An Analysis of HRV Spectrum for Observing ANS Variations Caused by Sympathectomy and Vagotomy / 체질인류학회지

Increased death rate resulted from cardiovascular disease called for the study on the autonomic nervous system and cardiovascular system. It is known that an HRV (heart rate variability) spectrum analysis based on ECG (electrocardiograph) signals could be used to define activity of sympathetic and parasympathetic nervous system noninvasively. However, it is important to prove whether suggested HRV analysis method could provide the useful information for observing autonomic nervous system quantitatively and objectively before clinical application. In this study, 14 rats were used and divided into two groups, sympathectomy group and vagotomy group, respectively. During the experiment, ECGs of rats were collected three times at each experimental condition. After the application of Berger's series algorithm to the ECG raw data, HRV spectrum was obtained via FFT (fast Fourier transform). Power contents for each frequency bands were calculated from HRV waveforms. Two peak values, HF (high frequency) and LF(low frequency), representing autonomic nervous system status were used to extract the parameter, HF/LF ratio. Results showed that HF/LF values were increased for the sympathectomy group and decreased for the vagotomy group. It implies that the variations in HF/LF components exhibits the information for the classification of ANS(autonomic nervous system) function quantitatively. HRV analysis algorithm developed from this study could be expanded for the observation of autonomic nervous system variations in human.

The Change in P300 Component of the Long Latency Auditory Evoked Potential with Diazepam Sedation / 대한마취과학회지

BACKGROUND: P300 component of the long latency auditory evoked potentials (LLAEPs) provides information on conscious and cortical funtion. The P300 wave occures only for stimuli that somehow capture the patients attention. Therefore LLAEPs implys a degree of cognitive processing. We studied sedation scale and P300 wave to determine if LLAEPs could be utilized as electrophysiologic predictors of sedation. METHODS: The P300 component of LLAEPs from vertex was recorded from 10 ASA physical status I and II patients undergoing elective surgery while they listened via headphones to a series of clicks which were interrupted unpredictably by a tone burst (2 KHz) before and after diazepam 0.04 mg/kg and 0.08 mg/kg IV. The patients were asked to concentrate on the clicks and to press a button whenever they detected a 2 KHz tone. And sedation scale also was measured. RESULTS: Amplitude of P300 was decreased and latency of P300 was increased in a dose-dependent manner with IV diazepam. Amplitude was greatest and latency was shortest in awake. And sedation scale also was increased according to increased IV diazepam adminstration. CONCLUSIONS: Both amplitude and latency may be highly related to the sedation scale with progressively increasing dose of diazepam. Therefore we conclude that P300 component of LLAEPs can be utilized as an electrophysiologic predictor of awareness and sedation.