Respiratory muscles in interstitial lung disease: poorly explored and poorly understood

1. Divisão de Pneumologia, Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo (SP) Brasil. Interstitial lung diseases (ILDs) are a heterogeneous group of parenchymal lung disorders characterized by permanent structural changes that result in mechanical modifications, notably a significant reduction in the elasticity of the lung parenchyma.(1) Among individuals with ILDs, dyspnea and lower exercise tolerance are quite common complaints, varying in severity and having psychosocial repercussions, as well as a negative impact on quality of life, affecting the patients and their families. (2) Many factors, alone or in combination, can contribute to those symptoms, including altered gas exchange, airflow limitation, pulmonary vascular involvement (usually by pulmonary capillary destruction and hypoxemia-induced vasoconstriction) and left ventricular dysfunction, as well as impairment of the respiratory musculature and accessory muscles,(1-8) together with possible mechanisms specifically related to the etiology of the ILD in question.