions?)
Complications of drugs: In rare cases, anaphylactic shock occurs in reaction to the anesthetic. Lidocaine may accumulate in preterm or distressed fetuses, possibly impairing their ability to adapt to asphyxia. Bupivacaine is more cardiotoxic than lidocaine or chioroprocaine and is more likely to cause cardiac arrest if injected vascularly. With bupivacaine, the patient may not be able to be resuscitated. Chloroprocaine should be given "only after a test dose with another agent shows unequivocally that the catheter is not in the intrathecal space [because it does permanent nerve damage]." Epinephrine can cause hypotension, which decreases placental blood flow. Epinephrine should be avoided in preeclamptic or eclamptic patients because they are especially sensitive to catecholamines. The addition of narcotics causes itching or nausea and vomiting in 10% to 30% of patients and can cause respiratory depression or even arrest.
Nerve injury: The needle or catheter may injure a nerve. Recovery may take as long as 12 weeks. Most neurologic problems after the birth (numbness, pain, or muscle weakness in leg or buttock) are due to faulty positioning or forceps trauma. [These occur without epidural anesthesia, but if the mother is not numbed, she would be more likely to shift from an uncomfortable position and less likely to need forceps]. If the mother has a blood-borne infection or is taking anticoagulants, an abscess or hematoma may form. These often do irreversible nerve damage even when promptly recognized and treated.
ORGANIZATION OF ABSTRACTS
Epidurals - Obstetric Myths VS Research Realities... Continued Page 4
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