Assessing lung fluid status using noninvasive bioelectrical impedance analysis in patients with acute heart failure: A pilot study

Background: Outpatient monitoring of pulmonary congestion in heart failure (HF) patients may reduce hospitalization rates. This study tested the feasibility of non-invasive high-frequency bioelectrical impedance analysis (HF-BIA) for estimating lung fluid status. Methods: This prospective study included 70 participants: 50 with acute HF (HF group) and 20 without HF (control group). All participants underwent a supine chest CT scan to measure lung fluid content with lung density analysis software. Concurrently, direct segmental multi-frequency BIA was performed to assess the edema index (EI) of the trunk, entire body, and extremities. Results: The correlation coefficients between lung fluid content and EI measured using HF-BIA were r = 0.566 (p < 0.001) and r = 0.550 (p < 0.001) for the trunk and whole body, respectively. In the HF group, the trunk EI (0.402 ± 0.015) and whole body EI (0.402 ± 0.016) were significantly higher than those of the control group (trunk EI, 0.383 ± 0.007; whole body EI, 0.383 ± 0.007; all p < 0.001). The lung fluid content was significantly higher in the HF than that in the control group (23.7 ± 5.3 vs. 15.5 ± 2.8%, p < 0.001). The log value of NT pro-BNP was significantly correlated with trunk EI (r = 0.688, p < 0.001) and whole-body EI (r = 0.675, p < 0.001) measured by HF-BIA, and the lung fluid content analyzed by CT (r = 0.686, p < 0.001). Conclusions: BIA-based EI measurements of the trunk and whole body significantly correlated with lung fluid content and NT pro-BNP levels. Non-invasive BIA could be a promising screening tool for lung fluid status monitoring in acute HF patients.