What is a primary purpose of prone positioning in ARDS management?

• A. Reduces sedation requirements
• B. Improves ventilation-perfusion matching and oxygenation
• C. Increases infection risk
• D. Shortens ICU stay

Answer: (B)

Prone positioning improves ventilation-perfusion matching and oxygenation by making lung inflation more uniform and recruiting the dorsal (back) regions that are often collapsed in ARDS when lying on the back. When patients are prone, the heart and abdominal contents exert less compression on the dorsal lung, allowing better alveolar expansion there. This leads to more even distribution of air, reduction in shunt, and perfusion remains aligned with the better-ventilated areas, so blood flow meets better oxygenation. In addition, this setup can decrease ventilator-induced lung injury by spreading mechanical stress more evenly across the lung. While prone positioning can have other effects, its primary purpose is to boost oxygenation through improved V/Q matching, not to reduce sedation, increase infection risk, or shorten ICU stay.