Continuous epidural administration of midazolam and bupivacaine for postoperative analgesia

Background: Midazolam has been reported to have a spinally mediated analges ic effect. Clinically, single-shot epidural or spinal administration of mid azolam has been shown to have an analgesic effect on perioperative pain. In this study we investigated the analgesic effect of continuous epidural adm inistration of midazolam with bupivacaine on postoperative pain. Methods: Four groups of 20 patients who underwent gastrectomy or cholecyste ctomy were studied. Continuous epidural infusion of bupivacaine 100 mg (Gro up C), bupivacaine 100 mg;midazolam 10 mg (Group M10), or bupivacaine 100 m g;midazolam 20 mg (Group M20) in 40 mi per 12 h was started after surgery u sing the balloon infuser. Group I received intermittent epidural bupivacain e (2.5 mg . ml(-1)) 6 ml every 2 h. When necessary, an indomethacin supposi tory and then a single epidural shot of bupivacaine (2.5 mg ml(-1)) 6 mi wa s administered. Blood pressure, heart rate, respiratory rate, analgesic are a, analgesia score, and sedation score were monitored for 12 h postoperativ ely. Memory and frequencies of supplemental analgesia (indomethacin supposi tories and epidural bupivacaine) were also checked. Results: Group M20 showed a significantly wider area of pinprick analgesia and better analgesia scores than other groups. The need for rescue analgesi cs were significantly less in Group M20. Sedation and amnesia were more pro nounced in Group M20 than the other groups. Conclusion: Adding midazolam (10 to 20 mg per 12 h) to continuous epidural infusion of bupivacaine for postoperative pain can provide a better analges ia, amnesia and sedation than bupivacaine alone.