Does epidural fentanyl decrease the efficacy of epidural morphine after cesarean delivery?

Earlier studies have suggested that epidural fentanyl improves intraoperative analgesia during cesarean section, but others have suggested that it worsens postoperative analgesia from epidural morphine. The purpose of this study was to determine whether epidural fentanyl given before epidural morphine improves the quality of intraoperative epidural anesthesia without worsening postoperative analgesia provided by epidural morphine. Sixty patients having epidural anesthesia for cesarean delivery were studied. Epidural anesthesia was established using 2% lidocaine with epinephrine 5 micrograms/mL. After delivery, either fentanyl 100 micrograms/10 mL or normal saline-control 10 mL was injected through the epidural catheter in a randomized, double-blind manner. All patients received 3.5 mg of morphine epidurally after uterine repair. After administration of the epidural study drug, there were no significant differences in the pain responses during surgery between the two groups. Patients in the fentanyl group experienced significantly less nausea and vomiting between delivery and the end of surgery than did patients in the normal saline-control group (P = 0.013). Postoperatively, visual analogue scale scores for pain, pruritus, nausea, and sedation were similar at 1, 2, 4, and 8 h in the two groups. We conclude that fentanyl 100 micrograms administered epidurally during cesarean delivery did not improve intraoperative analgesia, but significantly reduced intraoperative nausea and vomiting without diminishing the efficacy of postoperative analgesia provided by epidural morphine.