Changes in B-type Natriuretic Peptide and Related Hemodynamic Parameters Following a Fluid Challenge in Critically Ill Patients with Severe Sepsis or Septic Shock

CONTEXT: Severe sepsis or septic shock. AIMS: The aim of this study is to examine the effect of a fluid challenge on the B-type natriuretic peptide (BNP) and the hemodynamic state. SETTINGS AND DESIGN: This observational study was conducted in an intensivist-led academic, mixed medical-surgical Intensive Care Unit. SUBJECTS AND METHODS: Focused transthoracic echocardiogram, plasma BNP, and hemodynamic measurements were recorded at baseline and following a 500 ml fluid challenge in thirty patients. Independent predictors of the percentage (%) change in stroke volume (SV) were sought. Next, these independent predictors were assessed for a relationship with the percentage change in BNP. STATISTICAL ANALYSIS USED: Multiple linear regressions, Wilcoxon rank-sum test, t-test, and Pearson's correlation were used. Data analysis was carried out using SAS. The 5% significance level was used. RESULTS: Using a multiple regression models, the percentage increase in SV was independently predicted by the percentage increase in mean arterial pressure, left ventricular end-diastolic volume/dimension (LVEDV/LVEDd), ejection fraction, and a decrease in Acute Physiology and Chronic Health Evaluation II score (P < 0.0001). Preload, measured using LVEDV1 (before the fluid challenge) was significantly larger in the fluid nonresponders (%SV increase <15%) vs. the responders (%SV increase ≥15%). Finally, the percentage change in BNP was positively correlated with left ventricular size at end diastole LVEDd, r = 0.4, P < 0.035). CONCLUSIONS: An increase in BNP soon after a fluid challenge may have some predictive utility of a large LVEDd, which in turn can be used to independently predict the SV response to a fluid challenge.