Electrical measurement of fluid distribution in legs and arms

Intra- and extra-cellular fluid distribution is very important to know the physiological and clinical state of living subjects. However, it is quite difficult to measure the distribution in vivo. Electrical impedance of living tissue is mainly affected by extra-cellular fluid at an applied frequency lower than the beta-dispersion frequency, and is affected by both extra- and intra-cellular fluid at higher applied frequencies than that. In this paper, we discuss the problems of measurement of intra- and extra-cellular fluid distribution in living tissues by means of electrical impedance. The intra- and extra-cellular fluid distribution is related to some physiological parameters, such as blood circulation, metabolism of tissues, and the electrolytic concentration of intra- and extra-cellular fluids. Therefore, the information about the distribution of fluids in tissues is quite useful for the diagnosis of various diseases, the monitoring of seriously ill patients, and in medical treatments such as artificial dialysis. We discuss the method of measurement and the results of experiments.