Comparison of the efficacy of epidural morphine given by intermittent injection or continuous infusion for the management of postoperative pain.
OBJECTIVE
To compare the effectiveness and side effects of epidural morphine sulfate (MSO4), delivered by continual infusion or intermittent bolus.


METHODS
Thirty patients undergoing upper abdominal surgery were randomized into two equal groups to receive MSO4 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 end of surgery, followed by injections of 2-5 mg morphine into the epidural catheter on demand. Patients in group 2 received an initial bolus of morphine (0.03 mg/kg) during surgical peritoneal closure and were immediately 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, dependent on side effects. Outcome measurements included pulmonary function studies, arterial blood gases, morphine plasma levels, pain relief scores, global evaluations, and side effects.


RESULTS
No difference existed between groups in forced vital capacity, forced expiratory volume in 1 second, or in arterial blood gas measurements. Side effects were similar in both groups. Respiratory depression was not seen in either 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 morphine levels for group 2 (P < .05).


CONCLUSIONS
Continuous epidural infusion provides better analgesia without increased side effects for postoperative pain when compared with an intermittent (or demand) bolus technique.
Department of Anesthesia, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina.
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Rauck
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Raj
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Knarr
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Denson
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Speight
D000005:Abdomen / Q000601:surgery; D000328:Adult; D000368:Aged; D015360:Analgesia, Epidural; D016058:Analgesia, Patient-Controlled; D001158:Arteries; D002245:Carbon Dioxide / Q000097:blood; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007268:Injections, Epidural; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects / Q000097:blood; D010100:Oxygen / Q000097:blood; D010149:Postoperative Pain / Q000188:drug therapy*; D012129:Respiratory Function Tests
D002245:Carbon Dioxide; D009020:Morphine; D010100:Oxygen