Differential effects of propofol and sevoflurane on heart rate variability.
BACKGROUND
Propofol is reported to reduce both sympathetic and parasympathetic tone; however, it is not clear whether the changes in heart rate variability are associated with depth of anesthesia. The purposes of the present study were (1) to evaluate the changes in heart rate variability at different depths of hypnosis and (2) to compare the effects of propofol on heart rate variability with that of sevoflurane.


METHODS
Thirty patients were randomly allocated into the propofol or sevoflurane for induction of anesthesia. The depth of hypnosis was monitored by the Bispectral Index (BIS). Spectral analysis of heart rate variability using a maximum-entropy method resulted in a characteristic power spectrum with two main regions, a high frequency (HF) and a low frequency (LF). Hemodynamics, entropy, LF, HF, and LF/HF were monitored when the patients were awake and after induction of anesthesia.


RESULTS
Both propofol and sevoflurane decreased blood pressure in a BIS-dependent manner, whereas heart rate showed no significant changes during the study period. In the propofol group, entropy and HF decreased with a reduction in the BIS value. Although LF decreased after induction of anesthesia, propofol caused no further decrease in LF in spite of a reduction in the BIS value. In the sevoflurane group, LF decreased with a reduction in the BIS value. Entropy and HF decreased after induction of anesthesia (BIS at 80); however, no further decreases were observed in spite of a reduction in the BIS value.


CONCLUSIONS
Induction of anesthesia with propofol decreased blood pressure, entropy, and HF in a BIS-dependent manner, indicating that propofol reduces cardiac parasympathetic tone depending on the depth of hypnosis. Conversely, sevoflurane did not show the BIS-dependent decreases in heart rate, blood pressure, HF, and entropy, indicating that sevoflurane has little or no effect on cardiac parasympathetic tone.
Kanaya
Noriaki
N
Department of fAnesthesioloty, Sapporto medical University School of Medicine, Sapporo, Japan. kanaya@sapmed.ac.jp
Hirata
Naoyuki
N
Kurosawa
Saori
S
Nakayama
Masayasu
M
Namiki
Akiyoshi
A
D000328:Adult; D000465:Algorithms; D018685:Anesthetics, Inhalation / Q000009:adverse effects*; D018686:Anesthetics, Intravenous / Q000009:adverse effects*; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects; D004809:Ephedrine / Q000494:pharmacology; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008738:Methyl Ethers / Q000009:adverse effects*; D008875:Middle Aged; D015742:Propofol / Q000009:adverse effects*; D000077149:Sevoflurane; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D008738:Methyl Ethers; D014662:Vasoconstrictor Agents; D000077149:Sevoflurane; D004809:Ephedrine; D015742:Propofol