Objective To explore the feasibility of tissue fluid resistivity measurement for healthcare management, we evaluated the uniformity of the extracellular (ρe) and intracellular (ρi) fluid resistivity in a lower leg (by measuring at different electrode distances). Methods Ten health volunteers were involved in the test with a four-electrode bioimpedance spectroscopy. The measurement was performed with excitation frequencies from 1kHz to 100kHz. Two measuring electrodes were set on one lower leg at the distances of 5cm, 10cm and 15cm. Voltage amplitude, phase angle, ρe and ρi were analyzed. Results The measured impedance increased with the distance of the measuring electrodes, and the resistivity changed little with the distance. No obvious difference between extracellular and intracellular fluid resistivity was observed. In addition, voltage amplitude and phase angle were influenced by the frequencies of excitation signals. Conclusions The resistivity in a lower leg measured with the four-electrode bioimpedance spectroscopy is likely uniform. The resistivities of extracellular fluid and intracellular fluid are similar.
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