Measurements of total body water with a foot-to-foot impedancemeter.

The objective was to set-up a method for measuring total body water volumes (TBW) using a Tefal foot-to-foot impedancemeter (FFI) by comparison with a multifrequency medical impedancemeter and to validate this method against deuterium dilution data. The investigation was carried out in 57 Caucasian adult subjects. Impedancemeters were a Tefal Bodymaster Vision (foot-to-foot) featuring a square wave signal and a Xitron Hydra 4200 (5-1000 kHz) using BIS method. TBW was measured by the Xitron using a new method that we have developed which applies the BIS method directly to extra and intracellular fluids combined. Although the high frequency impedance of the FFI (R(hf)) was higher than the Xitron infinite frequency resistance and corresponded to a frequency around 100 kHz, TBW differences between the FFI and Xitron were not significant, 0.17+/-2.17 L for men (P=0.694) and 0.04+/-1.88 L for women (P=0.902). Then, our method was tested on another Caucasian population in which R(hf) had been measured with the same FFI, together with TBW measurements by deuterium dilution. TBW differences between the FFI and dilution were -0.38+/-2.27 L for men (P=0.237) and -0.72+/-2.37 L for women (P=0.06). Our method permits, at least in a Caucasian healthy population, to measure TBW using this FFI with the same accuracy as a whole body multifrequency medical impedancemeter, and the measurement, made in upright position, is much quicker.