Prone positioning is recommended in which clinical scenario?

• A. Severe ARDS with refractory hypoxemia despite optimal ventilation
• B. Mild ARDS with good oxygenation
• C. Post-extubation respiratory failure
• D. Stable ARDS without hypoxemia

Answer: (A)

Prone positioning is used to boost oxygenation in severe ARDS by improving the distribution of ventilation and reducing shunt. When a patient lies on their back, the dorsal lung areas become compressed and poorly ventilated, while the ventral regions are relatively overstretched. Turning the patient prone unloads dorsal structures, promotes recruitment of dependent alveoli, and leads to more uniform pleural pressures and ventilation. This can markedly improve oxygenation and, in well-selected patients, has been shown to reduce mortality when used for extended periods alongside protective ventilation.

In the scenario described, oxygenation remains poor despite optimal protective ventilation and adequate PEEP—this is precisely when proning offers the most benefit. The benefits are greatest in severe ARDS with refractory hypoxemia, making this the best context for prone positioning.

In milder ARDS with good oxygenation, the risks and resource use of proning aren’t justified by a limited or uncertain benefit. Post-extubation respiratory failure isn’t an ARDS scenario needing prone positioning, and stable ARDS without hypoxemia doesn’t require it either.