Intrathecal morphine and clonidine for coronary artery bypass grafting

Abstract

Background. After cardiac surgery adequate postoperative analgesia is necessary. We assessed analgesia using intrathecal morphine and clonidine. Methods. In a double-blind randomized study, 45 patients having coronary artery bypass graft surgery were allocated randomly to receive i.v. patient-controlled analgesia (PCA) morphine (bolus, 1 mg; lock-out interval, 7 min) (control group), either alone or combined with intrathecal morphine 4 μg kg-1 or with both intrathecal morphine 4 μg kg-1 and clonidine 1 μg kg-1. Intrathecal injections were performed before the induction of general anaesthesia. Pain was measured after surgery using a visual analogue scale (VAS). We recorded i.v. PCA morphine consumption during the 24 h after operation. Results. Morphine dosage [median (25th-75th percentiles)] was less in the first 24 h in the patients who were given intrathecal morphine + clonidine [7 (0-37) mg] than in other patients [40.5 (15-61.5) mg in the intrathecal morphine group and 37 (30.5-51) mg in the i.v. morphine group]. VAS scores were lower after intrathecal morphine + clonidine compared with the control group. Time to extubation was less after intrathecal morphine + clonidine compared with the i.v. morphine group [225 (195-330) vs 330 (300-360) min, P<0.05]. Conclusion. Intrathecal morphine and clonidine provide effective analgesia after coronary artery bypass graft surgery and allow earlier extubation.