Introduction: Noninvasive ventilation (NIV) is considered as first line therapy in acute respiratory failure due to COPD exacerbations. However, some patients fail in responding to NIV and require intubation either in the early or later phase of the treatment. In this study, we wanted to find possible risk factors associated with early and late NIV failure.

Methods: Consecutive patients who required NIV support due to COPD exacerbation were prospectively included into study. NIV failure was defined as either need for intubation or death. NIV failed patients were divided (from the median) into two subgroups as early and late failure depending on the time of NIV failure.

Results: A total of 75 patients (median age 70 years, 62 male) were included. The median GCS was 15 and arterial blood gas values for pH, PaCO₂ and PaO₂ were 7.27 (7.20-7.32) and 77.0 (62.0-86.1) mmHg and 51.5 (42.3-64.1) mmHg respectively. NIV was successful in 45 and failed in 30 patients with a median of 2.5 days. NIV failed patients had prolonged transfer to ICU (p=0.04), lower GCS (p<0.01) and lower prealbumin levels (p=0.03). NIV failure was associated with increased mortality (70% vs 0; p<0.01). When compared to early NIV failure, late NIV failure (n=15) was associated with presence of acute kidney injury (AKI) on admission and development of nosocomial infection (p=0.04).

Conclusion: NIV failure was associated with an increased risk of in-hospital death. Delayed admission to ICU, poor neurologic status and low prealbumin levels were related with NIV failure; late NIV failure was associated with AKI on admission and nosocomial infection. These results might suggest the need for a careful follow-up patients whom initially respond well to NIV.