Localised impedance monitoring device for the remote clinical assessment of home-based dialysis patients.

BioImpedance Spectroscopy (BIS) has been clinically used to determine the hydrational status of patients undergoing haemodialysis (HD). In the present project we are developing a calf-localised, integrated impedimetric device to periodically and conveniently measure and transmit information on the hydrational status of home-based patients to a remote clinic. Surprisingly, we have found that simple postural changes before or during measurement lead to significant fluid shifts in the lower leg that are as important and as long lasting as the effects of haemodialysis. These must be taken into account if potentially hazardous errors are not to be made in assessing a patient's hydrational status.

Evaluation of a new impedancemeter to independently measure extracellular, intracellular and total body water volumes: application to the measurement of hydration.

The objective of this study was to evaluate the accuracy of independent hydric data for the quantification of total body water (V t), extracellular water (V e) and intracellular water (V i), obtained by a multifrequency impedancemeter Z-Métrix(®) (ZM), in standing and lying position, with respect to the Xitron reference. In a second step, the aim was to consider whether it is possible to quantify daily hydration. The average repeatability error of the ZM impedancemeter is less than 0.5 %. For total body water (V t), we note a low R (2) dispersion with an average of 0.9 for men and 0.6 for women. The estimation of extracellular water is equivalent to a maximum error of 3.1 % in standing position for women against 2.97 % for men in the same position. The estimation of the total body water by direct measurement and by summing the volumes of extracellular and intracellular water obtained by the Z-Metrix(®) shows very low dispersions with R (2) = 0.89 and average error from 1.3 % for healthy women in lying position to 3.9 % for healthy women in standing position. Finally, despite the impact of events on the daily measurements, it is viable to track a subject's overall hydration.