What is the main purpose of CPAP therapy?

The main purpose of Continuous Positive Airway Pressure (CPAP) therapy is to maintain airway pressure above atmospheric levels. This positive pressure helps keep the airways open during both inhalation and exhalation, preventing them from collapsing, especially during sleep, which is crucial in conditions like obstructive sleep apnea. By ensuring that the airway remains patent, CPAP improves oxygenation and can significantly reduce the frequency of apnea episodes, ultimately enhancing overall respiratory function.

The other choices, while relevant to respiratory physiology, do not accurately capture the primary intention of CPAP therapy. For example, decreasing airway resistance during exhalation is a secondary effect of maintaining airway pressure but not the main purpose. Inducing nocturnal hypoxia contradicts the objectives of CPAP, as it seeks to prevent such conditions. Similarly, treating metabolic acidosis is unrelated to the direct purpose of CPAP, which focuses on maintaining airway patency rather than addressing metabolic issues.