Pulm| Acute Respiratory Distress Syndrome (ARDS)

2.14 Acute Respiratory Distress Syndrome (ARDS) Pulmonary system review for the USMLE Step 1 Exam Acute respiratory distress syndrome (ARDS) is an acute, diffuse, inflammatory form of lung injury that is life-threatening for patients. ARDS is a response from the lungs to severe injury, most commonly caused by sepsis, but can also be caused by pneumonia, trauma, drowning, toxin inhalation, and pancreatitis. The lung injury from sepsis causes systemic inflammation, damaging lung tissue and causing diffuse alveolar damage, reducing surfactant production and causing alveolar edema. Patients with ARDS will present with progressive cough, progressive dyspnea, and hypoxia, and usually deteriorate quickly, 12-24 hours after symptom onset. Diagnosis of ARDS is based on imaging findings of bilateral lung infiltrates seen as white-out on chest X-ray and ground glass opacities on CT, as well as a decreased Pao2/Fio2 ratio to less than 300. Patients with ARDS are placed on mechanical ventilation with low tidal volume and positive end expiratory pressure (PEEP) to keep the alveoli open at the end of the respiratory cycle. Treatment of ARDS involves addressing the underlying cause of the disease, such as sepsis or pneumonia.