Intrathecal Dexmedetomidine Enhances Intrathecal Combination of Magnesium Sulphate and Bupivacaine Quality of Spinal Anesthesia and Postoperative Analgesia

Background: No drug, used as adjuvant to spinal bupivacaine has yet been identified that specifically inhibits nociception without its associated side effects. The goal of neuraxial drug combination is to provide better analgesia with reduction in the incidence and severity of side effects. Objective: This prospective randomized double-blind study was conducted to evaluate the analgesic and adverse effects of intrathecal dexmedetomidine when added to intrathecal magnesium sulphate in patients undergoing lower abdominal surgery under bupivacaine spinal anesthesia. Methods: Ninety adult patients classified as ASA I and II scheduled for lower abdominal surgery were randomized to one of three groups. Each patients was given 3.6ml spinal injectate that consisted of 3ml 0.5% hyperbaric bupivacaine and 0.6ml containing either, normal saline (group C), 50mg magnesium sulphate (group Mg), or 50mg magnesium sulphate and 5ug dexmedetomidine (group MgD). The onset time to reach peak sensory and motor level, the regression time for sensory and motor block, hemodynamic changes, pain score, time to rescue analgesic, level of sedation and adverse effects were recorded intraoperatively and up to 24 hours after spinal anesthesia. Results: The onset time to reach peak sensory and motor level was shorter in group MgD as compared with the control group C ( p<0.007), and it was significantly prolonged in group Mg (p<0.001). In both Mg group and MgD group when compared with group C, there was a significant prolonged time to two segment regression, sensory regression to S1, regression to Bromage 0 and time to first rescue analgesic in addition to a significant decreased postoperative pain scores and lower postoperative analgesic requirements. The effects were greater in group MgD than in group Mg. Hemodynamic stability was maintained and other side effects were irrelevant in the three groups.

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