Predictors of non-invasive ventilation failure in severe respiratory failure due to community acquired pneumonia

Non-invasive ventilation (NIV) has been used for acute respiratory failure to avoid endotracheal intubation and intensive care admission. Few studies have assessed the usefulness of NIV in patients with severe community acquired pneumonia (CAP). The use of NIV in severe CAP is controversial because there is a greater variability in success compared to other pulmonary conditions. We retrospectively followed 130 patients with CAP and severe acute respiratory failure (PaO2/FiO2 < 250) admitted to a Respiratory Monitoring Unit (RMU) and underwent NIV. We assessed predictors of NIV failure and hospital mortality using univariate and multivariate analyses. NIV failed in 26 patients (20.0%). Higher chest X-ray score at admission, higher heart rate after 1 hour of NIV, and a higher alveolar-arteriolar gradient (A-aDO2) after 24 hours of NIV each independently predicted NIV failure. Higher chest X ray score, higher LDH at admission, higher heart rate after 24 hours of NIV and higher A-aDO2 after 24 hours of NIV were directly related to hospital mortality. NIV treatment had high rate of success. Successful treatment is related to less lung involvement and to early good response to NIV and continuous improvement in clinical response.