Role of bioelectrical impedance analysis in follow-up of hospitalized elderly patients with congestive heart failure

Congestive heart failure (CHF) is characterized by high levels of B-type natriuretic peptide (BNP), expanded total body water (TBW) and extracellular water (ECW). Bioelectrical impedance analysis (BIA) has demonstrated high diagnostic accuracy in CHF but no information is available for older patients. We hypothesized that, in the follow-up of patients with CHF, body fluid changes estimated by BIA are related to BNP variations rather than with body weight. The aim of this study was to evaluate the relationship between variations in body fluid compartments, body weight and BNP in hospitalized elderly patients with decompensated CHF. 49 elderly patients admitted to the Geriatric Department for decompensated CHF were included in the study. On admission and at discharge, all patients underwent clinical and functional assessment and BNP dosage. TBW and ECW were also determined by the BIA method. At discharge, all patients showed reductions in TBW (DeltaTBW -2.9 3.0 liters), ECW (DeltaECW 1.9 2.1 liters) and BNP levels (DeltaBNP -219.6 458.1 pg/mL). Variations in TBW and ECW were correlated with BNP changes (r=0.65 and 0.62, respectively) rather than with body weight variations and BNP changes (r=0.51). The stronger relationship between fluid variations determined by BIA and BNP changes may make BIA a useful method in the follow-up of decompensated CHF elderly patients