How does CPAP affect the patient’s work of breathing?

Continuous Positive Airway Pressure (CPAP) is a therapeutic modality commonly used in critical care settings, particularly for patients with respiratory distress or conditions such as obstructive sleep apnea, pulmonary edema, or acute respiratory distress syndrome (ARDS). The primary mechanism through which CPAP functions is by maintaining a constant positive pressure in the airways during both inspiration and expiration, which has several beneficial effects on a patient’s work of breathing.

By providing this constant positive airway pressure, CPAP helps to keep the alveoli open, thereby increasing functional residual capacity and enhancing gas exchange. This reduces the effort required by the patient to inhale and maintain adequate ventilation. Essentially, CPAP decreases the amount of negative pressure that the respiratory muscles must generate to draw air into the lungs, thus alleviating the respiratory muscle strain and making it easier for patients to breathe.

Moreover, CPAP enhances oxygenation by preventing alveolar collapse, improving ventilation-perfusion matching, and facilitating better overall oxygen delivery to the tissues. The reduction in the work of breathing not only contributes to improved comfort for the patient but also decreases the risk of fatigue related to respiratory effort.

In contrast to the correct explanation, other possible impacts of CPAP—such as increasing the work of breathing or having no effect—do