ARDS

Acute Respiratory Distress Syndrome (ARDS) is a severe, diffuse form of acute lung injury characterized by refractory hypoxemia, bilateral pulmonary infiltrates, and decreased lung compliance — NOT caused by heart failure. ARDS carries a mortality rate of 35–46% and requires ICU-level care. Survivors often have long-term functional and cognitive impairments. Berlin Definition (2012) — required for diagnosis: - Onset within 1 week of a known clinical insult or new/worsening respiratory symptoms - Bilateral chest infiltrates on imaging (not explained by effusion, atelectasis, or nodules) - Respiratory failure NOT explained by cardiac failure or fluid overload (echocardiogram or BNP to exclude) - PaO₂/FiO₂ ratio (P/F ratio) < 300 mmHg on ≥ 5 cmH₂O PEEP/CPAP - Mild ARDS: P/F 200–300 - Moderate ARDS: P/F 100–200 - Severe ARDS: P/F < 100 Common triggers: Pneumonia (most common) > aspiration > sepsis > trauma/pulmonary contusion > pancreatitis > transfusion (TRALI) > drowning > inhalation injury. On the exam, writers often pair stable-sounding options with unstable data—notice the mismatch before you commit. If the stem names a license or role, reread that line; scope errors...