Application of bioimpedance technique in dialysis patients

Abstract

Bioimpedance data are mostly used to quantify the size (body composition, fluid volumes) and sometimes the anatomical location of tissue masses. Such measurements are usually confined to cases where pool sizes are static or slowly changing. These measurements are useful in monitoring patient progress in a variety of evolving clinical situations. Dynamic quantification of rapidly changing whole-body pool sizes is more demanding but is also needed. It has been achieved, especially during and surrounding dialysis therapy. Such measurements promise improved answers to the difficult question of how much water to remove during dialysis sessions. Anatomically specific dynamic quantification is a further step that appears capable of identifying sub-pools whose changes in size may predict and explain different predispositions to hypotension during the course of dialysis. The correlation of anatomically specific measurements of many kinds with bioimpedance is being used to validate information on pool dynamics when the pools cannot be precisely imaged and tracked. We present here bioimpedance data taken simultaneously on the leg, arm, and trunk of a group of 30 dialysis patients, 8 of whom were predisposed to hypotension, and 5 of whom had unusually high rates of water removal. These data can identify encumbered movement of water from the interstitial components of skeletal muscle to those of the trunk and are useful in predicting anatomical or situational predispositions to hypotension.