Related Experiment Video
Updated: Jul 1, 2026
Integration of Brain Tissue Saturation Monitoring in Cardiopulmonary Exercise Testing in Patients with Heart Failure
Published on: October 1, 2019
Correlation between impedance cardiography and B-type natriuretic peptide levels in dyspneic patients
Erika G Havelka1, Kathleen H Rzechula, Tyson O Bryant
1Department of Emergency Medicine, Advocate Christ Medical Center, Oak Lawn, Illinois, USA.
Insights
B-type natriuretic peptide (BNP) and impedance cardiography (ICG) showed limited correlation in diagnosing congestive heart failure (CHF). BNP offered slightly better diagnostic accuracy than ICG for CHF in the emergency department setting.
Area of Science:
- Cardiology
- Medical Diagnostics
- Biomedical Engineering
Background:
- Serum B-type natriuretic peptide (BNP) and impedance cardiography (ICG) are utilized in the Emergency Department (ED) for congestive heart failure (CHF) evaluation.
- The agreement between BNP and ICG data in CHF diagnosis remains uncertain.
Purpose of the Study:
- To assess the correlation between BNP levels and ICG parameters (cardiac index, systemic vascular resistance, thoracic fluid content) in ED patients with dyspnea.
- To compare the diagnostic accuracy of BNP and ICG in identifying CHF.
Main Methods:
- Prospective observational study of 54 patients presenting to the ED with dyspnea.
- Measured correlation between BNP and ICG parameters (CI, SVR, TFC) using Spearman's rank correlation.
- Constructed receiver operating characteristic (ROC) curves to compare diagnostic accuracy (Area Under the Curve - AUC) for CHF discharge diagnosis.
Main Results:
- Poor correlation observed between BNP and CI (ρ = -.07) and BNP and SVR (ρ = -.10).
- Moderate correlation found between BNP and TFC (ρ = .32, p=0.02).
- BNP demonstrated superior diagnostic accuracy (AUC = .77) compared to CI (AUC = .72) for CHF diagnosis.
Conclusions:
- Limited correlation between BNP and ICG parameters suggests they may provide dissimilar information for CHF assessment.
- Both BNP and cardiac index offer only fair diagnostic accuracy for CHF in this ED population.
Background:
Both serum measurements of B-type natriuretic peptide (BNP) and impedance cardiography (ICG) are used to evaluate patients for congestive heart failure (CHF) in the Emergency Department (ED), but the agreement between the data obtained by these two methods remains uncertain.
Study Objectives:
We sought to measure the correlation between BNP levels and ICG measurements in patients presenting to the ED with dyspnea, and compare the diagnostic accuracy of each method in diagnosing CHF.
Methods:
We performed a prospective observational study of a convenience sample of patients presenting to the ED with dyspnea and being evaluated for CHF as a cause of their symptoms. An ICG measurement was obtained on each patient and the correlation between BNP level and the ICG parameters cardiac index (CI), systemic vascular resistance (SVR), and thoracic fluid content (TFC) was measured. To further quantify the diagnostic accuracy of ICG and BNP, we then constructed receiver operating characteristic curves based on discharge diagnosis of CHF and compared the area under the curve (AUC) of each test.
Results:
Out of 54 patients enrolled, correlation was poor between BNP and CI (Spearman's ρ = -.07, p = 0.64) and between BNP and SVR (Spearman's ρ = -.10, p = 0.46), but moderate between BNP and TFC (Spearman's ρ = .32, p = 0.02); a wide degree of scatter was seen in all correlations. BNP levels showed the best diagnostic accuracy for a discharge diagnosis of CHF, with an AUC of .77 (95% confidence interval .59-.95), whereas CI had an AUC of .72 (95% confidence interval .55-.88).
Conclusion:
We found limited correlation between BNP levels and ICG parameters, suggesting that, in our population, the two tests may not consistently give similar information. BNP level and CI both provided only fair diagnostic accuracy for discharge diagnosis of CHF.
