Simple estimation of excess fluid volume in hemodialysis patients based on multifrequency bioelectrical impedance analysis data

To develop a novel index of body water distribution status in hemodialysis (HD) patients, we derived equations that estimate the excess fluid volume (ExFv) in HD patients, and evaluated their applicability. The ExFv estimation equations were derived based on the correlations between extracellular water (ECW) and total body water (TBW) volumes of healthy adults, which were measured using multifrequency bioelectrical impedance analysis. Here, the effect of increasing ECW/TBW with age was corrected. The estimated ExFv and the circulatory and body fluid status of HD patients were compared between two groups of 20 patients with dry weight (DW) and 16 patients with overhydration (OH), both of which were clinically classified. The indices of circulatory and body fluid status were significantly higher in the OH group than in the DW group. The ExFv values of the DW and OH groups were 0.06 ± 0.19 L and 0.78 ± 0.32 L in males and 0.06 ± 0.16 L and 0.51 ± 0.18 L in females, respectively, indicating significantly higher values in the OH group. The derived ExFv estimation equations allow us a simple and quantitative assessment of the body water distribution status in HD patients.