A model-based approach for analysis of intracellular resistance variations due to body posture on bioimpedance measurements

• Published in: Journal of physics. Conference series Vol. 434; no. 1; pp. 12003 - 4
• Main Authors: Weyer, Sören, Ulbrich, Mark, Leonhardt, Steffen
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2013
• Subjects: Body fluids; Capacitance; Computational fluid dynamics; Computer simulation; Electrodes; Equivalence; Fluid flow; Grounds; Mathematical models; Physics
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/434/1/012003

Bioimpedance spectroscopy is a known option for measuring body fluid volume. However, it is prone to a variety of influence factors which prevent a wider use. One of these influencing factors is the body posture. It could be shown that the average intracellular resistance percentage changes when the subject changes position from lying to standing. Most authors explain this phenomenon by fluid shifts. Another possible reason is the stray capacitance between the body and the ground, because if a certain fraction of the injected current follows other paths than between the potential electrodes, the result will be wrong. This paper analyses the influence of different body postures on the measured intracellular resistance and the posture depending capacity. For this purpose, FEM simulations are used. Subsequently, an electrical equivalent model with capacitances was developed. With this model, it is possible to correct the measured impedance and to neglect the influence of the stray capacitance.