1. enrollment criteria and clinical data collection: follow the principles of medical ethics, the development of inclusion and exclusion criteria, select 90 cases of ARDS patients, in the active treatment at the same time, according to the Berlin standard severity of the disease divided into mild group, moderate Group and severe group, according to the prognosis during hospitalization is divided into survival group and death group. BALF specimens were collected on the day of admission to detect the levels of NETs and alveolar macrophages. The acute and chronic health status scoring system Ⅱ (APACHEⅡ) and Murray acute lung injury score, blood routine, creatinine, urea nitrogen, fasting blood glucose, Item, mean arterial pressure, arterial blood gas analysis, oxygenation index; record the patient's mechanical ventilation time and other data;
2. Pearson linear correlation analysis of BALF in the content of NETs, alveolar macrophage coke death level was a positive correlation between the Spearman rank correlation analysis BALF in the NETs content and alveolar macrophage coke death level, APACHE Ⅱ, Murray score, creatinine, Urea nitrogen, fasting blood glucose and other indicators and ARDS severity was positively correlated;
3. To analyze the prognostic factors of different prognostic factors, to evaluate the content of NETs in BALF, the level of alveolar macrophage coke, APACHEⅡ and Murray scores were analyzed by receiver operator characteristic curve (ROC curve) Short - term survival outcome prognostic value.

Inclusion Criteria:

• ARDS patients diagnosis within 3 days
• Over 18 years old but no more than 75 years old

Exclusion Criteria:

• Severe thoracic open trauma
• Pulmonary embolism
• Severe cardiovascular and cerebrovascular disease
• Endocrine system diseases
• Coagulation dysfunction
• Liver and kidney failure
• Malignant tumors
• Cardiogenic pulmonary edema

Patients diagnosed with ARDS