[Pulmonary hypertension in chronic respiratory diseases]

Pulmonary hypertension is frequent in advanced chronic respiratory diseases, with an estimated prevalence at the time of pulmonary transplantation of 30-50 % in idiopathic pulmonary fibrosis, 30-50 % in chronic obstructive pulmonary disease, 50 % in combined pulmonary fibrosis and emphysema, 75 % in sarcoidosis, and more than 75 % of cases in pulmonary Langerhans cell histiocytosis. Histologic features include varying degrees of pulmonary arterial remodeling (prominent), vascular rarefaction (emphysema), fibrosis or specific involvement of the pulmonary arteries (idiopathic pulmonary fibrosis, sarcoidosis, lymphangioleiomyomatosis, pulmonary Langerhans cell histiocytosis), in situ thrombosis, and frequently associated involvement of the pulmonary veins (idiopathic pulmonary fibrosis, sarcoidosis). Pulmonary hypertension is usually detected using echocardiography with Doppler, however right heart catheterisation is required to confirm precapillary pulmonary hypertension defined by pulmonary artery pressure ≥ 25 mm Hg, with pulmonary artery wedge pressure ≤ 15 mm Hg. When present, it is associated with decreased exercise capacity and worse mortality. Pulmonary hypertension in chronic respiratory disease is almost invariably multifactorial; hypoxia is one of its main determinants, however supplemental oxygen therapy rarely reverses pulmonary hypertension. Management of pulmonary hypertension in chronic respiratory disease is mostly based on the optimal treatment of the underlying disease. Available data do not support the use of drug therapies specific for pulmonary hypertension in the setting of chronic respiratory diseases, however very few clinical studies have been conducted so far specifically in this context.