How does CPAP improve oxygenation?

CPAP, or Continuous Positive Airway Pressure, improves oxygenation primarily by enhancing the correction of ventilation-perfusion (V/Q) mismatch. This occurs due to the continuous pressure delivered by CPAP that helps keep the airways open, particularly in patients with conditions like obstructive sleep apnea or those suffering from acute respiratory distress.

When the airways are kept open, it ensures that collapsed or partially collapsed alveoli can reinflate, facilitating better ventilation to those areas of the lung. This improved ventilation allows for a more effective exchange of oxygen and carbon dioxide. Furthermore, by ensuring that the alveoli remain open, CPAP increases functional residual capacity (FRC), which is the volume of air that remains in the lungs after normal expiration. An increased FRC improves the overall gas exchange surface area, allowing for a better matching of ventilation to perfusion in the pulmonary circulation.

In patients with V/Q mismatch, where some areas of the lung are well perfused but poorly ventilated, CPAP helps to redistribute airflow effectively, raising the oxygen saturation levels in the blood. This therapeutic device ultimately supports improved oxygenation in patients with compromised lung function by addressing the fundamental issues related to V/Q mismatch.