"Dose related prolongation of hyperbaric bupivacaine by dexmedetomidinein lower abdominal and limb surgeries requiring spinal anaesthesia " A randomized double blind controlled study.

Background and Aims: 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. Materials and Methods: Ninety patients scheduled for major surgeries under spinal anaesthesia were chosen for the study. All patients received drug volume of 3.5ml containing 3 ml of hyperbaric bupivacine (15 mg). The study groups received dexmedetomidine 5 μg (group B,n = 30) or 10 μg (group C,n =30) diluted to 0.5 ml with 0.9% saline, added to bupivacaine in the same syringe, the control group (group A, n= 30) received an identical volume of 0.9% saline added to bupivacaine. Heart rate, arterial blood pressure, sensory level, motor block, pain and level of sedation were assessed intraoperatively and upto 24 hrs after spinal anaesthesia. The incidence of adverse effects were recorded. Result: Dexmedetomidine significantly prolonged time to two segment regression, sensory regression, 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 C than in group B. In addition, group C patients had higher sedation scores and lower postoperative analgesic requirements than group B or A. Hemodynamic stability was maintained in all the groups. Conclusion: Intrathecal dexmedetomidine in dose of 5 μg and 10 μg significantly prolonged the anesthetic and analgesic effects of spinal hyperbaric bupivacaine in a dose dependent manner. A 10 μg dose may be benefit for prolonged surgical procedure.