Bioelectric impedance analysis is a new, convenient and portable method used to estimate total body water and to assess body composition in healthy people. We used the tetrapolar bioelectrical impedance analysis method in 58 cirrhotic patients to assess its clinical applicability. Whole-body resistance, reactance and impedance were measured and compared with those of 30 healthy volunteers matched for age and sex. The resistance and impedance values of ascitic cirrhotic patients (resistance = 461 2 80 Jz; impedance = 462 f 80 0) and nonascitic cirrhotic patients (resistance = 487 f 96 0; impedance = 489 f 97 0) were comparable with the resistance (488 f 44 Jz) and impedance (491 f 44 0) of controls. However, a significant (p < 0.05) reduction in whole body reactance was found in patients with ascites and in those without ascites (34 & 9 0 vs. 47 f 12 Jz) as compared with healthy subjects (56 * 7 0). In 10 ascitic patients total body water was determined both before and after paracentesis; the volume of intraperitoneal fluid removed (7.9 * 3.8 L) could not be fully accounted for but only detected as an average volume of 1.9 f 1.0 L independently of the initial volume of the ascites. Our data clearly demonstrate that tetrapolar bioelectric impedance analysis is not adequate for measuring variations of "compartmentalized" fluid in the abdomen. (HEPATOLOGY 1991;13:892-895.)
Tetrapolar measurements of resistance (R) and reactance (Xc) by means of bioelectric impedance analysis (BIA) represent a new, safe, quick, noninvasive, portable and relatively accurate method for estimating total body water ( T B W ) and predicting body composition in healthy people (1-5). This method is based on the electric conductivity of fat-free mass and the geometric relationships between impedance (Z) and conductor volume as described by Ohm's law. For a better understanding of the principles underlying this method, the biological implications of these parameters should be made clear. R is the pure opposition of the body to an applied alternating electric current and is inversely related to the body fluids and electrolyte contents. Xc is the