Body fluid status assessment by bio-impedance analysis in patients presenting to the emergency department with dyspnea

Background/Aims: Fluid retention occurs in patients with heart failure, accounting for dyspnea. We investigated the diagnostic implication of body fluid status, assessed by bio-impedance analysis (BIA), in acute heart failure (AHF) among patients who presented with dyspnea. Methods: A total of 100 patients who presented with dyspnea and suspected with AHF were analyzed in this study. We enrolled 50 AHF and 50 non-AHF patients discriminated through echocardiographic analysis and Framingham criteria and were matched by age and sex. Body composition was analyzed using a multifrequency BIA. Results: AHF patients demonstrated higher extracellular water (ECW)/total body water (TBW) compared with non-AHF patients ($0.412{\pm}0.017$ vs. $0.388{\pm}0.023$, p < 0.001). A significant difference of ECW/TBW between AHF patients and non-AHF patients was noted when the upper extremities, trunk, and lower extremities were analyzed (all p < 0.001, respectively). ECW/TBW was not different between patients with reduced ejection fraction (EF) and preserved EF along body compartments. The best cut-off value to predict AHF was > 0.412 at lower extremities with sensitivity and specificity of 0.780 and 0.960. The ECW/TBW of the lower extremities ($ECW/TBW_L$) was correlated with log B-type natriuretic peptide (BNP) levels (r = 0.603, p < 0.001) and also improved the net reclassification improvement and integrated discriminated improvement when added to log BNP level. Multivariate analysis revealed that $ECW/TBW_L$ > 0.412 had an independent association with AHF patients (p = 0.011). Conclusions: The $ECW/TBW_L$ was higher in patients with dyspnea caused by AHF than their counterparts and demonstrated an independent diagnostic implication. It may be a promising marker to diagnose AHF at bedside.