A Comparative Prospective, Randomised, Double Blind Study of the Effect of IV Dexmeditomidine on Subarachnoid Block Versus 0.9 % Normal Saline as Control

The objective of the study was to evaluate the effect of intravenous dexmedetomidine on the duration of subarachnoid block, hemodynamic changes and sedation in patients undergoing surgeries under spinal anaesthesia with 0.5% of hyperbaric bupivacaine. It was a prospective randomised controlled double blind trial.100 ASA physical status I/II patients undergoing elective surgeries under spinal anaesthesia were randomized into two groups of 50 each. Immediately after subarachnoid block with 3 ml of 0.5% hyperbaric bupivacaine, group D patients received a loading dose of 1 μg/kg of dexmedetomidine intravenously by infusion pump over 10 mins followed by a maintenance dose of 0.5 μg/kg/hr till the end of surgery whereas group C received an equivalent quantity of normal saline by infusion pump. Time taken for regression to Modified Bromage Scale 0, level of sensory block, two dermatomal regression of sensory blockade, duration of sensory block, intraoperative Ramsay sedation scores and time to first request for postoperative analgesic were higher in group D compared to group C (p values < 0.001). The 24 hours mean analgesic requirement is less in group D than group C (p value < 0.001). In conclusion, intravenous dexmedetomidine significantly prolongs the duration of sensory and motor block of bupivacaine spinal anaesthesia with good hemodynamic stability.