Lauretti_1997_J.Clin.Anesth_9_473

STUDY OBJECTIVE To establish a dose-response curve for the analgesic effect of intrathecal neostigmine in patients undergoing below knee surgery with spinal anesthesia. To assess adverse effects, principally nausea and vomiting. DESIGN: Randomized, double-blind, prospective study. SETTING: Teaching hospital. PATIENTS: 60 ASA physical status I and II premedicated patients undergoing orthopedic surgery (tibial or ankle reconstruction). INTERVENTION: Spinal anesthesia was performed at the sitting position, L3-L4 interspace, 4 ml final volume, injected at a rate of 1 ml/10 sec. The control group (CG) received 15 mg hyperbaric bupivacaine 0.5% plus saline. The 25 micrograms neostigmine group (25NG) received 15 mg hyperbaric bupivacaine plus 25 micrograms neostigmine; the 50 micrograms neostigmine group (50NG) received 15 mg hyperbaric bupivacaine plus 50 micrograms neostigmine; and the 100 micrograms neostigmine group (100NG) received 15 mg hyperbaric bupivacaine plus 100 micrograms neostigmine. Patients were placed supine after the spinal punction. MEASUREMENTS AND MAIN RESULTS: Time to first rescue analgesics, analgesia, and adverse effects at constant intervals were assessed using the 10 cm visual analog scale (VAS). Intrathecal neostigmine produced a dose-independent reduction in the postoperative rescue analgesic consumption (p < 0.0001). The 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 incidence of postoperative nausea and vomiting of all the groups (p < 0.05). CONCLUSION: Intrathecal neostigmine produced a dose-independent analgesia and a dose-dependent incidence of adverse effects with the doses studied.