title: Total body water measurement by a modification of the bioimpedance spectroscopy method.
abstract: We propose a method for calculating directly total body water (TBW) volumes (V (t)) from whole body resistance extrapolated at infinite frequency (R (infinity)) using a XITRON 4200 impedance meter. Mean TBW resistivities for men and women were determined from measurements of R (infinity) and fat-free mass (FFM(d)) measured by DXA in 58 healthy subjects assuming an average hydration coefficient of 73.2%. Mean differences between V (t) measured by our new method and those deduced from DXA data were +0.11 +/- 1.61 L for women and +0.13 +/- 2.16 L for men. For validation, this method was tested with the same resistivities against a 2nd group of 16 volunteers and the mean difference between V (t) from impedance and DXA was -0.80 +/- 1.43 L. Since the resistance at 50 kHz (R (50)) was found to be equal, in average, to 1.230 R (infinity) for men and 1.223 R (infinity) for women, this method can also be applied at 50 kHz with a similar accuracy by estimating R (infinity) from R (50). When our new method was applied to the monitoring of water loss during 28 dialysis runs performed on 13 patients, it predicted a mean water loss equal to 94% of ultrafiltered volume.
authors.affiliation: UMR 6600, Department of Biological Engineering, Technological University of Compiègne, BP 20529, 60205, Compiegne Cedex, France. michel.jaffrin@utc.fr
authors.forename: Michel Y
authors.initials: MY
authors.lastname: Jaffrin
authors.forename: Marianne
authors.initials: M
authors.lastname: Fenech
authors.forename: Marie Valèrie
authors.initials: MV
authors.lastname: Moreno
authors.forename: Roland
authors.initials: R
authors.lastname: Kieffer
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000293:Adolescent; D000328:Adult; D000368:Aged; D001834:Body Water; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D006435:Renal Dialysis / Q000379:methods; D013057:Spectrum Analysis / Q000379:methods*