EPIDURAL NALBUPHINE FOR ANALGESIA FOLLOWING CESAREAN DELIVERY - DOSE-RESPONSE AND EFFECT OF LOCAL-ANESTHETIC CHOICE

The analgesic profile of epidural nalbuphine for postoperative pain relief and the impact of local anaesthetic choice upon this profile was investigated in 58 patients undergoing elective Caesarean delivery under epidural anaesthesia. Patients were randomized to receive either lidocaine 2% with 1:200,000 epinephrine or 2-chloroprocaine 3% for perioperative anaesthesia, followed by either 10, 20, or 30 mg of epidural nalbuphine administered at the first complaint of postoperative discomfort. Postoperative analgesia was quantitated on a visual analogue (VAS) scale, and by the time from the epidural opioid injection until the first request for supplemental pain medication. The duration of analgesia after lidocaine anaesthesia followed by 10, 20 or 30 mg nalbuphine was 77 (53-127) min, 205 (110-269) min, and 185 (116-241), respectively (median, 95% confidence interval, P < 0.01, 20 and 30 mg vs 10 mg). Following 2-chloroprocaine anaesthesia, VAS remained consistently elevated: the median duration of analgesia was only 30-40 min and did not differ among the three doses of nalbuphine. Side-effects consisted only of somnolence, and were noted only following lidocaine anaesthesia. Somnolence was observed in 0, 20% and 50% of those receiving 10 mg, 20 mg and 30 mg of nalbuphine respectively (NS). No evidence of respiratory depression was noted in any patient. It is concluded that 20 or 30 mg of epidural nalbuphine provides analgesia for only two to four hours following Caesarean delivery with lidocaine anaesthesia, but anaesthesia with 2-chloroprocaine resulted in minimal or no analgesia from this opioid. Nalbuphine appears to be a disappointing agent for epidural use after Caesarean delivery.