[Is epidural buprenorphine with nitrous oxide-oxygen-enflurane anesthesia indicated for surgery of short-duration?]

The effects of duration of surgeries on epidural buprenorphine (Bn) with nitrous oxide-oxygen enflurane anesthesia were examined. The subjects were 64 patients who underwent upper abdominal surgery. The patients were divided into two groups in terms of the time required for surgery: i.e., group I (surgery of short duration, n = 18) and group II (surgery of long duration, n = 46). They were given 0.2 mg epidural Bn just before induction and then general anesthesia with nitrous oxide-oxygen-enflurane was performed. The patients were rated with intraoperative anesthetic dosage, time required for arousing from anesthesia, postoperative respiratory depression and postoperative analgesia. There was no significant difference between groups I and II with regard to the dose of Bn, maximum concentration of inhaled enflurane and time required for arousal from anesthesia. There were, however, significant differences in postoperative respiratory state between the two groups. The mean tidal volume was 307.6 ml in group I, which is lower than the corresponding value, 429.5 ml in group II (P less than 0.01), and PaCO2 was higher in group I (mean 44.9 mmHg) than in group II (42.3 mmHg) (P less than 0.05). Although no difference was found in the time from Bn administration to the first analgesic supplement between the two groups, the postoperative analgesic time was longer in group I than in group II (P less than 0.05). From these results we conclude that considerable care should be taken for surgery of short duration under epidural buprenorphine with nitrous oxide-oxygen-enflurane anesthesia.