COMPARISON OF THE EFFICACY OF EPIDURAL MORPHINE GIVEN BY INTERMITTENTINJECTION OR CONTINUOUS-INFUSION FOR THE MANAGEMENT OF POSTOPERATIVE PAIN

Background and Objectives. To compare the effectiveness and side effec ts of epidural morphine sulfate (MSO(4)), delivered by continual infus ion or intermittent bolus. Methods. Thirty patients undergoing upper a bdominal surgery were randomized into two equal groups to receive MSO( 4) through a thoracic epidural catheter by one of two methods. Group 1 patients received an initial bolus of morphine (0.07 mg/kg) at the en d of surgery, followed by injections of 2-5 mg morphine into the epidu ral catheter on demand. Patients in group 2 received an initial bolus of morphine (0.03 mg/kg) during surgical peritoneal closure and were i mmediately started on an infusion of 0.01% morphine at 5 mL/hour (0.5 mg/hour). The infusion dose was titrated from 0.2 to 1.0 mg/hour, depe ndent on side effects. Outcome measurements included pulmonary, functi on studies, arterial blood gases, morphine plasma levels, pain relief scores, global evaluations, and side effects. Results. No difference e xisted between groups in forced vital capacity, forced expiratory volu me in 1 second, or in arterial blood gas measurements. Side effects we re similar in both groups. Respiratory depression was not seen in eith er group. Group 2 reported significantly better analgesia than group 1 on postoperative days 1 and 2 (P < .01). Peak plasma morphine levels for group 1 were significantly higher than the steady state plasma mor phine levels for group 2 (P < .05). Conclusions, Continuous epidural i nfusion provides better analgesia without increased side effects for p ostoperative pain when compared with an intermittent (or demand) bolus technique.