Which is a goal of PEEP?

• A. Recruitment of alveoli
• B. Improve oxygenation
• C. Improve FRC
• D. All of the above

Answer: (D)

PEEP works by keeping airways and alveoli open at the end of expiration, which directly supports three related goals. First, by preventing collapse of dependent units, it recruits previously derecruited or underinflated alveoli, increasing the number of units participating in gas exchange. Second, with more alveoli open and better ventilation-perfusion matching, arterial oxygenation improves. Third, maintaining positive pressure at end expiration raises the functional residual capacity, the lung volume available for gas exchange at the end of a breath. Together, these effects explain why improving recruitment, oxygenation, and FRC are all goals of PEEP. (Remember, balance is key—excessive PEEP can impair hemodynamics or cause overdistention.)