Utility of respiratory ward‐based NIV in acidotic hypercapnic respiratory failure

Background and objective We sought to elicit predictors of in‐hospital mortality for first and subsequent admissions with acidotic hypercapnic respiratory failure ( AHRF ) in a cohort of chronic obstructive pulmonary disease patients who have undergone ward‐based non‐invasive ventilation ( NIV ), and identify features associated with long‐term survival. Methods Analysis of prospectively collected data at a single centre on patients undergoing NIV for AHRF between 2004 and 2009. Predictors of in‐hospital mortality and intubation were sought by logistic regression and predictors of long‐term survival by C ox regression. Results Initial p H exhibited a threshold effect for in‐hospital mortality at p H  7.15. This relationship remained in patients undergoing their first episode of AHRF . In both first and subsequent admissions, a p H threshold of 7.25 at 4 h was associated with better prognosis ( P  = 0.02 and P  = 0.04 respectively). In second or subsequent episodes of AHRF , mortality was lower and predicted only by age ( P  = 0.002) on multivariate analysis. Conclusions NIV could be used on medical wards for patients with p H  7.16 or greater on their first admission, although more conservative values should continue to be used for those with a second or subsequent episodes of AHRF .