Effect of intrathecal dexmedetomidine versus intravenous dexmedetomidine on subarachnoid anesthesia with hyperbaric bupivacaine

Abstract

Background and Aim: Alpha-2 agonists such as dexmedetomidine when given intravenously or intrathecally as an adjuvant potentiate subarachnoid anesthesia. We studied the difference in subarachnoid anesthesia when supplemented with either intrathecal or intravenous dexmedetomidine. Material and Methods: Seventy-five patients posted for lower limb and infraumbilical procedures were enrolled for a prospective, randomized, double-blind, placebo-controlled study and divided into three groups: Group B (n = 25) received intravenous 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%bupivacaine + 0.2 mL sterile water; Group BDexIT(n = 25) received intravenous 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%b upivacaine + 0.2 mL (5 μg) dexmedetomidine; Group BDexIV(n = 25) received intravenous dexmedetomidine 1 μg/kg in 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%b upivacaine + 0.2 mL sterile water. Onset and recovery from motor and sensory blockade, and sedation score were recorded. Onset of sensory and motor blockade was assessed using Kruskal-Wallis test, whereas 2-segment regression and recovery was analyzed using ANOVA and post hoc Tukey's test to determine difference between the three groups. P value <0.05 was considered statistically significant. Results: Although onset of sensory and motor block was similar in the three groups, motor recovery (modified Bromage scale 1) and two-segment sensory regression was prolonged in Group BDexIT> Group BDexIV> Group B (P < 0.001). Patients in Group BDexITand Group BDexIVwere sedated but easily arousable. Conclusion: Intrathecal dexmedetomidine prolongs the effect of subarachnoid anesthesia with arousable sedation when compared with intravenous dexmedetomidine.