MULTIFREQUENCY IMPEDANCE IN THE ASSESSMENT OF BODY-WATER LOSSES DURING DIALYSIS

Multifrequency bioelectrical impedance was used to predict changes in body water compartments during renal dialysis. Weight loss during dial ysis was assumed to be water loss. Predicted total body water (TBW) fr om impedance after dialysis did not differ significantly from TBW dete rmined by deuterium oxide dilution. However, the predicted change in T BW from bioelectrical impedance largely exceeded the observed weight ( water) loss. The predicted change in extracellular water was slightly but significantly lower compared to the observed weight loss. The rati o of impedance at 1-100 kHz increased in all subjects during dialysis, and may be a simple tool to assess body water distribution.