Midazolam more effectively suppresses sympathetic activations and reduces stress feelings during mental arithmetic task than propofol.
OBJECTIVE
The aim of the present study was to examine the effect of intravenous midazolam and propofol sedation on autonomic nervous activities during psychological stress, and whether these results are associated with changes in subjective stress feelings.


METHODS
Seven healthy male volunteers were included in a randomized crossover manner. The heart rate (HR), HR variability, arterial oxygen saturation, and bispectral index value were continuously monitored. A mental arithmetic task for 7 minutes was given with or without intravenous sedation with midazolam or propofol. A bispectral index value of 75 to 85 and an Observer's Assessment of Alertness/Sedation score of 4 were the targeted sedation level in both groups. HR variability was assessed using the power spectral analysis (low-frequency [LF] and high-frequency [HF] components and LF/HF ratio). The faces anxiety scale was used to grade their stress feelings after each mental arithmetic task.


RESULTS
During the mental arithmetic task with intravenous sedation, no differences were found in the bispectral index values, arterial oxygen saturation, or the results of the mental arithmetic task between the 2 groups. The HR, LF/HF ratio, and normalized unit LF increased, and the normalized unit HF decreased in both groups. However, the percentage of changes in LF/HF ratio, normalized unit LF, and normalized unit HF were smaller in the midazolam group. In addition, the reduction in faces anxiety scale was greater in the midazolam group.


CONCLUSIONS
These results suggest that midazolam more effectively suppresses sympathetic nervous activation and reduces subjective stress feelings during a mental arithmetic task than propofol.
Tsugayasu
Rie
R
Department of Dental Anesthesiology, Tokyo Dental College, Chiba, Japan. tsugarie@tdc.ac.jp
Handa
Toshiyuki
T
Kaneko
Yuzuru
Y
Ichinohe
Tatsuya
T
D000328:Adult; D001288:Attention / Q000187:drug effects; D056805:Consciousness Monitors; D018592:Cross-Over Studies; D016854:Dental Anxiety / Q000517:prevention & control; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D008874:Midazolam / Q000494:pharmacology* / Q000627:therapeutic use; D010100:Oxygen / Q000097:blood; D015742:Propofol / Q000494:pharmacology* / Q000627:therapeutic use; D013315:Stress, Psychological / Q000517:prevention & control*; D013564:Sympathetic Nervous System / Q000187:drug effects*
D006993:Hypnotics and Sedatives; D008874:Midazolam; D010100:Oxygen; D015742:Propofol