Intravenous Dexmedetomidine Has Synergistic Effect on Subarachnoid Block with Hyperbaric Bupivacaine

Objective To assess the effect of intravenous dexmedetomidine on subarachnoid anesthesia with the help of hyperbaric bupivacaine when administered as a bolus or as an infusion. Materials and methods This randomized control trial was conducted at the Department of Anesthesia, Nishtar Hospital, Multan, Pakistan, from January 2017 to December 2018. Seventy patients were enrolled in the study. Patients were segregated into three groups. At the T10 level, a sensory blockade was noted. The motor blockade was also periodically measured until a modified Bromage score of three was achieved. The depth of sedation was measured with the help of the Ramsay Sedation Scale score. Oxygen saturation and other factors were also measured and recorded. Nausea, vomiting, diarrhea, and pruritus were the adverse effects noted during the study. To check and compare the statistical differences among the variables from different groups, the Chi-square test and analysis of variance test were performed. A probability (p) value of <.05 was considered statistically significant. Results The duration of the sensory blockade was shortest in the control group receiving only bupivacaine (Group B) and longest in the group receiving bupivacaine plus dexmedetomidine as a single bolus (Group BDexB; p: <.001). The time of complete sensory and motor recovery was longest in Group BDexB and shortest in Group B. The difference was statistically significant (p: <.001). The Ramsay score was >2 (i.e., 3 or 4) in five patients from Group B, 19 from Group BDexB, and 17 from the group receiving intrathecal bupivacaine plus dexmedetomidine as an infusion (Group BDexI). Between these groups, a statistically significant difference was found (p: <.001). Conclusions Intravenous administration of dexmedetomidine as either a bolus or infusion prolonged the duration of the sensory and motor blockade.