Epidurals and Cesarean Deliveries: A New Look at an Old Problem

A comparison of epidural magnesium and/or morphine with bupivacaine for postoperative analgesia after cesarean section

BACKGROUND

Magnesium can potentiate the antinociceptive effect of morphine. This prospective randomized double-blinded study was undertaken to establish the analgesic effect of adding magnesium to epidural morphine during cesarean section.

METHODS

Two hundred patients undergoing cesarean section under combined spinal-epidural anesthesia were recruited. After administration of intrathecal bupivacaine 10mg, patients were randomly assigned to receive one of four epidural study solutions: 0.1% bupivacaine 10 mL (Group B); 0.1% bupivacaine 10 mL and morphine 1.5mg (Group B+Mor); 0.1% bupivacaine 10 mL and magnesium 500 mg (Group B+Mg); or 0.1% bupivacaine 10 mL morphine 1.5mg and magnesium 500 mg (Group B+Mor+Mg). The primary outcome was the area under the curve for visual analog scale pain scores during 36 h postoperatively. Secondary outcomes included time to the use of rescue analgesics, patient satisfaction and side effects.

RESULTS

Patients in Group B+Mor+Mg had lower for pain scores and area under the curve pain scores both at rest and on movement, increased time for first analgesic request, and increased satisfaction score at 24h after surgery.

CONCLUSION

Addition of magnesium 500 mg and morphine 1.5mg to epidural 0.1% bupivacaine 10 mL reduced postoperative pain compared with addition of morphine or magnesium alone or no additive.

Onset of labor epidural analgesia with ropivacaine and a varying dose of fentanyl: a randomized controlled trial

BACKGROUND

This study was conducted to investigate the onset of labor epidural analgesia using 0.17% ropivacaine with a varying dose of fentanyl. We hypothesized that the onset of analgesia would be shortened in proportion to an increase in fentanyl dose.

METHODS

Women requesting labor epidural analgesia were enrolled in this randomized controlled clinical trial. Each woman was randomly assigned to receive fentanyl 0, 50, 75, or 100 μg with 0.17% ropivacaine 12 mL. The onset and duration of analgesia, the incidence of side effects and patient satisfaction were measured.

RESULTS

Data from 102 women were analyzed. The onset of analgesia (mean ± SD) was shortened with an increasing dose of fentanyl (14.3 ± 5.4, 14.2 ± 6.5, 12.1 ± 5.1, and 8.7 ± 3.8 min with fentanyl 0, 50, 75, or 100 μg, respectively, P=0.001). The duration of analgesia was prolonged with an increasing dose of fentanyl (87.4 ± 20.8, 112.3 ± 19.5, 140.8 ± 18.8, and 143.6 ± 18.6 min with fentanyl 0, 50, 75, or 100 μg, respectively, P<0.001). The incidence of pruritus increased with an increasing dose of fentanyl (P=0.027) but there were no differences for other maternal side effects. There was a significant difference in satisfaction score among groups (P=0.009).

CONCLUSION

The addition of increasing doses of fentanyl to 0.17% ropivacaine contributed to shortened onset as well as prolonged duration of labor epidural analgesia and improved patient satisfaction.

Epidural Infusions of Ropivacaine and Bupivacaine for Labor Analgesia: A Randomized, Double-Blind Study of Obstetric Outcome

Studies have shown better obstetric outcome when ropivacaine 0.25% was used for labor epidural analgesia compared with bupivacaine 0.25%, but it is controversial whether there is any difference at smaller concentrations. In a prospective, double-blind trial, we randomized 350 ASA physical status I and II parturients with term cephalic singleton pregnancies to receive epidural labor analgesia using ropivacaine or bupivacaine. Analgesia was initiated with a 0.25% solution and maintained with a continuous infusion of a 0.1% solution with fentanyl 0.0002%. Supplementary boluses of 0.25% solution were given when requested. Labor was managed according to institutional standard labor ward protocols. Among patients who delivered vaginally, the duration of the first stage of labor was shorter in the ropivacaine group (median, 520 min; interquartile range, 377-745 min) compared with the bupivacaine group (645 min; interquartile range, 460-820 min; P = 0.009), but there was no difference in any other obstetric or neonatal outcomes. The mode of delivery was similar between groups, with operative (instrumental vaginal and cesarean) delivery rates of 61.8% (95% confidence interval, 54.4%-68.8%) in the ropivacaine group and 58.4% (95% confidence interval, 50.9%-65.5%) in the bupivacaine group (P = 0.72).

IMPLICATIONS

In a randomized-controlled study, we found no major outcome advantage of continuous epidural infusion of ropivacaine 0.1% with fentanyl 0.0002% over bupivacaine 0.1% with fentanyl 0.0002% for labor analgesia. Although ropivacaine was associated with a shorter first stage of labor, the relative difference is probably of limited clinical importance, and there was no difference in the mode of delivery.