Diaphragmatic changes in different clinical conditions: a narrative review

Abstract

The diaphragm is the main muscle of respiration and contributes to trunk stabilization. It can be affected by diseases that damage its fibers or impair the neuromuscular bundle, leading to diaphragmatic dysfunction, with decreased inspiratory capacity and reduced endurance of the muscle itself. However, findings on its alterations are scattered across different fields and are rarely compared. Therefore, this study aimed to investigate the specificities of the diaphragm muscle in healthy individuals, postural dysfunctions, respiratory alterations, obesity, and aging. This is a descriptive narrative literature review. The databases used for the bibliographic search were SciELO, PubMed, LILACS, and the Virtual Health Library. In healthy individuals, diaphragm thickness and mobility vary according to the region measured, sex, and body type. In postural dysfunctions, the muscle shows greater fatigability and reduced excursion, affecting spinal mechanics and pain resulting from inadequate posture. In aging, there is a marked loss of muscle mass, which reduces respiratory capacity and contributes to respiratory insufficiency and decreased thoracic mobility. In chronic obstructive pulmonary disease, hyperinflation, and in obesity, the compression exerted by fat accumulation, alter the length-tension relationship of the muscle. It is concluded that the alterations differ across contexts but recur in a small number of mechanisms, and that ultrasonography may help identify the predominant mechanism and guide the choice of rehabilitation approach.