Comparison of intrathecal fentanyl and bupivacaine in combined spinal-epidural obstetric analgesia

OBJECTIVES: To compare intrathecal injection of the opioid fentanyl to injection of bupivacaine, in terms of their effect of labour in the context within the combined spinal-epidural analgesia. METHODS: Prospective single-blind trial in primiparas randomized to 2 groups for sedation with 25 mu g of fentanyl or 2.5 mg of bupivacaine, followed in both cases by epidural infusion of ropivacaine. We measured time from puncture to delivery of the neonate, rescue analgesia, pain assessed on a visual analog scale (VAS), motor block, side effects, sensory level, Apgar score, and maternal satisfaction. RESULTS: Sixty-four women were studied. The mean time elapsed between puncture and birth was 168.59 minutes (95% confidence interval [CI], 134.16 to 203.03 minutes) in the bupivacaine group and 189.13 minutes (95% CI, 151.93 to 226.32 minutes) in the fentanyl group. The mean difference was -20.53 minutes (95% CI, -70.21 to 29.15 minutes). Survival analysis applied to duration of labor, using type of delivery as the final outcome, also failed to show a significant between-group difference (chi(2)=0.59, P=.447). No significant differences in use of rescue analgesia, VAS scores, or motor block were observed. The incidence of pruritus in the fentanyl group was 34.37%, but there were no differences in maternal satisfaction. CONCLUSIONS: Our findings do not support the use of intradural fentanyl with the aim of shortening labor. Fentanyl leads to more pruritus, although this side effect does not affect maternal satisfaction.