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

• numbers of patients who met the intubation criteria [ Time Frame: 1 year ] [ Designated as safety issue: No ]
• the numbers of patients who are actually intubated [ Time Frame: 1 year ] [ Designated as safety issue: No ]

• inhospital mortalities [ Time Frame: 1 year ] [ Designated as safety issue: No ]
• intensive care unit mortalities [ Time Frame: 1 year ] [ Designated as safety issue: No ]

To assess the safety and efficacy of noninvasive positive pressure ventilation for patients with intro-pulmonary pulmonary acute lung injury and compare this with high-concentration oxygen therapy.

• Procedure: noninvasive positive pressure ventilation
  Patients in the NPPV group are ventilated using the CPAP or bilevel positive airways pressure S/T mode.
• Procedure: oxygen therapy
  In the control group, Venturi masks are used to maintain SpO2 at 92% to 96% by adjusting the oxygen flow rates.

• Experimental: NPPV
  Intervention: Procedure: noninvasive positive pressure ventilation
• Active Comparator: Control
  Intervention: Procedure: oxygen therapy

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.