Acute Respiratory Distress Syndrome: Diagnosis and Management


Acute respiratory distress syndrome (ARDS) is noncardiogenic pulmonary edema that manifests as rapidly progressive dyspnea, tachypnea, and hypoxemia. Diagnostic criteria include onset within one week of a known insult or new or worsening respiratory symptoms, profound hypoxemia, bilateral pulmonary opacities on radiography, and inability to explain respiratory failure by cardiac failure or fluid overload. ARDS is thought to occur when a pulmonary or extrapulmonary insult causes the release of inflammatory mediators, promoting inflammatory cell accumulation in the alveoli and microcirculation of the lung. Inflammatory cells damage the vascular endothelium and alveolar epithelium, leading to pulmonary edema, hyaline membrane formation, decreased lung compliance, and decreased gas exchange. Most cases are associated with pneumonia or sepsis. ARDS is responsible for one in 10 admissions to intensive care units and one in four mechanical ventilations. In-hospital mortality for patients with severe ARDS ranges from 46% to 60%. ARDS often must be differentiated from pneumonia and congestive heart failure, which typically has signs of fluid overload. Treatment of ARDS is supportive and includes mechanical ventilation, prophylaxis for stress ulcers and venous thromboembolism, nutritional support, and treatment of the underlying injury. Low tidal volume and high positive end-expiratory pressure improve outcomes. Prone positioning is recommended for some moderate and all severe cases. As patients with ARDS improve and the underlying illness resolves, a spontaneous breathing trial is indicated to assess eligibility for ventilator weaning. Patients who survive ARDS are at risk of diminished functional capacity, mental illness, and decreased quality of life; ongoing care by a primary care physician is beneficial for these patients.

Acute respiratory distress syndrome (ARDS) is a rapidly progressive noncardiogenic pulmonary edema that initially manifests as dyspnea, tachypnea, and hypoxemia, then quickly evolves into respiratory failure. Because roughly one-half of intensive care units (ICUs) in the United States are not staffed with intensivists,1 many family physicians care for patients with ARDS. In addition, family physicians may take on the role of ICU physicians during times of unprecedented threats to the health care system and severe resource shortages.2

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Clinical recommendationEvidence ratingComments

When mechanical ventilation is required, patients with ARDS should be started at lower tidal volumes (6 mL per kg) instead of at traditional volumes (10 to 15 mL per kg).2527,29,30


Randomized controlled trial, Cochrane review, and expert guidelines

Higher positive end-expiratory pressure values (12 cm H2O) should be considered for initial mechanical ventilation in patients with ARDS.2527,32


Systematic review and expert guidelines

Prone positioning for 12 to 16 hours per day is recommended for patients with severe ARDS.2527,33


Meta-analysis and expert guidelines

Prophylaxis for venous thromboembolism should be given to all patients hospitalized with ARDS.41


Expert guideline

Enteral feeding should be initiated if a patient is anticipated to be on a ventilator for 72 hours or more.43


Expert guideline

Spontaneous breathing trials guided by a ventilator liberation (weaning) protocol should be initiated once a patient with ARDS begins to improve.28,52,53


Cochrane review and expert guidelines

ARDS = acute respiratory distress syndrome.

A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to

The Authors

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AARON SAGUIL, MD, MPH, FAAFP, is associate dean of regional education at the Uniformed Services University of the Health Sciences, San Antonio, Tex., and an associate professor in the Department of Family Medicine at F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Md....

MATTHEW V. FARGO, MD, MPH, is command surgeon of the 8th Theater Sustainment Command, Fort Shafter, Hawaii.

Published online May 15, 2020.

Address correspondence to Aaron Saguil, MD, MPH, FAAFP, Brooke Army Medical Center, Department of Medicine, 3551 Roger Brooke Dr., Fort Sam Houston, TX 78234 (email: Reprints are not available from the authors.

Author disclosure: No relevant financial affiliations.


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