Comparison between bioelectrical impedance spectroscopy measurements and water volume displacement of ankle oedema variations during the course of a day.

Objective: The purpose of this study was to find relationships between variations in bioelectrical impedance spectroscopy (BIS) measurements and those obtained by water displacement (WD) and calf (C) and ankle (A) perimetry on legs of patients with venous insufficiency and lower limb oedema, some with positive pitting test (PPT), others with negative pitting test (NPT).

Approach: Twenty-nine (29) female subjects were clinically examined prior to inclusion in the trial. Measurements were taken once in the morning and then 6 h later, using perimetry, WD, and then BIS; subjects were standing. Leg volume was assessed using two WD volumeters, one 'Tall' (TWD) and one 'Short' (SWD). BIS was performed using a SFB7 impedance meter device (Impedimed).

Main Results: Forty-three (43) legs with oedema were included. The results showed that 61% of the TWD variations variance was explained by SWD variations; less than 30% of the TWD variations variance was explained using BIS or perimetry alone, and 45% at best when used in combination. R, related to extracellular water, was the key BIS parameter. For NPT subpopulation (32 legs), the composite parameter (C - A)/R explained more than 60% of the TWD variations variance. For PPT subpopulation (11 legs), small or statistically non-significant variance explanations were found.

Significance: Combination of anthropometric and BIS parameters gave a better forecast of WD results than using only one or other. A novel composite parameter, (C - A)/R, better predicted TWD changes than other parameters hitherto used in literature, with improved estimates for the NPT subpopulation. Study n°ANSM 2017-A01063-50.