What is the effect of PEEP on functional residual capacity (FRC)?

PEEP, or Positive End-Expiratory Pressure, plays a significant role in mechanical ventilation settings by maintaining a certain level of airway pressure at the end of expiration. This pressure effectively prevents the collapse of the alveoli, which are the tiny air sacs in the lungs where gas exchange occurs. By keeping these alveoli open, PEEP increases the volume of air remaining in the lungs at the end of expiration, known as the functional residual capacity (FRC).

Increasing FRC is beneficial because it helps improve lung compliance and oxygenation. By reducing the likelihood of alveolar collapse, not only does PEEP maintain a higher volume of aerated lung tissues, but it also enhances ventilation-perfusion matching, which is crucial for efficient gas exchange. Higher FRC contributes to a greater surface area for gas exchange, thereby improving overall respiratory function.

When considering the other choices, it's clear that they misrepresent the relationship between PEEP and FRC. PEEP does not decrease FRC; in fact, it is precisely designed to do the opposite – to prevent alveolar collapse. The notion that PEEP has no effect on FRC also disregards the well-established physiological benefits of PEEP in elevating lung volumes. Similarly, the claim that PEEP