| Changes in Power Spectrum of R-R Interval Variability According to the Changes in End Tidal Concentration of Inhalation Anesthetics. |
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Jong In Han, Choon Hi Lee |
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Department of Anesthesiology, College of Medicine, Ewha Womans University, Seoul, Korea. |
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| Abstract |
BACKGROUND
Heart rate variability provides us with many informations of autonomic activities of cardiovascular system. Among the many methods of analyzing R-R variability, power spectral analysis is understood to be the most useful, quantitative, and noninvasive method which represents the changes of frequency. And the power spectral density is composed of three components in power, a high frequency at 0.15~0.5Hz, a middle frequency at 0.10-0.15 Hz, and a low frequency at 0.04~0.08Hz.
METHODS
The each frequency power of the R-R interval variability was checked in the 8 mongorean dogs according to the changes in end tidal concentration of halothane, enflurane and isoflurane, and the relationship was measured.
RESULTS
The power of three frequency bands decreased at 1.0 and 1.5MAC and increased at 2.0MAC halothane compared with previous MAC respectively. The power increased at 1.0 and 1.5MAC and decreased at 2.0MAC enflurane compared with previous MAC respectively. There was no correlation between the power of three frequency bands and the changes of end tidal concentration of isoflurane. The low/high ratio associated with the changes of end tidal concentration of inhalation anesthetics increased at 1.0 and 1.5MAC and decreased at 2.0MAC compared with previous MAC respectively.
CONCLUSIONS
In our study we confirmed that spectral analysis of R-R interval variability might reflect the balance between sympathetic and parasympathetic activity and low/high ratio would be a convenient index of such interaction during anesthesia within the clinical range of end tidal concentration of inhalation anesthetics. |
| Key Words:
Anesthetics; volatile; halothane; enflurane; isoflurane; Sympathetic nervous system; R-R interval |
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