Which statement accurately describes positive end-expiratory pressure (PEEP)?

Positive end-expiratory pressure (PEEP) is an essential aspect of mechanical ventilation, particularly for patients with Acute Respiratory Distress Syndrome (ARDS). PEEP works by maintaining a certain level of pressure in the airways at the end of expiration, which helps keep the alveoli (the tiny air sacs in the lungs) open and prevents them from fully collapsing during the breathing cycle.

When PEEP is applied, the increased end-expiratory lung volume prevents atelectasis (collapse of lung tissue) and optimizes gas exchange. By maintaining the alveoli open, more surface area is available for oxygen and carbon dioxide exchange, which is particularly critical for patients who may have compromised lung function.

The other statements do not accurately describe PEEP's effects. While PEEP does have a role in protecting lung function and supporting oxygenation, it is specifically significant for preventing alveolar collapse rather than for directly delivering air or oxygen or preventing lung damage overall while on a ventilator. Thus, the accurate statement is that PEEP effectively prevents the lung air sacs from collapsing during exhalation.