Portable Body Impedance System for Long-Term Monitoring of Body Hydration

Abstract:
The use of Bioelectrical Impedance Analysis (BIA) for assessing body composition is widespread both in healthy subjects and patients. However, until now its use has been limited to laboratory environments or at the patients’ bedside. A portable system measuring body impedance in a wide range of frequencies (10 Hz-1 MHz) would allow to assess the body water content in a much larger number of applications, including for instance monitoring the hydration state in endurance athletes during sport performances or in elderly subjects during daily activities. Aim of this work is to demonstrate the feasibility of long-term (several hours) bioimpedance monitoring by means of a portable multifrequency device. This is done by analyzing the influence of different electrode set-up; by performing preliminary recordings to evaluate measures stability over long periods and after postural changes; and finally by developing a prototype of DSP-based portable system for BIA, that minimize the number of components and the power consumption. Keywords – Bioelectrical Impedance Analysis, body impedance, electrodes, DSP, analog interface