What is a key purpose of using PEEP in mechanical ventilation?

Using PEEP (Positive End-Expiratory Pressure) in mechanical ventilation primarily serves the purpose of preventing atelectasis. This condition refers to the collapse of alveoli in the lungs, which can occur when there is insufficient pressure to keep them open during expiration. By applying PEEP, a maintained positive pressure in the airways at the end of expiration ensures that these alveoli remain open, improving gas exchange and enhancing oxygenation.

This approach is particularly beneficial in patients with conditions such as ARDS (Acute Respiratory Distress Syndrome), where the lung's compliance is compromised, and there is a tendency for alveoli to collapse. Maintaining some level of pressure prevents these collapses, thus promoting better ventilation-perfusion matching, reducing shunting of blood through non-ventilated areas, and improving overall lung mechanics.

In contrast, while it's possible for PEEP to influence tidal volume indirectly by improving lung recruitment, its primary intention is not to increase tidal volume but to keep the alveoli open. Similarly, PEEP does not directly increase the respiratory rate or decrease airway resistance. Therefore, its key purpose in mechanical ventilation distinctly aligns with preventing atelectasis, which significantly impacts patient outcomes in mechanical ventilation settings.