Postoperative effects of intrathecal morphine in coronary artery bypass surgery

To determine whether intrathecal morphine is effective in decreasing analgesic and antihypertensive drug requirements after coronary artery bypass (CAB) surgery, a prospective, randomized, double-blind study was designed. Approximately 30 minutes before induction of anesthesia with IV sufentanil and diazepam, and 2 hours before heparinization, one group of patients (n = 16) were given morphine 0.5 mg, while the control group (n = 14) were given placebo intrathecal injections through 22- or 25-gauge lumbar puncture needles. Intraoperatively, there were no differences in the numbers of patients requiring vasodilator drugs or volatile agent titration. During the postoperative period, the treated group required significantly less (P less than 0.05) IV morphine compared with the placebo group, during the first 24 hours (1.8 +/- 0.7 vs 5.4 +/- 1.5 mg) and 30 hours (2.4 +/- 0.8 vs 8.3 +/- 1.9 mg). The treated group also required significantly less (P less than 0.05) sodium nitroprusside in the first 24 hours (58.1 +/- 29.0 vs 89.1 +/- 18.4 mg). There were no differences in pain scores, and the only complications (itching, nausea and vomiting) were infrequent. It is concluded that an intrathecal dose of 0.5 mg of morphine is efficacious in reducing analgesic and antihypertensive drug requirements after CAB surgery. Whether these results are clinically important enough to warrant the theoretical risks of postheparinization lumbar hematoma is a topic for further investigation.