Preemptive epidural morphine for postoperative pain relief after lumbar laminectomy

This study was designed to evaluate the efficacy of preemptive epidural morphine for postoperative analgesia after lumbar laminectomy. Thirty ASA physical status I adults undergoing elective lumbar laminectomy under general anesthesia were randomly allocated to one of two groups. Group 1 (study group) received 3 mg epidural morphine preemptively 60 min before surgery, followed by epidural placebo at the end of surgery. Group 2 (control group) received epidural placebo at the same time preoperatively as the study group, followed by 3 mg epidural morphine at the conclusion of surgery. Pain was assessed using visual analog scales (VAS), and sedation was graded on a 4-point rank drowsiness score. Time to first postoperative analgesic (TFA), the supplementary analgesia, and the amount of morphine used over the 24-h period were noted for the groups. VAS pain scores were significantly less in Group 1 (preemptive group) than in Group 2 8 h after surgery (P < 0.05). TFA in the study group (19.9 +/- 2.3 h) was significantly prolonged compared with the control group (8.5 +/- 1.0 h, P < 0.05). The demand for supplementary analgesia and postoperative morphine consumption in the preemptive group was significantly lower than that in control group (P < 0.05). Patients in the control group were significantly sedated after 12 h and had a high incidence of nausea and vomiting (P < 0.05). The study shows that preemptive epidural morphine is superior to epidural morphine given postoperatively for pain relief after lumbar laminectomy.