Abstract
There are three dispersions in the electrical properties of living tissues. They are α, β andγ dispersions. β dispersion is the relaxation phenomenon related to the structure of tissues between about 1 kHz and 1 MHz in frequency. In this frequency range, the electrical equivalent circuit of legs is represented with two resistances and a capacitance. One of these resistances is related to the intracellular fluid resistance and the other, to the extracellular fluid resistance. The capacitance shows the capacity of cell membrane. Therefore, from the frequency characteristics near the β dispersion, we can get much useful information related to the structure of tissues. For example, the information includes the ratio of intracellular fluid volume and extracellular fluid volume, the electrical properties of cell membrane, and etc. Under this equivalent circuit, we analyzed the electrical impedance of legs theoretically and experimentally.
From the results, it has been concluded that
(1) the electrical impedance of legs shows the β dispersion between 30 kHz and 50 kHz in frequency,
(2) the relaxation time constants are not represented by only one value but are distributed,
(3) the electrical equivalent circuit of legs is shown by two resistances and a capacitance,
(4) one of these resistances is related to the intracellular fluid volume and the other, to the extracellular fluid volume, and
(5) it is useful to apply this impedance method to clinical diagnoses, for example, to monitoring of dialysis, diagnosis of cardiac failure, pulmonary oedema, etc.
