Resistivity of Body Tissues at Low Frequencies

Abstract

The resistivity of tissues of the thorax of dogs has been measured in situ under nearly normal conditions. Additional data have been obtained from humans. Approximate values of tissue resistivity found are 160 ohm-cm for blood, 2,000 ohm-cm for lung, 2,500 ohm-cm for fat, 700 ohm-cm for liver, 250 and 550 ohm-cm (anisotropic) for heart muscle and 150 and 2,500 ohm-cm (anisotropic) for skeletal muscle. Reasons for the differences between these and previously reported values have been found, and in some cases, verified experimentally. Predictions of whole trunk resistivity based on anatomical data and these measurements are within 8% of actual trunk measurements.

Effect of tissue anisotropy on extracellular potential fields in canine myocardium in situ.

“…The anatomical anisotropy produces an electrical anisotropy (Rush, 1963;Clerc, 1976). Since myocardial cells are depolarized by local circuit currents which are affected by the tissue resistivity (Fozzard, 1979), the velocity of depolarization is anisotropic (Clerc, 1976;Roberts et al, 1979).…”

“…In view of the anisotropy of gross tissue resistivity (Rush, 1963) and of conduction velocity, it is not surprising that the extracellular voltage drop across a propagating depolarization wave depends on the direction of propagation. We have found that the extracellular voltage across a longitudinal wave is 1.75 ± 0.12 times as great as the voltage across a transverse wave.…”

“…It is unclear how this model should be extended to accommodate the known (Rush, 1963) electrical anisotropy of myocardium. Such an extension was required to compare with the results of our model.…”

Model of electrical conductivity of skeletal muscle based on tissue structure

“…6 the effect of changing the interelectrode distance from 0.05 cm, used in our experiments (GIELEN et al, 1984), to a value of the same order of magnitude as the interelectrode distance mentioned by RUSH et al (1963) (> 0'5cm) is illustrated. The values are calculated for a situation comparable with the four-electrode method, but with infinite large current electrodes.…”

Development of Bioelectric Impedance Measurement System Using Multi-Frequency Applying Method

“…When HF current was applied to human tissue, BI decreased because HF current flew in the inner cell. In other words, ECF was determined from BI measured by applying LF current, total body water (TBW) was measured by applying HF current, and ICF was estimated by subtracting the HF impedance value from the LF impedance value [18,19].…”