Abstract :
Background and Objectives: This study aims to investigate the effect of intrathecal administration of dexmedetomidine on the duration of sensory and motor block and postoperative analgesic requirements produced by spinal bupivacaine. Methods: Forty eight adult patients scheduled for anterior cruciate ligament reconstruction were randomized to one of three groups. Each patient was given 3.5 ml spinal injectate that consisted of 3 ml 0.5% hyperbaric bupivacaine and 0.5 ml containing either 10 μg dexmedetomidine (Group D1), 15 μg dexmedetomidine (D2) or normal saline (Group B). Heart rate, arterial blood pressure, sensory level, motor block, pain and level of sedation were assessed intraoperatively and up to 24 hours after spinal anesthesia. The incidence of adverse effects was recorded. Results: Dexmedetomidine significantly prolonged time to two segment regression, sensory regression to S1, regression of motor block to modified Bromage 0 and time to first rescue analgesic. In addition, it significantly decreased postoperative pain scores. The effects were greater in group D2 than in group D1. In addition, group D2 patients had higher sedation scores and lower postoperative analgesic requirements than Group D1 or B. Hemodynamic stability was maintained in the three groups. Conclusion: Intrathecal dexmedetomidine in doses of 10 μg and 15 μg significantly prolong the anesthetic and analgesic effects of spinal hyperbaric bupivacaine in a dose-dependent manner. A fifteen μg dose may be of benefit for prolonged complex lower limb surgical procedures.
