Mechanical ventilation is a respiratory support therapy that can cause diaphragm muscle injury and induce dysfunction, which is associated with prolonged ventilation, weaning failure and mortality. Protecting the diaphragm during ventilation requires the use of tools to monitor diaphragmatic effort. The aim of this review was to address current and relevant elements about the pathophysiology of diaphragmatic function in ventilated patients. For this purpose, a narrative review of the literature available in Google Scholar, Pumed/Medline, regional SciELO, and academic Google was carried out under the terms: diaphragmatic function-diaphragmatic function in ventilated patients/diaphragmatic ultrasound in ventilated patients pathophysiology/ diaphragmatic function and others. Fundamental theoretical contents on the clinic of diaphragmatic muscle dysfunction, its relationship with artificial ventilation and related structures, such as the lung, are addressed. It is concluded that the diaphragm represents the main muscle involved in respiration and diaphragmatic muscle dysfunction represents a frequent complication in critically ill patients. Diaphragmatic ultrasound is a tool that aids decision making on artificial ventilation, potentially reduces the duration of respiratory support and associated complications