[Continuous intravenous infusion with patient-controlled anesthesia for postoperative analgesia in cesarean section: morphine versus buprenorphine].

A double blind comparison between morphine and buprenorphine was performed in 20 patients using a new demand and continuous infusion analgesic system to provide analgesia after cesarean section. The patients were randomized in two equal groups to receive either morphine 1 mg/h or buprenorphine 0.03 mg/h. The PCA system was set to deliver bolus of either morphine 1 mg or buprenorphine 0.03 mg, with a lockout interval of 10 and 15 min respectively. A loading dose of morphine 5 mg or buprenorphine 0.15 mg was given if necessary. The quality of analgesia, assessed by a visual analogue and a subjective scale was good with both drugs. No difference in side effects between the groups was observed. The mean potency ratio between buprenorphine and morphine was 32:1. Patients receiving buprenorphine showed a more prolonged analgesia and a significant improvement of sedation score.