In ARDS, prone positioning is most beneficial for which scenario?

• A. Mild ARDS with near-normal oxygenation
• B. Moderate-to-severe ARDS with persistent hypoxemia despite optimized ventilation
• C. ARDS due to cardiogenic edema with good response to diuresis
• D. Recovery phase after mechanical ventilation

Answer: (B)

Prone positioning improves oxygenation in ARDS by redistributing ventilation and perfusion, recruiting dorsal lung regions, and reducing shunt. It provides the most benefit when oxygenation remains severely impaired despite optimized lung-protective ventilation with adequate PEEP. In moderate-to-severe ARDS with persistent hypoxemia, turning to the prone position can markedly improve oxygenation and may reduce mortality. It’s less helpful in mild ARDS where oxygenation is near normal, and in ARDS from cardiogenic edema where addressing fluid overload is the main issue. In the recovery phase, the focus is typically on weaning rather than using proning to boost oxygenation.