What is the primary purpose of PEEP in mechanical ventilation?

The primary purpose of PEEP (Positive End-Expiratory Pressure) in mechanical ventilation is to prevent the collapse of alveoli during exhalation. By maintaining a certain level of pressure in the airways at the end of expiration, PEEP helps keep the alveoli open, thereby improving gas exchange and oxygenation. This is particularly important in conditions such as ARDS (Acute Respiratory Distress Syndrome), where alveolar collapse can significantly impair lung function and oxygenation.

When PEEP is applied, it recruits collapsed or partially collapsed alveoli, increasing the surface area available for gas exchange. This leads to enhanced ventilation/perfusion matching, reduces shunting, and ultimately improves overall lung mechanics. The use of PEEP can also help decrease the work of breathing and improve lung compliance, which are crucial for patients experiencing respiratory distress.

Other options, while related to mechanical ventilation, do not accurately describe the primary role of PEEP. For example, while increasing lung volumes during inhalation is a function of other ventilatory settings, it is not the main effect of PEEP. Similarly, reducing the risk of aspiration and assisting in lowering respiratory rate are not direct functions of PEEP itself but rather pertain to overall mechanical ventilation strategies.