Effect of intrathecal morphine before and after laminectomy on intra-operative surgical stress response and post-operative pain: A prospective randomized study.

Study Objective: Intrathecal administration of morphine.

Design: A prospective, randomized, controlled study.

Setting: Operating room.

Patients: Ninety patients of American Society of Anesthesiologists physical statuses I and II undergoing lumbar laminectomy.

Interventions: Pre-emptive versus post-operative intrathecal morphine injection, compared to a control group.

Main Outcome: The visual analog score at the time of discharge and 2, 4, 6, 8, 10, 12, 18, and 24 h later, serum cortisol level, the number of patients needing post-operative rescue analgesia, its duration, and the total amount required.

Main Results: Morphine sulfate consumption as rescue analgesia over 24-h post-operatively was significantly higher in general anesthesia group (Group I) than in pre-emptive intrathecal morphine groups (Group II) [p = 0.001] and then post-operative intrathecal morphine group (Group III) [p = 0.001], and it was higher in Group III than Group II [p = 0.001]. There was a greater need for post-operative rescue morphine in general anesthesia group (Group I) than in the other two groups, and it was greater in post-operative intrathecal morphine group (Group III) than in pre-emptive in-trathecal morphine group (Group II). At 30 min after surgical incisions and at 1 and 24 h after surgery, serum cortisol levels were significantly higher in general anesthesia group (Group I) [p = 0.001] and in post-operative intrathecal mor-phine group (Group III) [p = 0.001] than in pre-emptive intrathecal morphine groups (Group II), with no significant differ-ence between general anesthesia group (Group I) and post-operative intrathecal morphine group (Group III) [p = 0.704, 0.263, and 0.943, respectively].

Conclusion: Pre-emptive intrathecal morphine analgesia is an effective technique for controlling surgical stress re-sponse and post-lumbar laminectomy pain.