BIOELECTRICAL-IMPEDANCE ANALYSIS - CLINICAL TOOL IN ASSESSING TOTAL-BODY WATER AND THORACIC FLUID

Bioelectrical impedance analysis forms a non-invasive tool for detecti on of body fluids. Total body measurement gives total body wafer (TBW) and, in case of multifrequency analysis, of intra- and extracellular fluid volume. The thoracic approach measures thoracic fluid (TF). The set-up of both techniques is discussed. An overview is given of the cl inical usefulness of the total body technique to monitor fluid changes and the process of refill during hemodialysis and to detect dry weigh t. The simultaneous measurement of TBW and TF was applied to obtain a more detailed picture of the body fluids. In a group of healty subject s the age dependency of both variables was shown. During hemodialyss T BW and TF showed a major and comparable decrease. Fluid retention duri ng cardiac surgery led to a slightly more pronounced increase of TF th an of TBW. The combination of both impedance techniques offers clinici ans a means to monitor alterations in fluid status in patients in more detail.