Acute Respiratory Distress Syndrome

Abstract

Acute respiratory distress syndrome (ARDS) is a syndrome characterized by increased permeability pulmonary edema, lung inflammation, hypoxemia, and decreased lung compliance. Clinical criteria include bilateral opacities on chest imaging, hypoxemia with a PaO₂/F_IO₂ ratio < 300 mm Hg with positive end-expiratory pressure (PEEP) ≥ 5 cm H₂O, and the respiratory failure cannot fully be explained by cardiac failure or fluid overload. Causes of ARDS can be categorized into those resulting from direct injury to the lungs (e.g., pneumonia, aspiration, toxic inhalation, near-drowning) and those from indirect injury to the lungs (e.g., sepsis, trauma, pancreatitis, blood transfusions). Lung inflammation in ARDS causes alveolar injury, leaky pulmonary capillaries, exudation of proteinaceous fluid into alveoli, and alveolar collapse. Patients with ARDS often require mechanical ventilation because of the increased work of breathing from decreased lung compliance and impaired gas exchange.