European Journal of Cardiovascular Medicine

Background: Alpha-2-adrenergic agonists have synergistic action on local anesthetics used in spinal anaesthesia. The objectives of this study was to compare the efficacy of intravenous dexmedetomidine with clonidine and placebo on sensory and motor blockade duration, and analgesia duration in patients undergoing lower limb surgeries under bupivacaine spinal anaesthesia. Methodology: A total of 90 ASA physical status 1 and 2 patients undergoing lower limb surgeries under spinal anaesthesia were randomized into three groups of 30 each in this prospective randomized controlled study. Group N (placebo group) received 10 ml of intravenous normal saline, group C (clonidine group) received 1μg/kg intravenous clonidine, whereas group D (dexmedetomidine group) received 0.5μg/kg of intravenous dexmedetomidine, all given 10min after administration of spinal anaesthesia with 15mg of 0.5% hyperbaric bupivacaine. Onset time and regression of sensory and motor blockade and duration of analgesia were recorded. Data was analyzed using analysis of variance or Chi-square test, with value of p<0.05 considered statistically significant. Result: Onset of sensory and motor blocks were similar across the groups, p>0.05. Duration of sensory and motor blocks were longer in dexmedetomidine group (295.7 + 37.3min and 307 + 29min), than clonidine group (187 + 13min and 229 + 31min) or placebo group (123 + 16.4min and 168 +20min), p<0.05. Duration to first postoperative rescue analgesia was longer in dexmedetomidine group (336.3 + 29.3min) as compared to clonidine (252.7 + 33.4min) and placebo(183.7 + 15.2min), p<0.05. Hypotension was significantly more in group D and group C as compared to group N, whereas other side effects were not significant and comparable among the groups.  Conclusion: Intravenous dexmedetomidine is superior to intravenous clonidine as an adjuvant to bupivacaine spinal anaesthesia for lower limb surgeries to prolong duration of sensory and motor blockade and duration of analgesia with similar side effects.