ARDS is characterized by which of the following features?

• A. Acute onset of bilateral, noncardiogenic infiltrates and respiratory failure due to cytokine-mediated injury to the pulmonary parenchyma
• B. Chronic cough with wheeze and mucus plugging
• C. Unilateral infiltrate with cardiogenic edema
• D. Pulmonary embolism causing sudden death

Answer: (A)

ARDS is an acute, inflammatory injury to the lung that causes noncardiogenic pulmonary edema and severe hypoxemic respiratory failure. The hallmark is an abrupt onset, within a week of a precipitating event, with bilateral infiltrates on imaging that are not explained by heart failure or fluid overload. The injury disrupts the alveolar-capillary barrier, leading to increased permeability, edema fluid flooding the alveoli, and formation of hyaline membranes, all driven by cytokine-mediated damage to the pulmonary parenchyma. This pathophysiology explains why respiratory failure occurs despite the absence of left heart failure.

The other scenarios don’t fit ARDS findings: a chronic cough with wheeze points to chronic airway disease like asthma or COPD; a unilateral infiltrate with cardiogenic edema suggests edema from heart failure rather than diffuse noncardiogenic injury; pulmonary embolism can cause sudden death or acute symptoms but does not produce the bilateral noncardiogenic infiltrates characteristic of ARDS.