Quantitative Analysis of Gastric Electric Stress Response with Chaos Theory

抄録

Electro-gastrograms, which are records of electrical activities of the stomach detected from the body surface, are approximately periodic waves. Therefore, characteristics of electro-gastrograms cannot be represented appropriately by frequency analysis. In this paper we evaluated the chaotic nature of electro-gastrograms during rest and under stress, in an attempt to quantify electro-gastrographic traces using the chaos theory. Gastric electric response of 26 healthy adults under stress of mental arithmetic for seven minutes were analyzed using the chaos theory and FFT method. Analytical results are as follows. All values of the Lyapnov exponent determined from electro-gastrograms were positive, suggesting that Electro-gastrograms have a chaotic nature. The Lyapnov exponent was significantly reduced during mental arithmetic compared with rest. However, there was no difference in the dominant frequency obtained by FFT between the period of rest and period of stress From the analytical results, it was suggested that Electro-gastrograms have characteristics of chaos. Moreover, the Lyapnov exponent, which is an index of a chaotic nature, more sensitively quantified the effects of stress than conventional frequency analysis in the analysis of electro-gastrograms.