Flow-chart of the study. Among the 1,163 patients admitted for acute respiratory failure, 465 patients received NIV over a three-year period. After excluding 35 patients who received NIV with a “do not intubate” order, 430 received NIV of which 242 had acute hypercapnic respiratory failure and 188 had acute hypoxemic respiratory failure. After excluding 69 patients who received NIV for cardiogenic pulmonary edema and 6 patients without pulmonary infiltrates, 113 patients had non-hypercapnic acute hypoxemic respiratory failure. (ARDS, acute respiratory distress syndrome; NIV, Non-invasive ventilation).