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 microg 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 (chi2=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.