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 hyperbaric bupivacaine.

Hundred adult patients scheduled for lower abdominal surgeries were randomized in two 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 7.5 μg dexmedetomidine (Group D) 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.

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. Hemodynamic stability was maintained in the two groups.

Intrathecal dexmedetomidine in doses of 7.5μg significantly prolong the anesthetic and analgesic effects of spinal hyperbaric bupivacaine.