Most common symptoms and signs are dyspnea and hypoxemia, which progress to acute respiratory failure.
Common causes are pneumonia, sepsis, aspiration, and severe trauma.
Mortality is between 40% and 50%.
Low tidal volume, plateau-pressure-limited mechanical ventilation is the primary treatment that has been shown to reduce mortality. In severe acute respiratory distress syndrome (ARDS), neuromuscular blockade and prone positioning may improve clinical outcomes.
Complications include pneumothorax, ventilator-associated pneumonia, multiple organ failure, and pulmonary fibrosis with prolonged respiratory failure.
This topic covers ARDS in patients over the age of 12 years.
Acute respiratory distress syndrome (ARDS) is a noncardiogenic pulmonary edema and diffuse lung inflammation syndrome that often complicates critical illness. The diagnosis of ARDS is based on fulfilling three criteria:
• Acute onset (within 1 week)
• Bilateral opacities on chest x-ray
• PaO₂/FiO₂ (arterial to inspired oxygen) ratio of ≤300 on positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) ≥5 cm H₂O. 
If no risk factors for ARDS are present, then acute pulmonary edema as a result of heart failure should be ruled out.
History and exam
Professor of Medicine and Pathology, Microbiology and Immunology
Vanderbilt Medical Scholars Program
Division of Allergy, Pulmonary and Critical Care Medicine
Department of Medicine
Vanderbilt University School of Medicine
LW has received advisory board fees from Bayer, Quark, and CSL Behring and contractual research support to her institution from Global Blood Therapeutics, Boehringer Ingelheim, and CSL Behring.
Dr Lorraine Ware would like to gratefully acknowledge Dr Richard Fremont, a previous contributor to this topic.
Director of Medicine Critical Care Fellowship
Department of Anesthesia and Perioperative Care
University of California San Francisco
MAM declares that he has no competing interests.
Professor of Intensive Care Medicine
Royal Brompton Hospital
TE declares that he has no competing interests.
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