Preincisional dextromethorphan combined with thoracic epidural anesthesia and analgesia improves postoperative pain and bowel function in patients undergoing colonic surgery.

Colonic surgery is associated with severe postoperative pain and postoperative ileus, which contribute to delayed hospital discharge. In previous studies, we demonstrated that IM dextromethorphan (DM) provided preemptive analgesia and improved postoperative pain. The benefit of thoracic epidural anesthesia (TEA) and postoperative epidural analgesia on postoperative pain was well demonstrated. The goal of this study was to investigate the effect of preincisional IM DM combined with intraoperative TEA and postoperative patient-controlled epidural analgesia (PCEA) on pain and bowel function after colonic surgery. Patients were randomized into 3 equal groups to receive: 1) chlorpheniramine maleate (CPM) 20 mg and general anesthesia (CPM-GA); 2) CPM 20 mg and GA combined with TEA (CPM-TEA); or 3) DM 40 mg (containing 20 mg of CPM) and GA combined with TEA (DM-TEA). The CPM, DM, and TEA with lidocaine were administered after GA induction via an IM injection and 30 min before the skin incision. All patients received postoperative PCEA for pain control. Analgesic effects were evaluated for 72 h after surgery using visual analog scale pain scores at rest and moving, time to first PCEA request for pain relief, total PCEA consumption, and the time to first passage of flatus. Statistically significant improvement of postoperative pain and bowel function was observed in the following order: DM-TEA > CPM-TEA > CPM-GA. Compared with the CPM-TEA group, the DM-TEA group averaged 1.6 points lower on first-hour pain scores, 40 min longer to first PCEA request, 15.8 mL less PCEA drug over 72 h, and 14.7 h earlier bowel function (all P < 0.01). We conclude that the combination of preincisional DM (40 mg IM), intraoperative TEA, and postoperative PCEA enhances analgesia and facilitates recovery of bowel function, suggesting possible synergistic interaction with local anesthetics and opioids.