Bioelectric impedance analysis of acute body water changes in congestive heart failure.

The body water changes indicated by bioelectric impedance analysis (BIA) and body weight were studied in 12 patients admitted to hospital for acute treatment of congestive heart failure (NYHA-class II-III). BIA was performed at the time of admittance and on the third day by using a multifrequency technique, which allows simultaneous estimation of the total body water (TBW) and the extracellular fluid (ECF) and intracellular fluid (ICF) volumes. The body weight at admittance was 85+/-20 kg. Body weight correlated with the body water compartments (r - 0.9, p<0.001). From day 1 to day 3, the body weight decreased by 2.9+/-1.7 kg. BIA estimated the corresponding reductions of the physiological body fluid spaces to 3.2+/-2.4 L (TBW), 2.7+/-1.6 L (ECF) and 0.5+/-3.2 L (ICF). These results indicate that diuretic treatment for acute congestive heart failure mainly lowers the ECF volume. However, changes in body weight correlated poorly with changes in TBW, r=-0.11. We conclude that, although BIA corresponded well to the weight changes at the group level, a poor correlation in individual patients suggests that BIA is not a suitable tool to monitor the fluid balance in patients with acute congestive heart failure undergoing diuretic treatment.