Clinical evaluation of combination of dexmedetomidine and midazolam vs. dexmedetomidine alone for sedation during spinal anesthesia

BACKGROUND: Dexmedetomidine is a useful sedative agent for spinal anesthesia. However, it has been reported to decreases heart rate in a dose-dependent manner. In the present study, we compared the bolus dose of midazolam and bolus loaded dexmedetomidine over 10 min to determine additional sedation methods. METHODS: A total of 100 patients who were classified as American Society of Anesthesiologists physical status I–II undergoing spinal anesthesia were randomly divided into two groups. In the combination of midazolam and dexmedetomidine group (group MD), 10 min after bolus loading of 0.05 mg/kg midazolam, 0.5 μg/kg/h dexmedetomidine was infused. In the dexmedetomidine group (group D), 1 μg/kg bolus dose of dexmedetomidine was infused over 10 min, and then 0.5 μg/kg/h dexmedetomidine was infused continuously. RESULTS: At 10 min, the sedation depth of the two groups was approximately the same. In both groups, the bispectral index (BIS) was within the optimal range of 55–80 and the Ramsay Sedation Scale score was within the optimal range of 3–5. Both patient and surgeon satisfaction with sedation did not differ between groups. At 10 min, heart rate (beats/min) was significantly lower (P < .01) in group D and mean blood pressure (mm Hg) was significantly lower (P < .01) in group MD. The prevalence of bradycardia (P = .714), hypotension (P = .089), and hypoxia (P = .495) did not differ statistically between the two groups. CONCLUSIONS: Midazolam bolus and dexmedetomidine continuous infusion may be a useful additional sedation method for patients who have severe bradycardia.