Les explorations fonctionnelles respiratoires de repos et à l'exercice dans l'HTAP

Pulmonary arterial hypertension (PAH) is a rare and complex disease, which requires careful diagnostic evaluation. In most of studies, pulmonary function tests of patients with PAH objective a mild restrictive defect in lung volume measurements but a distal airway obstruction may be also identified, with expiratory airflow limitation and premature airway closure leading to a moderate hyperinflation. Mild to moderate arterial hypoxemia, often associated with a mild respiratory alkalosis, and diffusing capacity for carbon monoxide decrease are also described. In patients with idiopathic pulmonary arterial hypertension, hypocapnia (carbon dioxide arterial tension <4.25 kPa) and DLCO decrease are independent markers of mortality. The exhaled fraction of nitric oxide NO (FENO) determined at multiple expiratory flows and membrane diffusion and capillary blood measurements are promising tests but actually there's no recommandation for using these tests in routine. There is an increasing recognition of the potential value of cardiopulmonary exercise testing (CPET) in patients with PAH. Current evidence indicates that CPET provides an accurate depiction of PAH disease severity and may provide information on the response to therapeutic interventions and prognosis. But research using CPET in PH should continue to better determine the clinical utility of this exercise assessment.