INTRATHECAL NEOSTIGMINE FOR POSTOPERATIVE ANALGESIA AFTER ORTHOPEDIC-SURGERY

Study Objective: To establish a dose-response curve for the analgesic effect of intrathecal neostigmine in patients undergoing below knee su rgery with spinal anesthesia. To assess adverse effects, principally n ausea and vomiting. Design: Randomized, double-blind prospective study . Setting: Teaching hospital. Patients: 60 ASA physical status I and I I premedicated patients undergoing orthopedic surgery (tibial or ankle reconstruction). Interventions: Spinal anesthesia was performed at th e sitting position, L-3-L-4 interspace, 4 ml final volume, injected at a rate of 1 ml/10 sec. The control group (CG) received 15 mg hyperbar ic bupivacaine 0.5% plus saline. The 25 mu g neostigmine group (25NG) received 15 mg hyperbaric bupivacaine plus 25 mu g neostigmine; the 50 mu g neostigmine group (50NG) received 15 mg hyperbaric bupivacaine p lus 50 mu g neostigmine; and the 100 mu g neostigmine group (100NG) re ceived 15 mg hyperbaric bupivacaine plus 100 mu g neostigmine. Patient s were placed supine after the spinal punction. Measurements and Main Results: Time to first rescue analgesics, analgesia, and adverse effec ts at constant intervals were assessed using the 10 cm visual analog s cale (VAS). Intrathecal neostigmine produced a dose-independent reduct ion in the postoperative rescue analgesic consumption (p < 0.0001). Th e time to first rescue analgesics was similar among groups (p > 0.05), and the overall 24-hour VAS pain scores were lowest for patients who had spinal neostigmine (p < 0.02). The 100NG group had the highest inc idence of postoperative nausea and vomiting of all the groups (p < 0.0 5). Conclusion: Intrathecal neostigmine produced a dose-independent an algesia and a dose-dependent incidence of adverse effects with the dos es studied. (C) 1997 by Elsevier Science Inc.