Variables predictive of outcome in patients with acute hypercapneic respiratory failure treated with noninvasive ventilation

Objective: To assess results with NIV in acute hypercapneic respiratory failure and to identify outcome predictors. Methods: This was a retrospective observational study on consecutive patients presenting with acute type II respiratory failure and meeting criteria for NIV use over a 5 year period. Patients presenting with haemodynamic instability, inability to protect their airway, malignant arrhythmias and recent oesophageal surgery were excluded. Univariate and Multivariate regression analysis was used to determine the impact on survival. A p value of < 0.05 was considered statistically significant. Software used was SPSS 14. Results: Total numbers of patients included were 119; 52.9% were males. Mean age was 63.4 ± 11.9 years. Overall Survival to discharge rate was 76.5%, intubation rate was 12.6% and mean length of stay was 11.4 ± 10.9 days. Statistically significant improvements were observed in the pH and PaCO2 at 24 hours and 48 hours compared to baseline (7.28 v/s 7.37, p<0.001; 74.2 v/s 65, p<0.001). On multivariate regression analysis, sepsis at admission predicted mortality (adjusted Odds ratio 26.4; 95% CI 2.3, 304, p < 0.009). A serum HCO3> 35 Meq/L (adjusted Odds ratio 0.9; 95% CI 0.83, 0.98, p < 0.015) identified those less at risk for intubation. Conclusion: NIV was found to be both safe and effective in the management of acute hypercapneic respiratory failure. Sepsis and serum HCO3 at admission identified patients having poor outcomes.