A prospective randomized study of preemptive analgesia for postoperative pain in the patients undergoing posterior lumbar interbody fusion: continuous subcutaneous morphine, continuous epidural morphine, and diclofenac sodium.

STUDY DESIGN: A prospective randomized clinical trial in preemptive analgesia for postoperative pain was conducted.

OBJECTIVE: To compare the efficacy of three preemptive analgesics combined with local anesthesia: continuous subcutaneous morphine (SC), continuous epidural morphine (ED), and diclofenac sodium (DS).

SUMMARY OF BACKGROUND DATA: Systemic opioids are known to be effective methods of postoperative pain control. The use of epidural morphine for postoperative analgesia has been a standard treatment in spinal surgery. Only a few studies in the literature have investigated the efficacy of preemptive analgesia using morphine. This is the first prospective randomized clinical trial to assess both subcutaneous and epidural continuous administration of opioids for preemptive analgesia.

METHODS: For this study, 73 patients were assigned randomly to one of three treatment groups: SC, ED, or DS. All patients underwent posterior lumbar interbody fusion with instrumentation. Pain management was assessed using the visual analogue scale (VAS). Usage of supplemental analgesics, the time to first request of them, and side effects were also investigated.

RESULTS: Twenty-two patients were randomized to SC, 23 to ED, and 27 to DS. No baseline variable differences among the three groups were seen. The results showed no significant difference in analgesic effects among those three preemptive analgesics. Only immediately after surgery (at 0 hours), the VAS of the DS group was lowest among three groups. But the DS group took more supplemental analgesic drugs until 72 hours, and the time to first request of this group was shorter than that of the other two groups. High rates of minor side effects were seen in both the ED and DS groups. SC gave moderate analgesic effects as well as the other two groups with few adverse effects.

CONCLUSIONS: DS provided a favorable effect immediately after surgery, but the effective time was short and the patient needed more supplemental drugs after that. ED did not give the expected effect, with comparatively high rates of side effects. Continuous epidural anesthesia did not seem to be suitable for preemptive analgesia. Continuous subcutaneous morphine brought some analgesic effects with a low rate of complications. It can be an attractive method for postoperative analgesia with technical ease.