Effect of intravenous dexmedetomidine on bupivacaine spinal analgesia

Abstract

Background: Dexmedetomidine, a new α2 agonist, has been proven to prolong spinal anesthesia when administered through intrathecal route. This study was conducted to evaluate the effects of intravenous (IV) dexmedetomidine on spinal bupivacaine anesthesia. Materials and Methods: A prospective, randomized, double-blind, and placebo-controlled study was conducted on 80 female patients with the American Society of Anesthesiologists (ASA) grades I and II, aged 18-65 years undergoing abdominal hysterectomy under spinal anesthesia. After spinal anesthesia, patients in group D received a loading dose of 1 μg/kg IV dexmedetomidine over 10 min and followed by a dose of 0.2 μg/kg/h till the end of operative procedure, while patients in group C received the same calculated volume of normal saline. The time to reach peak sensory block level, time taken for two segment regression and maximum motor block, Ramsay sedation score, modified Bromage score, and visual analogue scale were recorded and were statistically analyzed using Statistical Package for Social Sciences (SPSS Inc. Chicago, IL, USA) Windows-based version 16.0. Results: Sensory regression to S1 was prolonged in the dexmedetomidine group compared to the control group (294 ± 18.2 min vs. 288 ± 24.3 min, P < 0.05). The time taken for motor block regression to modified Bromage score 6 in groups D and C were 263.73± 38.4 min and 251.7529.6 min, respectively (P = 0.008). Conclusion: IV infusion of dexmedetomidine significantly prolonged the duration of sensory and motor block of hyperbaric spinal bupivacaine with significant side effects.