B-Type Natriuretic Peptide: A Predictor for Mortality, Intensive Care Unit Length of Stay, and Hospital Length of Stay in Patients With Resolving Sepsis

Abstract

BACKGROUND B-type natriuretic peptide (BNP) is a hormone secreted by cardiomyocytes in response to myocardial ischemia, increased ventricular wall tension, and overload. BNP is utilized as a diagnostic and prognostic marker in congested heart failure (CHF). Its prognostic value in sepsis is unknown. The aim of this study is to determine if BNP correlates with increased in-hospital mortality for septic patients. METHODS This was a retrospective study of 505 patients admitted for sepsis or severe sepsis or septic shock during the period of January 2013 and August 2014. Patients that received > 3 L of intravenous fluids on presentation were included. Intensive care unit length of stay (ICULOS), hospital length of stay (HLOS) and in-hospital mortality were measured. Mean BNP level was calculated and compared to ICULOS and HLOS and in-hospital mortality. Controlled variables included ejection fraction (measured by echocardiogram within 6 months of presentation), glomerular filtration rate (calculated by Cockroft-Gault equation), patient demographics, and lactic acid trends. Exclusion criteria were no echocardiogram within 6 months of admission, no BNP levels on admission, and no repeat lactate or rising lactate levels within 24 h to indicate worsening sepsis. RESULTS Patients' mean BNP with in-hospital mortality was 908 pg/mL as compared to mean BNP of 678 pg/mL in survivors. T-test comparisons were statistically significant (P = 0.0375). The Kaplan-Meier curve for BNP as a predictor for in-hospital mortality showed that for the first 25 days, patients with BNP higher than 500 pg/mL had a higher mortality than patients with BNP lower than 500 pg/mL. When comparing HLOS, there is a statistically significant correlation (P = 0.0046). A similar scatter plot was prepared for ICULOS which showed there was a weak positive correlation (r = 0.199). CONCLUSION Septic patients with in-hospital mortality had an average BNP of 908 pg/mL and statistically significant higher HLOS.