Preemptive Epidural Morphine for Postoperative Pain Relief After Lumbar Laminectomy

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Abstract
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.