ARDS

According to the Berlin Definition, what is the minimum PaO₂/FiO₂ ratio threshold that defines moderate ARDS?

A 38-year-old woman is admitted to the ICU following a motor vehicle accident with polytrauma. On day 3, she develops acute hypoxemic respiratory failure with bilateral pulmonary infiltrates and a PaO₂/FiO₂ ratio of 150 mmHg. ARDS is diagnosed. Which is the most common non-infectious cause of ARDS in trauma patients?

Regarding the diagnostic criteria, risk factors, and prognostic indicators in ARDS, all of the following are correct EXCEPT:

A 38-year-old woman with severe COVID-19 pneumonia is intubated on day 5 of illness. She is on Vt = 6 mL/kg IBW, PEEP = 12 cm H₂O, FiO₂ = 0.8, and sedation with propofol and fentanyl. Her PaO₂/FiO₂ ratio is 95 mmHg (severe ARDS). Chest X-ray shows diffuse bilateral consolidation. Hemodynamics are stable. What is the most appropriate next step in management?

A 38-year-old woman with sepsis secondary to aspiration pneumonia has been intubated for 4 days and meets Berlin criteria for moderate ARDS (PaO₂/FiO₂ = 150). Her clinical course has been complicated by persistent hypoxemia despite escalating PEEP. Which investigation is most useful to assess for occult complications and guide further management?