Acute Respiratory Distress Syndrome: Pathophysiology, Diagnosis, and Contemporary Management

Acute respiratory distress syndrome (ARDS) is a heterogeneous, life-threatening form of acute hypoxemic respiratory failure caused by diffuse inflammatory injury to the lungs. Increased permeability of the alveolar–capillary barrier allows protein-rich fluid to enter the interstitium and alveoli, impairing gas exchange and reducing functional lung volume. Common precipitating conditions include pneumonia, sepsis, aspiration, trauma, and pancreatitis. Diagnosis is clinical and depends on the acute time course, oxygenation impairment, bilateral pulmonary opacities, and assessment that respiratory failure is not primarily explained by cardiac failure or fluid overload. The 2023 global consensus definition broadened recognition by including selected patients receiving high-flow nasal oxygen, permitting lung ultrasound as an imaging option, and adapting oxygenation assessment for settings with limited resources. Management remains predominantly supportive: treat the underlying cause, use lung-protective ventilation, consider prolonged prone positioning in severe disease, individualize positive end-expiratory pressure, and avoid unnecessary fluid accumulation after shock has resolved. Outcomes vary with disease severity, comorbidities, and access to timely critical care. Survivors may experience physical, cognitive, and psychological sequelae, making rehabilitation and follow-up important. This narrative review summarizes core mechanisms, recognition, treatment principles, complications, and current research priorities.