Effect of subarachnoid morphine administration on extubation time after coronary artery bypass graft surgery

Objective: To determine the effects of 2 low doses of intrathecal morphine on extubation time and on postoperative analgesic requirements after corona ry artery bypass graft (CABG) surgery. Design:A prospective, randomized, double-blind, placebo-controlled study. Setting: Tertiary-cam university hospital. Participants: Fifty adult patients scheduled for elective primary CABG surg ery. Interventions: Patients were randomized to receive placebo, 250 mug, or 500 pg intrathecal morphine, preoperatively. Intraoperative fentanyl and midaz olam were limited to 15 mug/kg and 20 mug/kg intravenously. Patients were e xtubated in the intensive care unit by a blinded observer using predefined extubation criteria. Measurements and Main Results: Time to extubation and postoperative require ments for morphine, midazolam, nitroglycerin, and sodium nitroprusside were recorded by a blinded observer. Extubation times were 441 +/- 207 minutes versus 325 +/- 188 minutes versus 409 +/- 245 minutes for the placebo, 250- mug, and 500-mug groups (p = 0.27). Postoperative morphine requirements in the 250-mug and 500-mug groups were 13.6 +/- 7.8 mg and 11.7 +/- 7.4 mg, co mpared with 21.3 +/- 6.2 mg in the placebo group (p = 0.002). There were no differences among the study groups with regard to postoperative midazolam, nitroglycerin, and sodium nitroprusside requirements. Conclusions: Despite decreased postoperative morphine requirements, intrath ecal morphine administration did not have a clinically relevant effect on e xtubation time after CABG surgery. This study suggests that 250 mug is the optimal dose of intrathecal morphine to provide significant postoperative a nalgesia without delaying tracheal extubation. Copyright (C) 2000 by W.B. S aunders Company.