Registered Respiratory Therapist (RRT-TMC) Practice Exam

The main idea is that PEEP works by keeping alveoli open at the end of expiration, which recruits collapsed airways and improves gas exchange. When alveoli stay inflated, more surface area is available for oxygen to diffuse into the blood, and ventilation-perfusion matching improves, leading to better arterial oxygenation. This is especially important in conditions like edema or ARDS where many alveoli tend to collapse or fill with fluid. Be aware that PEEP can raise intrathoracic pressure, which may reduce venous return and cardiac output—a potential downside rather than a benefit. It isn’t primarily about lowering work of breathing by reducing tidal volume; tidal volume is set separately, and while PEEP can influence overall respiratory mechanics, its principal beneficial effect is alveolar recruitment and improved oxygenation.