What physiological change does PEEP primarily induce in the lungs?

PEEP, or Positive End-Expiratory Pressure, primarily improves lung compliance, which refers to the lung's ability to expand during inhalation. When PEEP is applied, it keeps the alveoli open at the end of expiration, preventing collapse and promoting better ventilation throughout the lung fields. This recruitment of previously collapsed or under-inflated alveoli increases the overall surface area available for gas exchange and enhances the elastic properties of the lungs.

By increasing lung compliance, PEEP allows for a more efficient tidal volume delivery with less effort from the respiratory muscles, reducing the work of breathing. This is particularly beneficial in conditions such as Acute Respiratory Distress Syndrome (ARDS) or other restrictive lung diseases, where lung compliance is decreased.

In contrast, the other options do not accurately reflect the effects of PEEP. While PEEP does not directly increase tidal volume, it can enhance effective ventilation without requiring larger tidal volumes. It does not decrease alveolar size; rather, it maintains or increases the size of open alveoli. Furthermore, PEEP typically reduces airway resistance by promoting better air distribution in the lungs, rather than increasing it. This makes an understanding of PEEP’s role in enhancing lung compliance particularly important for those involved in mechanical ventilation management