Which pressure is maintained in the lungs during exhalation?

During exhalation, the pressure that is particularly relevant is the positive end-expiratory pressure. This refers to the pressure that remains in the lungs at the end of expiration, which is essential for keeping the alveoli open and ensuring effective gas exchange. Positive end-expiratory pressure helps prevent the collapse of the airways and alveoli, allowing the lungs to maintain a certain volume of air even after exhalation has occurred.

In this context, while intrapleural pressure varies throughout the respiratory cycle, it is the positive end-expiratory pressure that specifically indicates the pressure levels that are maintained within the lungs at the end of expiration. This is crucial in clinical settings, especially in mechanically ventilated patients, to avoid atelectasis (lung collapse) and to facilitate adequate oxygenation. The other pressures mentioned, such as intrapleural pressure and transpulmonary pressure, while important, do not specifically denote the maintained pressure during the phase of exhalation as does the positive end-expiratory pressure.