Early Use of Noninvasive Positive Pressure Ventilation for Intro-pulmonary Acute Lung Injury

Inclusion Criteria: 1. acute onset; 2. a clinical presentation of respiratory distress; 3. arterial oxygen tension/inspired oxygen fraction (PaO2/FIO2) \< 300 mmHg but \> 200 mmHg while breathing oxygen delivered by a conventional Venturi device at a maximum concentration (50%); 4. presence of bilateral pulmonary infiltrates on posteroanterior chest radiograph; 5. no evidence of left heart failure as assessed by echocardiography and/or a pulmonary artery wedge pressure of \<18 mm Hg. 6. the cause of ALI is consider to be intro-pulmonary. Exclusion Criteria: 1. age \<18 yrs; 2. Glasgow Coma Scale \< 11; 3. airway or facial injury; 4. pneumothorax or pneumomediastinum; 5. unable to spontaneously clear secretions from the airways; 6. cardiogenic shock or severe hemodynamic instability (systolic blood pressure \<90 mmHg associated with decreased urinary output (\<20 mL.h-1) despite fluid repletion and use of vasoactive agents) of other causes; 7. severe ventricular arrhythmia or unstable myocardial ischemia; 8. severe organ dysfunction (Sequential Organ Failure Assessment score \> 3); 9. end-stage patients who were expected to survive \< 6 months; 10. severe abdominal distension; 11. refusal to receive NPPV; 12. the cause of ALI is consider to be extrapulmonary; 13. unable to cooperate with NPPV application; 14. active upper gastrointestinal bleeding.