[The value of N-terminal pro-B type natriuretic peptide in predicting the outcome of spontaneous breathing trials in elderly renal dysfunction patients].

OBJECTIVE:To investigate the value of N-terminal pro-B type natriuretic peptide (NT-proBNP) in predicting the outcome of spontaneous breathing trial (SBT) in ventilated elderly renal dysfunction patients. METHODS:The clinical data of patients who received mechanical ventilation in the Department of Critical Care Medicine of the First Affiliated Hospital of Guangzhou Medical University, Guangzhou Institute of Respiratory Disease from January 2011 to December 2014 were analyzed retrospectively. AU the patients conformed to the following criteria: age > 65 years, endogenous creatinine clearance rate (CCr) < 60 mL×min(-1)×1.73 m(-2), the duration of mechanical ventilation > 72 hours and undergone at least one SBT. The patients were assigned to a SBT success group and a SBT failure group according to the outcome of first SBT. The following factors were recorded: gender, age, the underlying disease [chronic obstructive pulmonary disease (COPD), heart failure (HF) and others], body mass index (BMI), serum pre-albumin (pre-ALB), and acute physiology and chronic health evaluation II (APACHE II) score, CCr and the concentration of the plasma NT-proBNP before SBT. Receiver operator characteristic curve (ROC) was plotted, and the predict value of NT-proBNP for the outcome of SBT in elder patients with kidney dysfunction was determined. RESULTS:A total of 58 patients with complete data were enrolled, with 41 cases in SBT success group, and 17 in SBT failure group. There were no significant differences in gender [male/female (cases): 26/15 vs. 13/4, χ (2) = 0.930, P = 0.335], age (years: 70.2±7.4 vs. 74.6±10.1, t = 0.833, P = 0.339), the stratification of underlying diseases [COPD/HF/COPD+HF/others (cases): 15/9/13/4 vs. 7/3/5/2, χ (2) = 0.242, P = 0.971], BMI (kg/m(2): 25.2±11.3 vs. 27.4±6.43, t = 1.038, P = 0.221), pre-ALB (mg/L: 201.0±13.2 vs. 189.0±7.6, t = 0.688, P = 0.519), and APACHE II score (12.2±3.2 vs. 13.5±6.3, t = 1.482, P = 0.147) and CCr (mL×min(-1)×1.73 m(-2): 51.3±7.7 vs. 54.2±6.4, t = 0.711, P = 0.487) before SBT between SBT success group and SBT failure group. The concentration of plasma NT-proBNP in SBT failure group was significantly higher than that of the SBT success group (μg/L: 4.162±1.128 vs. 2.284±1.399, t = 4.905, P = 0.000). The area under ROC curve for plasma NT-proBNP in predicting successful SBT among elder patients with kidney dysfunction was 0.878, with 95% confidence interval (95%CI) 0.786 - 0.970. The cut-off method was used, and it was identified that the concentration of NT-proBNP < 3.350 μg/L as a predictor for successful SBT, with sensitivity of 82.4%, specificity of 87.8%, positive prediction value of 88.1% and negative predictive value of 76.5%. CONCLUSIONS:The concentration of plasma NT-proBNP may increase in elderly kidney dysfunction patients undergoing ventilation, and NT-proBNP < 3.350 μg/L can serve as a good predictor for SBT success.