Effect of prophylactic epidural morphine or bupivacaine on postoperative pain after upper abdominal surgery

Morphine 2 mg and 4 mg or bupivacaine 50 mg (another 50 mg 4 h later) was administered into the epidural space prior to general anaesthesia of 40 patients undergoing upper abdominal surgery. During anaesthesia, additional analgesics were not given. In the recovery room (4 h) the pain score (0-10) was lowest in the bupivacaine group (mean 2.4) followed by the 4 mg-morphine group (4.1), 2 mg-morphine group (5.3) and control group (5.7). Half of the patients of the bupivacaine group and those of the 4 mg-morphine group needed no analgesics in the recovery room. Later, in the ward (until next morning 7 am), only morphine patients (5/20) managed without postoperative analgesics. The mean number of requests for analgesics during that time was: 4 mg-morphine 1.3, 2 mg-morphine 1.9, bupivacaine 2.7, and control 2.9. Episodes of hypotension and nausea were most frequent in the bupivacaine group. No serious respiratory complications occurred; 4 h after anaesthesia three patients in the 4 mg-morphine group and two in the bupivacaine group had capillary PCO2 values above 6.65 kPa (50 mmHg), the highest being 7.1 kPa. In two additional patients with choledochal drainage (T-tube), the intracholedochal pressure was shown to rise about 2 kPa 915 mmHg) and 2.7 kPa after epidural injection of 2 mg and 4 mg, respectively. A pressure peak was reached within 10 min and at 75 min the pressure was still 0.7-1.3 kPa above the initial level.