Which position is used to promote lung expansion in ARDS?

• A. Lie flat
• B. Sit them up to promote lung expansion
• C. Prone position
• D. Trendelenburg

Answer: (B)

In ARDS, the way the lungs expand and the air reaches the alveoli depends a lot on body position, because gravity and chest wall mechanics change how air is distributed and how perfusion matches ventilation. The position that most effectively promotes lung expansion and improves oxygenation is turning the patient onto the stomach (prone position). In this posture, the posterior (often better-perfused) portions of the lung are better recruited, the heart and mediastinal structures press less on the lungs, and the distribution of pleural pressures becomes more even. That combination helps more alveoli stay open with each breath, reduces shunting, and improves gas exchange.

Lying flat tends to worsen atelectasis in the dependent areas, while a Trendelenburg position can hinder overall hemodynamics and isn’t used for lung recruitment. Sitting up can help with diaphragmatic movement and secretion clearance, but it doesn’t achieve the same level of posterior lung recruitment seen with prone positioning, especially in severe ARDS. That’s why prone positioning is the established approach to promoting lung expansion in ARDS.