Objective: Noninvasive ventilation (NIV) is a common practice in acute hypercapnic respiratory failure (AHRF) because of exacerbation of chronic obstructive pulmonary disease (COPD). However, a recent study has shown that patients who require invasive mechanical ventilation (IMV) after failure of NIV experience high mortality rates (up to 30%). Therefore, the aim of this study is to determine the parameters, specifically for emergency department (ED) presentation, associated with the transition from NIV to IMV because of NIV failure. Patients and methods: This is a 4-year retrospective cohort study in the EDs of two Dutch hospitals. International Classification of Disease codes were used to identify 139 COPD patients treated with NIV. Those with AHRF (pH limits: 7.25–7.35), a full resusc...