Abstract
In order to estimate the postoperative requirements of analgesics and respiratory depression by buprenorphine, 451 patients undergoing upper abdominal surgery (group 1, n=185), abdominal hysterectomy (group 2, n=170) and mastectomy, lumber laminectomy and oropharyngolaryngeal surgery (group 3, n=96) were investigated in a prospective randamized study. They recieved buprenorphine 2μg/kg i.v., 3μg/kg i.v. or 2μg/kg epidural injection prior to induction of enflurane anesthesia. The postoperative requests for analgesics and the durations of pain relief were not different between intravenous and epidural injection of buprenorphine in both group 1 and group 2. The mean PaCO2, 150-210min after buprenorphine, was slightly higher in the intravenous injection than in the epidural injection in both groups. In group 3 (2μg/kg i.v. alone) the exellent and long-lasting analgesia was obtained, but PaCO2 more than 50mmHg in four patients were observed in recovery room. Patients with PaCO2 above 50mmHg were not observed in other 2μg/kg groups, but three patients in 3μg/kg i.v. groups. The incidence of nausea and vomiting was not different between i.v. and epidural injection and lower than that of previous reports.
We conclude that epidural administration of buprenorphine is not necessarily superior to intravenous route (2μg/kg) prior to enflurane anesthesia to obtain postoperative pain relief.
