Efficacy of Dexmedetomidine in two Different Doses as an Adjuvant to Lignocaine in Patients Scheduled for Surgeries under Axillary Block.

Abstract

The effect of adding dexmedetomidine (α2-adrenoceptor agonist) to local anaesthetics in brachial plexus blocks has been evaluated, however there has been no consensus regarding the ideal dose of dexmedetomidine. Without ultrasound axillary block has been considered as the safest approach for brachial block. To evaluate the efficacy of two doses of dexmedetomidine (0.5 μg/kg and 1 μg/kg) as an adjuvant to lignocaine in patients undergoing forearm surgeries under axillary brachial plexus block. This prospective randomized controlled study was conducted on 104 adult patients, American Society of Anaesthesiologists (ASA) physical status 1 or 2. They were randomized and given following drug formulations, Group L (n=35) received 23 ml of 2% lignocaine with adrenaline + 7 ml of saline, Group LD0.5 (n=34) received 23 ml of 2% lignocaine with adrenaline + 0.5 μg/kg of dexmedetomidine diluted in saline to make a volume of 7 ml, Group LD1 (n=35) was given 23 ml of 2% lignocaine with adrenaline + 1 μg/kg of dexmedetomidine diluted in saline to make volume of 7 ml, the total volume of drug being 30 ml in each group and concentration of lignocaine 1.5%. The duration of postoperative analgesia and demand for rescue analgesia were the primary outcomes and block characteristics taken as secondary outcome. Sensory and motor block onset times were shorter in Group L than in group LD0.5, LD1 (p < 0.05). Sensory and motor blockade durations were longer in Group LD1, LD0.5 than Group L (p<0.01). Duration of analgesia was longer in Group LD1 than in group LD0.5 and least in Group L (p<0.05). Dexmedetomidine (0.5 μg/kg and 1 μg/kg) as an adjuvant in axillary brachial plexus increases the duration of postoperative analgesia and delays the requirement of first dose of analgesic in a dose dependent manner and 1 μg/kg seems to be the near ideal dose of dexmedetomidine as an adjuvant in axillary block.