What is the most common side effect to PEEP?

The most common side effect of Positive End-Expiratory Pressure (PEEP) is hypotension, which can occur due to decreased venous return to the heart. This happens because PEEP increases intrathoracic pressure, reducing the pressure gradient that facilitates blood flow to the heart. Other potential side effects include barotrauma and reduced cardiac output, but hypotension is frequently noted in clinical settings.