The Lung Compliance Can Early Predict the Outcome of Postextubation Use of Non-invasive Ventilation in Patients with Acute Respiratory Failure

Objective: Non-invasive ventilation (NIV) has been increasingly used, and recent studies showed the potential application as post-extubation use in patients with acute respiratory failure. This study aims to identify the early determinants of the successful use of NIV in these patients. Material and Methods: We retrospectively reviewed data from consecutive patients with acute respiratory failure and receiving NIV after extubation in medical intensive unit of Veteran General Hospital, Chiayi branch from 2013, May 01 to 2014, August. 31. The demographic data, cause of respiratory failure, disease severity, and dynamic lung compliance after the use of NIV were recorded. In this study, dynamic lung compliance was recorded routinely at 2, 4, 6, 12, 24, and 48 hours after extubation. Failed use of NIV was defined as reintubated within 3 days. Results: A trend of increased airway secretion in failed-NIVpatients A total of 52 patients were enrolled, and 11 (21.2%) patients were classified as failed use of NIV. The basic data were similar between found between the successful and failed groups, including age (73.2±15.1 vs. 76.5±14.3 years, P=0.53), sex (M/F ratio, 31/10 vs. 6/5, P=0.26), and rapid shallow index (90.0±29.7 vs. 95.2±48.5, P=0.75) . But, in patients with failed-NIV, there is a trend of increased airway secretion although not reach the statistical power. Gradual decrease of lung compliance and minute ventilation in failed-NIV patients After the use of NIV, we found that initial lung compliance were similar between the two groups. But, lung compliance started to decline in failed groups as early at 6 hours after the use of NIV. Lower compliance (49.2±20.1 vs. 64.7± 18.8ml/cmH2O, P=0.03) and tidal volume (270.4±85.3 vs. 365.6±100.4 ml, P=0.01)were found in failed subjects compared to the successful subjects. Subsequently,decompensated decrease of minute ventilation (5.5±1.7 vs. 7.9±2.2 L/min, P=0.01)developed and patients were reintubated later. 6-hr compliance predicts the successful use of NIV By multivariate analysis, we identified that 6-hr compliance predicted the successful use of NIV (OR 0.963; 95% CI, 1.006-2.841; P=0.046). We compared the use of 2-hr, 6-hr, and 24-hr lung compliance, and found that 6-hr is a better predictor for successful use of NIV compared with 2-hr or 24hr compliance.Using 6-hr compliance=46.5 ml/cmH2O as cut point, the overall sensitivity, specificity, positive predict value, and negative predict value were 83.3%, 60%, 88.3%, and 50.0% respectively. These data suggested that 6-hr compliance was an early and sensitive predictor for the successful use of NIV in patients with respiratory failure after extubation. Conclusion: In conclusion, NIV is increasingly used as a weaning strategy, and the early predictor is critically needed. We found that early lung compliance just 6 hours after the use of NIV effectively predict the outcome of the use of NIV in patients with respiratory failure after extubation.