Abstract

Background: An increased dose of dexmedetomidine during sedation can lead to increased side effects such as bradycardia and hypotension. The purpose of this study was to investigate the incidence of bradycardia was different depending on whether BIS was monitored in sedation using dexmedetomidine.
Methods: Fifty patients between 20 and 60 years old who underwent spinal anesthesia were included in this study. The patients were divided into two groups (control and BIS groups). Both the control and BIS groups were administered a loading dose of 1 μg/kg dexmedetomidine for the first 10 min (without BIS monitoring in the control group), followed by a maintenance dose of 0.2 μg/kg/h in the control group. The maintenance dose in the BIS group was administered at the discretion of the anesthesiologist to maintain the BIS score between 50 and 70. The baseline heart rate (HR), lowest HR, and difference between baseline and lowest HR was calculated.
Results: The baseline HR in the control and BIS groups was 74.4±11.0 beats per minute (bpm) and 80.9±16.0 bpm, respectively (P=0.098). The difference between the baseline and lowest HR in the control and BIS groups was 19.4±7.6 bpm and 25.5±8.8 bpm, respectively (P=0.011). Low baseline HR was positively correlated with a reduced lowest HR.
Conclusions: The incidence of bradycardia during sedation with dexmedetomidine decreased with BIS monitoring. Patients with a low baseline HR were more likely to develop bradycardia during sedation with dexmedetomidine. Therefore, BIS monitoring may be helpful in patients with low baseline HR.

Key words: bispectral index monitor; Dexmedetomidine; heart rate; spinal anesthesia