Epidural analgesia for labour and delivery: Fentanyl or sufentanil?

Purpose: The highly lipid soluble opioids, fentanyl and sufentanil, are used in combination with local anaesthetics with/without epinephrine to provide epidural analgesia during labour and delivery. Our aim was to determine whether either opioid was superior when used with low dose-local anaesthetic. Methods: In a double-blind study patients were randomized to two epidural infusion groups: Group I (n = 50) fentanyl 2 mu g . ml(-1) with bupivacaine 0.015% and epinephrine 2 mu g . ml(-1), Group II (n = 50) sufentanil 1 mu g . ml(-1) with bupivacaine 0.015% and epinephrine 2 mu g . ml(-1). Following a 20 ml bolus of the study solution an infusion was stalled at 10 ml . h(-1). To achieve analgesia patients could receive two boluses of 5 ml of the study solution and if analgesia was still inadequate, a further 5 ml bupivacaine 0.25% was used. Pain and overall satisfaction were assessed with a 10-point visual scale. Plasma samples obtained from the mother at the time the infusion was discontinued and from the umbilical cord vein at delivery were assayed to determine opioid concentration. Results: Pain scores were greater for Group I than for Group II patients throughout the first and second stages of labour (P = 0.002). More patients in Group I (42%) requested a dose of bupivacaine 0.25% than in Group II (6%) (P < 0.0001) and the total dose of bupivacaine given to Group I patients was greater than that of Group II, 26.0 +/- 22.0 mg vs. 13.4 +/- 12.6 mg, P = 0.005. There were no differences with respect to first or second stage duration, incidence of side effects, infusion duration, outcome of labour or neonatal Apgar scores. There was no opioid accumulation in either maternal or foetal blood. Conclusion: Epidural opioid infusion with very low dose bupivacaine (0.015%) achieved an overall high level of patient satisfaction in both groups without serious maternal or neonatal side effects. At the fentanyl-to-sufentanil ratio used here patients receiving sufentanil had lower pain scores and substantially fewer patients required bupivacaine rescue.