The Predictive Value Of NT-proBNP And Transpulmonary Thermodilution Measurements For Weaning Outcomes Of Critically-ill Patients With Mechanical Ventilation

Objective:To evaluate the predictive value of NT-proBNP and transpulmonary thermodilution measurements for weaning outcomes of critically-ill patients who are difficult to wean from mechanical ventilation.Methods:From January2013to February2014, a prospective study was conducted in adult patients who had been ventilated for more than24hours. Each of patients received an femoral-anterior internal catheter and hemodynamic parameters were monitored through a pulse indicator continuous cardiac output (PiCCO) device. Patients who met the criteria of2001Ameraican weaning guidelines initiated spontaneous breathing trial (SBT) and then extubated if successfully passing SBT. The fluid balance, results of arterial blood gas, serum levels of NT-proBNP, and results of transpulmonary thermodilution measurements were compared between patients with different SBT outcomes and between patients with different weaning outcomes. Afterwards, their predictive values in SBT outcomes and weaning outcomes were evaluated.Results:A total of34patients were enrolled in the study, including20(58.8%) men and14(41.2%) women, with an average APACHE Ⅱ score of21.6±1.4, and their median duration of mechanical ventilation was67.5(39,528) hours. Based on the SBT outcomes, there were28(82.4%) patients who successfully passed SBT and6(17.7%) patients who failed to pass SBT. The following parameters turned out to be significant predictors for SBT outcomes:the24-hours’ fluid balance before SBT [area under the ROC curve (AUC)=0.815±0.107, P=0.017], the daily fluid balance before SBT (AUC=0.940±0.040, P=0.001), the pre-SBT serum level of NT-proBNP (AUC=0.777±0.095, P=0.036), the post-SBT serum level of NT-proBNP (AUC=0.875±0.060, P=0.004), ANT-proBNP (AUC=0.964±0.032, P<0.001), AGEDVI (AUC=0.818±0.091, P=0.016), and the pulmonary vascular permeability index (PVPI)(AUC=0.905±0.061, P=0.002). Based on the weaning outcomes,16(47.1%) patients successfully weaned from the mechanical ventilation over48hours after extubation, while18patients (52.9%) failed. Four parameters were significant predictors for the weaning outcomes, including the daily fluid balance before SBT (AUC=0.733±0.090, P=0.021), AGEDVI (AUC=0.714±0.088, P=0.034), the extravascular lung water index (EVLWI)(AUC=0.799±0.076, P=0.003), and PVPI (AUC=0.873±0.058, P<0.001).Conclusions:Compared with NT-proBNP and other traditional volumetric parameters, transpulmonary thermodilution measurements show a significantly higher predictive value for weaning outcomes of patients with mechanical ventilation, especially of those with cardiogenic respiratory failure.