Bioelectrical impedance in the clinical evaluation of liver disease

Liver disease is often characterized by an accumulation of excess body water as ascites, edema, or both. It was our purpose, using bioelectrical impedance analysis (BIA), to measure total body water (TBW) and extracellular water (ECW) in 35 patients with end-stage liver disease, including those undergoing orthotopic liver transplantation and, in 15 of these patients, to compare these values with measurements of TBW by deuterium oxide and of ECW by bromide dilutions. Poor correlation of TBW derived from BIA with TBW by deuterium dilution was found (r = 0.36, P = 0.35). In 19 patients, in whom TBW and ECW were not measured by dilution studies, 158 BIA measurements were taken for determining TBW. In 15 orthotopic liver transplantation patients with various amounts of fluid overload, a modest correlation was found between short-term weight change and BIA (r = 0.38, p = 0.001). In patients with fluid overload not exceeding 25% of ECW, ECW correlated with reactance (r = -0.96, P = 0.0025). TBW and ECW were covariant (r = 0.68, P = 0.01). In three patients with cirrhotic ascites, impedance measurements were taken with source electrodes on the hand and foot and detector electrodes on the abdomen during paracentesis of 8-11 L. Calculated volume of ascites correlated with measured volume (r = 0.99, P = 0.001). Segmental electrode placement and parallel impedance measurements were effective in determining ascites fluid volume.