Potential Biomarkers and Pathogenic Mechanism for Reflux Aspiration-induced Lung Injury.

Inclusion Criteria: The patient is between 18-99 years old. The patient meets the diagnostic criteria for ARDS upon admission to the ICU or during hospitalization, and requires mechanical ventilation with endotracheal intubation. Within 24 hours of endotracheal intubation, bronchoscopy is performed for diagnostic or therapeutic purposes, and BALF is collected. PH, amylase, and cytokines are tested within 24 hours. The patient, legal guardian, or authorized patient representative must voluntarily sign an informed consent form approved by the corresponding institutional review board. If the patient signs the consent form, the person obtaining consent must ensure that the patient is in a sufficient condition to provide informed consent. Exclusion Criteria: Clinical diagnosis of left ventricular failure Lung cancer-primary or metastatic Hematologic malignancy Acute gastrointestinal bleeding precluding enteral feeding Severe immunosuppression, defined as cytotoxic therapy within 15 days or White blood cell count of 5000 7) Use of steroids: 0.25 mg/kg/day of prednisone (or an equivalent dose of corticosteroids) Use of nonsteroidal anti-inflammatory (including aspirin) drugs within the last 24 hrs Known to be HIV positive Moribond at entry Pregnancy or positive pregnancy test