<prompt> A 64-year-old woman is admitted to the hospital with right lobar pneumonia and sepsis syndrome. She becomes progressively shorter of breath and hypoxemic requiring intubation and mechanical ventilation. Her repeat CXR in the intensive care unit now shows diffuse pulmonary infiltrates and a diagnosis of acute respiratory distress syndrome ARDS is made. Which of the following mechanisms is the most likely cause for the early exudative phase of ARDS?increased lung complianceincreased interstitial fibrosisincreased vascular permeability to fluid and proteinsdecreased pulmonary perfusion  <response>: The increased vascular permeability is the hallmark of the disease. Diagnostic criteria include acute onset, PaO2 FiO2 200 mm Hg regardless of positive end-expiratory pressure level, bilateral infiltrate on frontal CXR, and pulmonary artery occlusion pressure 18 mmHg or if not measured, no evidence of left atrial hypertension. 