with appropriate inspired oxygen concentrations, NPPV would prevent intubation and hence avert the poor outcome associated with the need of invasive ventilation in patients with ALI/ARDS.

Noninvasive positive-pressure ventilation (NPPV) is increasingly being used in the care of patients suffering acute respiratory failure. High-level evidence supports the use of NPPV to treat exacerbation of chronic obstructive pulmonary disease (COPD). More recently, NIV has shown to reduce the need for intubation in selected groups of patients with severe cardiogenic pulmonary edema, immunosuppression, and respiratory failure after lung resection. In their subgroup analysis of the five randomized control trials, however, patients with acute lung injury (ALI) or ARDS still couldn't avoid intubation and death even treated with NPPV. Till now, there has been no randomized controlled study of NPPV in patients with ALI or ARDS. We hypothesized that in patients with ALI/ARDS, early use of NPPV, providing appropriate inspired oxygen concentrations, would prevent intubation as the primary end-point variable, hence avert the poor outcome associated with the need of invasive ventilation. Accordingly, we conducted a prospective, randomized controlled trial to assess the efficacy of NPPV compared with a standard regime consisting of high-concentration oxygen therapy.

Inclusion Criteria:

• Meet the ALI/ARDS criteria

Exclusion Criteria:

• Age > 85
• pH < 7.35 or PaCO2 >50mmHg
• Glasgow Coma Scale (GCS)<11
• Airway or facial deformity
• Pneumothorax or pneumomediastinum
• Unable to spontaneously clear secretions from their airway
• Respiratory arrest
• Shock or 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
• Severe ventricular arrhythmia or active myocardial ischemia
• Severe organ dysfunction (including gastrointestinal hemorrhage, disseminated intravascular coagulation, hepatic and renal dysfunction, SOFA score>1)
• End-stage patients who are expected to survive less than six months
• Severe abdominal distension
• Refuse to receive NPPV
• Unable to cooperate with the application of NPPV