Epidural analgesia and the incidence of cesarean section. Time for a closer look

Early versus late initiation of epidural analgesia in labor: does it increase the risk of cesarean section? A randomized trial

OBJECTIVE

To determine whether early initiation of epidural analgesia in nulliparous women affects the rate of cesarean sections and other obstetric outcome measures.

STUDY DESIGN

A randomized trial in which 449 at term nulliparous women in early labor, at less than 3 cm of cervical dilatation, were assigned to either immediate initiation of epidural analgesia at first request (221 women), or delay of epidural until the cervix dilated to at least 4 cm (228 women).

RESULTS

At initiation of the epidural the mean cervical dilatation was 2.4 cm in the early epidural group and 4.6 cm in the late group (P < 0.0001). The rates of cesarean section were not significantly different between the groups--13% and 11% in the early and late groups, respectively (P = 0.77). The mean duration from randomization to full dilatation was significantly shorter in the early compared to the late epidural group--5.9 hours and 6.6 hours respectively (P = 0.04). When questioned after delivery regarding their next labor, the women indicated a preference for early epidural.

CONCLUSION

Initiation of epidural analgesia in early labor, following the first request for epidural, did not result in increased cesarean deliveries, instrumental vaginal deliveries, and other adverse effects; furthermore, it was associated with shorter duration of the first stage of labor and was clearly preferred by the women.

Effect of Availability of a Parturient-elective Regional Labor Pain Relief Service on the Mode of Delivery

BACKGROUND/PURPOSE

Regional analgesia for labor pain relief is effective and widely used. This study evaluated the controversial association between mode of operative delivery and patient-elective labor regional analgesia.

METHODS

We retrospectively compared the rates of instrumental vaginal and cesarean deliveries in parturients before the introduction, in the first 15 months after, and in the subsequent 36 months after the implementation of an elective labor regional analgesia service. A total of 9779 low-risk singleton cephalic pregnancies above 36 weeks of gestation were included. The maternal and fetal outcomes for parturients before the service was implemented and in those with or without pain relief service in the two postimplementation periods were analyzed. Multivariate logistic regression analyses were used to investigate the effects of maternal age, gestational weeks and newborn weight, in addition to regional analgesia, on the mode of delivery in nulliparous women.

RESULTS

After adjusting for maternal age, gestational weeks, and newborn weight, no significant association was found between regional analgesia and cesarean delivery in nulliparas. Further, this lack of association was not affected by the receipt of regional analgesia in the early period of program implementation or in the period after staff had become familiar with the service. A higher rate of instrumental vaginal delivery was noted in nulliparas given regional analgesia.

CONCLUSION

Regional analgesia for pain relief increased the likelihood of instrumental vaginal delivery, but did not increase the likelihood of cesarean delivery.

A high rate of epidural analgesia with bupivacaine-sufentanil is consistent with a low rate of caesarean section and instrumental deliveries

OBJECTIVE

To prospectively evaluate if a high rate of epidural analgesia (EDA) with bupivacaine-sufentanil is consistent with a low rate of caesarean section, instrumental deliveries and dystocia and to evaluate maternal and fetal adverse effects of sufentanil.

STUDY DESIGN

Populations-based prospective descriptive study. A change of EDA from bupivacaine to low dose bupivacaine-sufentanil at the delivery unit of the hospital during 1993 resulted in a marked increase in the rate of EDA. The outcome from the study period (1994-1995) was compared to the outcome during a reference period 1991-1992.

RESULTS

There were no significant differences in the incidence of caesarean section and instrumental delivery for dystocia between the two periods (4.4 and 4.6%). The overall incidence of caesarean section, 9.6% and instrumental deliveries, 6.4% during the study period was lower than or comparable to the national background data (11.1 and 6.8%, respectively) while the EDA rate was markedly higher 37.8 versus 21.9%.

CONCLUSION

A high rate of EDA, using low dose bupivacaine and sufentanil is consistent with a low rate of caesarean section and instrumental deliveries. No apparent negative effects on the neonates or mothers were observed.

The effects of epidural analgesia on the course and outcome of labour

The potential effects of epidural analgesia on the progress and outcome of labour have been the subject of lasting controversy. Retrospective reviews indicate that epidurals are associated with longer labours and/or an increase in the incidence of instrumental or operative delivery. Similar results were obtained in non-randomized prospective studies. None of them established a causal relationship, because without randomization the selection bias cannot be ruled out. Other factors, such as premature rupture of membranes and maternal socioeconomic status, may affect the outcome of labour. It was also reported that introduction of the on-demand epidural service did not increase the primary caesarean section rate. The few prospective randomized studies are contradictory and not very reliable owing to small patient populations and high cross-over rates. There is, however, unanimity among the authors regarding the superiority of pain relief provided by epidural blocks over systemically administered opioids.

The course of labor with and without epidural analgesia

OBJECTIVE

Our purpose was to measure effects of epidural analgesia on labor compared with boluses of meperidine in a cohort of women with similar clinical circumstances.

STUDY DESIGN

One hundred ninety-nine nulliparous women who were delivered spontaneously at term and who received oxytocin for labor augmentation before the initiation of analgesia were identified for analysis. All these women were managed in a low-risk labor unit according to a standardized protocol. This management protocol encouraged early amniotomy and the use of oxytocin when ineffective labor was diagnosed.

RESULTS

The demographic characteristics of the two study groups were similar with respect to age, height, weight, and maternal age. The two groups had the same cervical dilatation on admission (3.3 cm) and at the time of analgesia administration (4.1 vs 4.2 cm), indicating similar progress of labor before oxytocin administration. The length of the active phase of labor was longer in the epidural group (7.9 vs 6.3 hours, p = 0.005), as was the second stage (60 vs 48 minutes, p = 0.03). The mean and maximal rates of oxytocin infusion were similar between the two study groups; however, the amount of oxytocin required for each centimeter of cervical change was more in the epidural group (22 vs 16 mU per cm of cervical change, p = 0.009). Neonatal outcomes were unaffected by the type of labor analgesia.

CONCLUSION

Epidural analgesia decreases uterine performance during oxytocin-stimulated labor, resulting in an increase in the length of the first and second stages of labor.

Obstetric outcome following epidural analgesia with bupivacaine-adrenaline 0.25% or bupivacaine 0.125% with sufentanil--a prospective randomized controlled study in 1000 parturients

BACKGROUND

Epidural analgesia (EDA) is the most efficient method for pain relief during labour, but there is still a debate as to whether it interferes with the normal process of delivery. Some authors argue that the incidence of instrumental deliveries, Caesarean section, malrotation and protracted labour is increased in parturients receiving EDA.

METHODS

1000 parturients were prospectively randomized to receive EDA either with a high dose of local anaesthetic (0.25% bupivacaine with adrenaline = HD) or with a low dose (0.125% bupivacaine with sufentanil 10 micrograms = LD).

RESULTS

The incidence of instrumental delivery and Caesarean section and the need for oxytocin was reduced in the LD compared to HD group. The delivery time was similar with HD and LD among primiparous, but decreased significantly among multiparous in the LD group. The incidence of malrotation was low in both groups. The quality of analgesia was equal during the first stage in the 2 groups, but was lower in the LD group during the second stage. More parturients in the LD group ambulated, but this did not affect the incidence of instrumental delivery.

CONCLUSION

It is concluded that a lower dosage of bupivacaine combined with sufentanil in epidural analgesia significantly improves the obstetric outcome as compared to a higher dosage of bupivacaine with adrenaline using intermittent bolus technique.

Nulliparous active labor, epidural analgesia, and cesarean delivery for dystocia

OBJECTIVE

Our purpose was to examine the effect of epidural analgesia on dystocia-related cesarean delivery in actively laboring nulliparous women.

STUDY DESIGN

Active labor was confirmed in nulliparous women by uterine contractions, cervical dilatation of 4 cm, effacement of 80%, and fetopelvic engagement. Patients were randomized to one of two groups: epidural analgesia or narcotics. A strict protocol for labor management was in place. Patients recorded the level of pain at randomization and at hourly intervals on a visual analog scale. Elective outlet operative vaginal delivery was permitted.

RESULTS

One hundred women were randomized. No difference in the rate of cesarean delivery for dystocia was noted between the groups (epidural 8%, narcotic 6%; p = 0.71). No significant differences were noted in the lengths of the first (p = 0.54) or second (p = 0.55) stages of labor or in any other time variable. Women with epidural analgesia underwent operative vaginal delivery more frequently (p = 0.004). Pain scores were equivalent at randomization, but large differences existed at each hour thereafter. The number of patients randomized did not achieve prestudy estimates. A planned interim analysis of the results demonstrated that we were unlikely to find a statistically significant difference in cesarean delivery rates in a trial of reasonable duration.

CONCLUSIONS

With strict criteria for the diagnosis of labor and with use of a rigid protocol for labor management, there was no increase in dystocia-related cesarean delivery with epidural analgesia.

The dose-response pharmacology of intrathecal sufentanil in female volunteers

The pharmacologic effects of intrathecal sufentanil (ITS) beyond what is clinically administered (10 microg) are not known. We observed 18 healthy, young, adult female volunteers who received 12.5, 25, or 50 microg of ITS in a randomized, double-blind fashion for 11 h. Analgesia was assessed by pressure algometry at the tibia. Respiratory function was assessed by pulse oximetry, respiratory rate, arterial blood gas, the ventilatory response to CO2, and a respiratory intervention score (RIS). The incidence and severity of side effects also were documented. Serum sufentanil levels were measured for 4 h after ITS administration. We found that ITS produced statistically significant changes in algometry, doubling the pressure required to produce moderate pain. However, doses of ITS greater than 12.5 microg failed to produce proportionate increases in the duration or intensity of analgesia. All doses of ITS produced significant respiratory depression, but only the RIS was significantly related to ITS dose. Neither respiratory rate nor sedation reliably predicted hypoxemia. Supplemental oxygen by nasal cannula consistently prevented pulse oximeter readings below 90%. Serum sufentanil concentrations were related to ITS dose in a statistically significant manner, reached clinically significant concentrations, and followed a time course similar to analgesia and measures of respiratory depression. However, there was no significant increase in measured analgesia associated with the increases in serum sufentanil concentrations. We conclude that in our volunteer model of lower extremity pain, administering ITS in doses larger than 12.5 microg does not improve the speed of onset, magnitude, or duration of analgesia and only causes dose-related increases in serum sufentanil concentrations, which may augment respiratory depression.

Fetal heart rate changes after intrathecal sufentanil or epidural bupivacaine for labor analgesia: incidence and clinical significance

The objective of this study was to compare the incidence of intrapartum fetal heart tracing (FHT) abnormalities and the obstetric outcome after intrathecal sufentanil (ITS) versus epidural bupivacaine (EB). During the period from April to September 1994, 129 patients who met inclusion criteria were prospectively identified during labor at a single university-affiliated hospital. Inclusion criteria included: singleton, gestational age > or = 36 wk, and cephalic presentation. In the ITS group, epidural anesthesia was not administered before 60 min after ITS. Sixty-five consecutive ITS patients were compared to 64 consecutive EB patients. Each FHT was reviewed independently by two obstetricians blinded to the type of analgesia. The FHT characteristics evaluated included baseline rate, variability, and periodic changes. No differences in the incidence of clinically significant FHT abnormalities (recurrent late decelerations and/or bradycardia) were observed between the two groups (ITS 21.5% versus EB 23.4%). The rates of clinically significant FHT abnormalities in both groups was not different when patients with hypotension and medical complications were excluded (16.9% vs 17.1%). In addition, equal rates of hypotension (18.5% vs 17.2%) were noted between the groups. In both groups there was a significantly higher risk of cesarean section in patients whose previously normal FHT became abnormal postanalgesia when compared to patients without a new onset FHT abnormality (ITS 28.6% [4/14] versus 2.0% [1/51], P < 0.01; EB 33.3% [5/15] versus 8.2% [4/49], P < 0.05). This increased risk was associated with an increase in cesarean section for nonreassuring FHT in both groups (ITS 14.3% [2/14] versus 0% [0/51], P = 0.04; EB 13.3% [2/15] versus 0% [0/49], P = 0.05). These results support the conclusion that the incidence of clinically significant FHT abnormalities and hypotension is equivalent in patients receiving ITS when compared to EB within the first hour of administration. During this period, patients should have continuous FHT monitoring since a new onset FHT abnormality unveils and alerts the physicians to a possible compromised fetal condition and a corresponding increased risk of cesarean section.