Figure 1).

Flow of patients through each stage of the study inclusion procedure. From 2003 to 2005, 452 patients needed intubation for acute respiratory failure, of which 377 were not included (exclusion rate = 83%). Of the 75 patients recruited, 12 were not included in the final analysis, with the remaining patients assigned to the final groups: Zero end-expiratory pressure (ZEEP) (n=33) and positive end-expiratory pressure (PEEP) (n=30). MICU Medical intensive care unit; MV Mechanical ventilation; NIV Noninvasive ventilation