Analgesic Efficacy of Intravenous Lidocaine Infusion in Cesarean Section under Spinal Anesthesia: A Prospective Randomized Double-Blind Study

Background & Objective: Nowadays, conventional analgesic agents that are usually used for pain killing after cesarean sections do not provide enough analgesia with infrequent serious side effects. Lidocaine has been suggested as an adjuvant analgesic agent for postoperative pain relief. We designed this randomized double-blind, placebo-controlled study to evaluate the analgesic efficacy of intravenous (IV) lidocaine in patients undergoing a cesarean section under spinal anesthesia. Materials & Methods: Eighty patients undergoing elective cesarean section under spinal anesthesia were randomly divided into two groups to receive intravenous ۱.۵ mg/kg of lidocaine ۲% bolus ۱۵ minutes prior to spinal anesthesia followed by an intravenous infusion of ۱.۵ mg/kg/h for ۶۰ minutes (L group) or ۰.۹% sodium chloride (C group) in a double-blind fashion. The time until the first request for an analgesic, the duration of sensory and motor blockade, hemodynamic variables and adverse events were recorded. Results: The difference in sensory (۹۵% CI ۱۰.۱۸ to ۱۸.۰۱; P≤۰.۰۰۱) and motor (۹۵% CI ۳۵.۵۰ to ۵۰.۱۹; P≤۰.۰۰۱) blockade durations between groups L and C were significant. Similarly, the mean time until the first analgesic request was longer in group L (۱۷۵.۳۷±۲۱.۴۳) than in group C (۱۵۷.۱۲±۱۵.۲۵); the difference between the two groups was significant (۹۵% CI۹.۹۵ to ۲۶.۵۴; P<۰.۰۰۱). Conclusion: Intravenous lidocaine given as a supplementary agent in patients undergoing cesarean section under spinal anesthesia prolonged the duration of the sensory and motor blockade of spinal anesthesia and delayed the first analgesic request by patients without hemodynamic disturbance, respiratory depression and compromising the fetus.