Determinants of In-Hospital Mortality of Patients Receiving Ward-Based Non-invasive Ventilation for Acute Hypercapnic Respiratory Failure

Abstract

Introduction: Door-to-mask time is a quality metric for Non-Invasive Ventilation (NIV) treatment that is applicable across the United Kingdom. This study examined the efficacy of this metric in predicting in-hospital mortality, alongside other variables including maximum IPAP, age, and degree of acidosis after rigorous infection control measures were introduced during COVID-19 pandemic that led to substantial delays in the provision of NIV treatment. Methods: All acute NIV applications for hypercapnic respiratory failure (AHRF) pre- and post-pandemic were included in this study (April – December 2019 and April – December 2021). Mann-Whitney U test and Chi-squared test were used for continuous and categorical variables, respectively. ANOVA test was used for the analysis of variance of mean door-to-mask time and mean maximum IPAP, and logistic regression was used to predict in-hospital death adjusted odds ratios across both cohorts combined. Results: From 2019 to 2021 total patients receiving NIV decreased by 26.2% (83 vs 45). There was not a significant difference in patients age across cohorts (p=0.93). Indications for NIV treatment was not significantly different, the majority received NIV treatment for COPD 87 (66.9%) vs 63 (65.6%) in 2019 and 2021, respectively. Door-to-mask time was significantly increased, 5.45 to 10.85 hours (p<0.001). However, in-hospital deaths were not significantly different, 27 (20.8%) vs 28 (29.2%) (p=0.15). Age and degree of acidosis affected significantly in-hospital mortality, odds ratio (95% CI), 1.037 (1.01, 1.07) (p=0.02) and 0.009 (0.00, 0.70) (p=0.03), respectively. However, door to mask time did not significantly affect odds ratio of in-hospital mortality, 1.004 (1.00, 1.01), (p=0.07). Prolonged door-to-mask time and lower maximum IPAP were associated with higher in-hospital mortality, (p=0.045) and (p=0.048), respectively. Conclusion: Within this cohort, age and degree of acidosis were independent predictors of in-hospital mortality. However, door-to-mask time was not a strong predictor of in-hospital mortality, despite the association observed between prolonged door-to-mask times and higher mortality rates. Hence further research on door-to-mask time is necessary to explore its association with increased in-hospital mortality.