B-type natriuretic peptides for prediction and diagnosis of weaning failure from cardiac origin.

AIM: To evaluate and compare BNP and NT-proBNP concentrations to predict weaning failure from mechanical ventilation (MV) due to heart failure (HF) before a spontaneous breathing trial (SBT) and to identify HF as the cause of failure.
METHODS: Prospective, observational study in a university hospital. The sample included 100 patients on MV for over 48 h who underwent an SBT. Echocardiography and sampling for natriuretic peptides were performed immediately before and at the end of SBT. HF was diagnosed by pulmonary artery occlusion pressure >18 mm Hg or signs of elevated filling pressures in echocardiography.
RESULTS: Thirty-two patients failed the SBT, 12 due to HF and 20 due to respiratory failure (RF). Before SBT, BNP and NT-proBNP were higher in patients failing due to HF than RF or in successfully weaned patients. Cut-off values using ROC curve analyses to predict HF were 263 ng/L for BNP (p < 0.001) and 1,343 ng/L for NT-proBNP (p = 0.08). BNP and NT-proBNP increased significantly during SBT in patients failing due to HF. Increases in BNP and NT-proBNP of 48 and 21 ng/L, respectively, showed a diagnostic accuracy for HF of 88.9 and 83.3% (p < 0.001). BNP performed better than NT-proBNP for HF prediction (p = 0.01) and diagnosis (p = 0.009).
CONCLUSION: B-type natriuretic peptides, particularly BNP, can predict weaning failure due to HF before an SBT; increases in natriuretic peptides during SBT are diagnostic of HF as the cause of weaning failure. BNP performs better than NT-proBNP in prediction and diagnosis of HF.