Bispectral index-guided intraoperative sedation with dexmedetomidine and midazolam infusion in orthopaedic surgery of lower limbs

Abstract

Objective To compare and evaluate the effect and safety of dexmedetomidine(DEX) and midazolam sedation in lower limbs orthopaedic surgery. Methods Fifty-two patients undergoing lower limbs surgery were randomly assigned to group D (n=27,DEX, 0.5 μg·kg-1·h-1, loading dose 0.5 μg/kg) and group M(n=25, midazolam, 50 μg·kg-1·h-1, loading dose 30 μg/kg). An infusion was administered after mounting a bispectral index (BIS) monitor under combined spinal-epidural anesthesia. The target BIS level was≤85. An additional bolus dose of the study drug or cessation of the infusion was adjusted according to the BIS level, and the change should be recorded. Respiratory rates (RR), heart rate (HR), pulse oxygen saturation (SpO2), mean arterial blood pressure (MAP) were continually monitored. Sedation should be evaluated according to the Ramsay sedation scale(RSS) before the drug withdrawal. Results HR was lower in group D (72±7) bpm than that in group M (83±8) bpm (P<0.05) 30 min after infusion. There was no significant difference in the RR, MAP and RSS score between two groups. Dose adjustments were required in six and seven patients Groups D and M, respectively. Five patients needed to raise the mandible due to SpO2 decline by glossocoma in Group M, but none in Group D. Conclusion DEX infusion mildly decreased heart rate in the later periods of lower limbs surgery, with no significant influences on the MAP. Compared with midazolam, DEX might show more advantages in maintaining the unobstructed of the respiratory tract, and be more suitable for sedation in lower limbs surgery. Key words: Bispectral index; Dexmedetomidine; Midazolam; Lower limbs of orthopaedic surgery