Portable Bioimpedance Device and Monitoring of Hydration in a Healthy Person Before and After Exercise

The bioimpedance sensor recently developed at Imec was calibrated on the equivalent RC model of human body and tested on the volunteer undergoing repeated mild dehydration and rehydration. Some sources of variability in hydration assessment are observed that were not spotted and reported before. The specific protocols developed in this study enabled minimization of errors in altered hydration state. The bioimpedance method is shown to measure the hydration variation in a single person, with no need for averaging over large population. The predictable body fluid loss and gain was supported by dehydration and rehydration diets designed for accurate control of ion and water intake. The accuracy of fluid shift measurement down to a standard deviation of 300 ml is demonstrated, which exceeds capabilities of known methods and devices, including 'gold standards' like isotope dilution for hydration assessment.