Which factor helps prevent alveolar collapse and promotes gas exchange when ventilating a patient?

• A. Increases alveolar collapse
• B. Decreases alveolar ventilation
• C. Prevents alveolar collapse and recruits alveoli
• D. No effect on gas exchange

Answer: (C)

Preventing alveolar collapse and actively recruiting alveoli is central to effective ventilation. When alveoli stay open, the surface area for gas exchange increases and the ventilation-perfusion relationship improves, leading to better oxygen uptake and carbon dioxide removal. In mechanical ventilation, applying positive end-expiratory pressure (PEEP) helps keep alveoli open at the end of exhalation, reducing atelectasis, while recruitment maneuvers temporarily raise pressures to reopen collapsed units. Together, these strategies prevent collapse and recruit more alveoli, which enhances gas exchange. Choices that describe increasing collapse or decreasing ventilation would worsen gas exchange, and stating no effect would be incorrect.