Define continuous positive airway pressure (CPAP).

Continuous positive airway pressure (CPAP) is defined as a mode that maintains a constant airway pressure during spontaneous breathing. This method is designed to keep the airways open and ensure adequate oxygenation and ventilation by delivering a continuous flow of air at a set pressure level throughout the breathing cycle.

This mode is particularly beneficial in treating conditions such as obstructive sleep apnea, where it helps prevent airway collapse during inhalation. By providing this constant pressure, CPAP improves lung function and reduces the work of breathing, allowing for more effective gas exchange.

The other options do not accurately describe CPAP's purpose or functionality. For instance, a mode that provides no pressure assistance would not achieve the therapeutic goals associated with maintaining airway patency. Similarly, a form of ventilatory support that delivers only oxygen does not address airway pressure management, which is fundamental in CPAP. Lastly, suggesting that CPAP is used exclusively for intubated patients is misleading, as CPAP is often utilized in non-invasive settings and for patients who are spontaneously breathing.