Comparison of the Effect of Electrical Stimulations on the Chin Skin on Autonomic Nervous Activities During Propofol Sedation With or Without Midazolam.

PURPOSE: The aim of this study was to compare the effect of electrical stimulations on the chin skin on autonomic nervous activities evaluated by use of power spectrum analysis of heart rate (HR) variability during intravenous sedation using propofol with or without midazolam.

MATERIALS AND

METHODS

Thirty-eight healthy adult male volunteers underwent intravenous sedation with midazolam and propofol (group MP) and with propofol alone (group P) in a randomized crossover manner. In group MP, the participants received midazolam (0.04 mg/kg) and a target-controlled infusion of propofol with a predicted blood concentration of 1.0 μg/mL. In group P, the predicted blood concentration of propofol was maintained at 1.5 μg/mL. The observed variables were bispectral index value, systolic blood pressure, HR, high-frequency component (HF), low-frequency component (LF), and LF/HF ratio. Measurements were conducted over 100-second periods and carried out before, during, and after emergence from sedation by administering 0.2 mg of flumazenil. The paired t test, Wilcoxon t test, repeated-measures analysis of variance, and Friedman χ(2) r test were used for statistical analyses.

RESULTS

The mean age and body weight of the participants were 24.6 ± 2.8 years and 67.0 ± 7.9 kg, respectively. Bispectral index values, systolic blood pressure, and HR showed similar changes in both groups. The LF/HF ratio in group MP during sedation was lower than that before sedation; it also was lower than that in group P during sedation.

CONCLUSIONS

Intravenous sedation with a combination of midazolam and propofol inhibited sympathetic nervous activation induced by electrical stimulations to a greater extent than that with propofol alone.