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

Abstract

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 ± 0.017 vs. 0.388 ± 0.023, p < 0.001). A significant difference of ECW/TBW between AHF patients and nonAHF 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/TBWL) 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/TBWL > 0.412 had an independent association with AHF patients (p = 0.011).

Conclusion: The ECW/TBWL 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.

Keywords: Dyspnea; Electric impedance; Heart failure; Natriuretic peptide, brain.

Figure 1.

Bio-impedance device (A) and an example of analysis (B). The portable multifrequency bio-impedance device (InBody S10, InBody Co. Ltd.) was adopted in this study. With this tool, the data of body composition could be acquired within a minute at bedside.

Figure 2.

Comparison of water distribution (A), and association between ECW/TBW and body compartments (B) among the non-dyspnea, non-AHF, and AHF groups. The AHF patients (red) and patients with non-AHF etiologies (blue) had similar TBW and ICW, while the patients with AHF had significantly more ECW. Segmental ECW/TBW was persistently higher in the AHF patients. Values for the non-dyspnea group (black) are also presented. AHF, acute heart failure; TBW, total body water; ICW, intracellular water; ECW, extracellular water.

Figure 3.

Receiver operating characteristics curve analysis. In receiver operating characteristics curve analysis, the AUC of ECW/TBW to predict acute heart failure were presented, according to body compartments. ECW, extracellular water; TBW, total body water; AUC, area under the curve; CI, confidence interval.

Figure 4.

Violin plots showing the distribution of ECW/TBW_L in patients with or without AHF. The density trace of violin plots shows the ECW/TBW_L, while the box plots inside represent the summary statistics. ECW/TBW_L, the ratio of extracellular water to total body water of lower extremities; AHF, acute heart failure.