[The effect of preoperative epidural morphine on postoperative pain].

Postoperative analgesia was assessed by examining nurses' records of 421 gynecological operative cases between January, 1989 and November, 1990. The criterion used in the analysis was the need for analgesics for pain within 24 hours postoperatively. After receiving morphine (2 mg, 4 mg, 5 mg, 6 mg) with local anesthetics or physiological saline solution into the epidural space (lower thoracic, lower lumbar, or both regions), the patient was intubated with thiopental, diazepam, and a muscle relaxant (vecuronium or pancuronium). Anesthesia was maintained with N2O, O2 and vecuronium or a pancuronium supplemented with a low concentration of enflurane or without enflurane. In the control group, anesthesia was maintained with an epidural block with local anesthetics and N2O, O2 supplemented with enflurane or without enflurane. In the groups receiving 2 mg or 4 mg of morphine, the percentage of patients with pain was 69.4+ (34 out of 49 cases) and 54.5% (30 out of 55 cases), respectively. Also, in the groups receiving 5 mg or 6 mg of morphine, the percentage of patients with pain was 39.5% (15 out of 38 cases) and 22.4% (51 out of 224 cases), respectively. In the control group, (with no epidural morphine) 89.1% (49 out of 55 cases) required analgesics. The percentage of patients without pain was significantly larger in the group receiving 6 mg of morphine even in comparison with the groups receiving lesser doses. No serious complications occurred postoperatively in any group. In conclusion, preoperative morphine administered into the epidural space is effective for postoperative analgesia in gynecological operation, especially when morphine 6 mg was administered in the lower epidural (4 mg) and lower lumbar epidural (2 mg) space.