Abstract
Measurement of living tissue impedance - bioimpedometry - started to be used in medicine some 50 years ago, first exclusively for estimation of extracellular and intracellular compartment volumes. Its most simple single frequency (50 kHz) version works directly with the measured impedance vector.
Technically more sophisticated versions convert the measured impedance in values of volumes of different compartments of body fluids and calculate also principal markers of nutritional status (lean body mass, adipose tissue mass). The latest version specifically developed for application in dialysis patients includes body composition modelling and provides even absolute value of overhydration (excess fluid).
Still in experimental phase is the bioimpedance exploitation for more precise estimation of residual glomerular filtration. Not yet standardized is also segmental bioimpedance measurement which should enable separate assessment of hydration status of the trunk segment and ultrafiltration capacity of peritoneum in peritoneal dialysis patients.