Abstract
Information about the distribution of fluid in tissues is supposed to be quite useful for diagnosing various diseases, for monitoring seriously ill patients, bnd for medical treatment such as hemodialysis (HD), because the distribution of intra- and extra-cellular fluid (ICF & ECF) is affected by circulation, tissue metabolism, electrolytic equilibrium of ICF & ECF and so on.
It is well known that the impedance characteristics of living tissues have three kinds of frequency dispersion, called α, β, γ dispersions, due to different mechanisms of relaxation. Especially, the β dispersion phenomenon known as a structural relaxation can be used for estimating ICF & ECF distribution. The equivalent circuit with multiple time constants is presented as a model of the electrical properties of tissues near β dispersion frequency. It can give the equivalent resistivity RE & RI for ECF & ICF respectively. The frequency characteristics for calculating RE & RI are measured within 5 seconds by a microcomputer.
This paper deals with the frequency characteristics of human legs and arms as measured before and after dialysis and exercise. The body fluid remarkably decreases with dialysis. It has been shown that the ECF volume greatly decreases, but the ICF volume slightly increases by regular dialysis. It is suggested that a part of ECF moves into the cells. With high sodium dialysis, the ECF volume decreases and ICF volume also slightly decreases. These results well agree with the other laboratory data. The impedance before and after exercise has also been measured. The data oftained from ordinary persons are quite different from those of well-trained athletes. It is concluded that this method can be applicable to various clinical purposes.
