ANALGESIC EFFECT OF INCISIONAL MORPHINE FOLLOWING INGUINAL HERNIOTOMYUNDER SPINAL-ANESTHESIA

Background and Objectives. Opioids have been shown to possess antinoci ceptive effects after peripheral administration in experimental and cl inical studies. The results of clinical studies on intra-articularly a dministered morphine are, however, conflicting. The objective of this study was to examine a possible analgesic effect of incisionally admin istered morphine on postoperative pain in patients undergoing inguinal herniotomy. Methods. Forty outpatients were included in a double-blin d, randomized, placebo-controlled study. The patients had spinal anest hesia with 1.5-2.0 mL hyperbaric 5% lidocaine. At conclusion of hernio tomy morphine 5 mg was injected incisionally in 10 patients, intraveno usly in 10, and subcutaneously in 10. The placebo group of 10 patients had saline injected in the incision. Postoperative pain was assessed with a visual analog scale at rest and during mobilization. Assessment s were made immediately before and at 0, 2, 4, and 6 hours after herni otomy and on the second and seventh postoperative days. At the same ti mes morphine and acetaminophen consumptions were recorded. Results. Th ere were no significant differences in postoperative visual analog sco res between the groups. Except for the cumulative morphine requirement from the second to the seventh postoperative day, which was significa ntly higher in the placebo group than in other groups, no significant differences in cumulative morphine and acetaminophen requirements were found between the groups. Conclusions. A single 5-mg dose of morphine injected in the herniotomy wound did not affect pain scores or supple mentary analgesic requirements, which argues against a role of periphe ral opioid receptors in mediating analgesia.