The expiratory muscles are the “neglected component” of the respiratory muscle pump. Rather as the heart does not comprise only a left ventricle, but also a right one, the respiratory muscle pump is much more than just the diaphragm.

In this paper, we have summarized the physiology and pathophysiology of expiratory muscles, with a special focus on critically ill patients.

Expiratory muscles are frequently recruited in critically ill ventilated patients, but a fundamental understanding of expiratory muscle function is still lacking in these patients.

Gastric pressure monitoring provides multiple bedside parameters for analysis of expiratory muscle effort, but their clinical implications need to be established.

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