Epidural naloxone reduces intestinal hypomotility but not analgesia of epidural morphine

Purpose: Epidural morphine is associated with decreased bowel motility and increased transit time, Low doses of intravenous naloxone reduce morphine-i nduced pruritus without reversing analgesia, but the effect of epidural nal oxone on bowel motility has not been studied. Therefore we evaluated bowel motility and analgesia when naloxone was co-administered with morphine into the epidural space. Methods: Forty-three patients having combined thoracic epidural and general anesthesia for subtotal gastrectomy were randomly assigned to one of two s tudy groups. All received a bolus dose of 3 mg epidural morphine at the beg inning of surgery, followed by a continuous epidural infusion containing 3 mg morphine in 100 mi bupivacaine 0.125% with either no naloxone (control g roup, n = 18) or a calculated dose of 0.208 mug.kg(-1).hr(-1) of naloxone ( experimental group, n = 25) for 48 hr. We measured the time to the first po stoperative passage of flatus and feces to evaluate the restoration of bowe l function, and visual analog scales (VAS) for pain during rest and movemen t. Scores were assessed at 2, 4, 8, 16, 24, 36 and 48 hr postoperatively. Results: The experimental group had a shorter time to the first postoperati ve passage of flatus (51.9 +/- 16.6 hr vs 87.0 +/- 19.5 hr, P < 0.001) and feces (95.3 +/- 25.0 hr vs 132.9 +/- 29.4 hr, P < 0.001). No differences we re found in either resting or active VAS between the two groups. Conclusion: Epidural naloxone reduces epidural morphine-induced intestinal hypomotility without reversing its analgesic effects.