Noninvasive estimation of fluid shifts between body compartments by measurement of bioelectric characteristics

Abstract

Previous research has established that bioelectrical characteristics of the human body reflect fluid status to some extent. It has been previously assumed that changes in electrical resistance (R) and reactance (X) are associated with changes in total body water (TBW). The purpose of the present pilot investigation was to assess the correspondence between body R and X and changes in estimated TBW and plasma volume during a period of bedrest (simulated weightlessness). R and X were measured pre-, during, and post- a 13 day bedrest status. Although a clear relationship was not elucidated, evidence was found suggesting that R and X reflect plasma volume rather than TBW. Indirect evidence provided by previous studies which investigated other aspects of the electrical/fluid relationship, also suggests the independence of TBW and electrical properties. With further research, a bioelectrical technique for noninvasively tracking fluid changes consequent to space flight may be developed