New insights into the mechanisms involved in B-type natriuretic peptide elevation and its prognostic value in septic patients

Abstract

IntroductionElevated plasma B-type natriuretic peptide (BNP) levels in patients with critical sepsis (severe sepsis and septic shock) may indicate septic cardiomyopathy. However, multiple heterogeneous conditions may also be involved in increased BNP level. In addition, the prognostic value of BNP in sepsis remains debatable. In this study, we sought to discover potential independent determinants of BNP elevation in critical sepsis. The prognostic value of BNP was also evaluated.MethodsIn this observational study, we enrolled mechanically ventilated, critically septic patients requiring hemodynamic monitoring through a pulmonary artery catheter. All clinical, laboratory and survival data were prospectively collected. Plasma BNP concentrations were measured daily for five consecutive days. Septic cardiomyopathy was assessed on day 1 on the basis of left and right ventricular ejection fractions (EF) derived from echocardiography and thermodilution, respectively. Mortality was recorded at day 28.ResultsA total of 42 patients with severe sepsis (N = 12) and septic shock (N = 30) were ultimately enrolled. Daily BNP levels were significantly elevated in septic shock patients compared with those with severe sepsis (P ≤0.002). Critical illness severity (assessed by Acute Physiology and Chronic Health Evaluation II and maximum Sequential Organ Failure Assessment scores), and peak noradrenaline dose on day 1 were independent determinants of BNP elevation (P <0.05). Biventricular EFs were inversely correlated with longitudinal BNP measurements (P <0.05), but not independently. Pulmonary capillary wedge pressures (PCWP) and volume expansion showed no correlation with BNP. In septic shock, increased central venous pressure (CVP) and CVP/PCWP ratio were independently associated with early BNP values (P <0.05).Twenty-eight-day mortality was 47.6% (20 of 42 patients). Daily BNP values poorly predicted outcome; BNP on day 1 > 800 pg/ml (the best cutoff point) fairly predicted mortality, with a sensitivity%, specificity% and area under the curve values of 65, 64 and 0.70, respectively (95% confidence interval = 0.54 to 0.86; P = 0.03). Plasma BNP levels declined faster in survivors than in nonsurvivors in both critical sepsis and septic shock (P ≤0.002). In septic shock, a BNP/CVP ratio >126 pg/mmHg/ml on day 2 and inability to reduce BNP <500 pg/ml implied increased mortality (P ≤0.036).ConclusionsThe severity of critical illness, rather than septic cardiomyopathy, is probably the major determinant of BNP elevation in patients with critical sepsis. Daily BNP values are of limited prognostic value in predicting 28-day mortality; however, fast BNP decline over time and a decrease in BNP <500 pg/ml may imply a favorable outcome.

The role of brain natriuretic peptide in predicting renal outcome and fluid management in critically ill patients

“…11,12 Septic patients with poor renal outcomes also had elevated BNP levels at the beginning of their ICU stay (Figure 3). Because volume resuscitation is an important treatment for sepsis, the International Surviving Sepsis Campaign Guidelines Committee recommends fluid management to achieve a target CVP level.…”

“…Furthermore, many investigators have reported an association between the absolute BNP level and mortality in critically ill patients. 11,12 Therefore, our hypothesis was that the BNP level could also predict renal outcome and it has the potential to be a convenient cost-effective marker for fluid management in critically ill patients. The first aim of our study was to specify the association between the delta-BNP level and patient outcomes (i.e., AKI occurrence, recovery, and mortality).…”

Assessment of acute lung injury/acute respiratory distress syndrome using B-type brain natriuretic peptide

“…In patients with sepsis, a higher BNP level indicates a worse prognosis. 17 BNP levels are similar in patients with septic shock and cardiac emergencies; therefore BNP cannot be used to differentiate cardiac and septic shock. 18 BNP could also help determine the optimum time for weaning from mechanical ventilation: Mekontso-Dessap et al 19 reported that among 102 patients undergoing ventilation weaning, patients who failed the weaning or who had successful ventilation weaning but failed extubation had a significantly higher BNP level than patients with successful ventilation weaning and extubation.…”

The Optimal Cut-off Value of Plasma BNP to Differentiate Heart Failure in the Emergency Department in Japanese Patients with Dyspnea

“…Our previous report showed that inflammation increases the plasma BNP level (24). In septic patients, the severity of the illness is the main determinant of the BNP level, rather than cardiac function (25).…”