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

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 B_DexIT(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 B_DexIV(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 B_DexIT> Group B_DexIV> Group B (P < 0.001). Patients in Group B_DexITand Group B_DexIVwere sedated but easily arousable. Conclusion: Intrathecal dexmedetomidine prolongs the effect of subarachnoid anesthesia with arousable sedation when compared with intravenous dexmedetomidine.