Pulmonary arterial hypertension (PAH) is a severe and progressive disease with limited survival prospects under currently available therapies. It is a rare condition, with a prevalence of 47.6–54.7 cases per million and an average annual incidence of 5.8 cases per million worldwide. Despite improvement of prognosis after the introduction of specific PAH therapies including the use of early treatment in double or triple combination regimens, the prognosis for PAH patients still remains poor. Mortality is determined by several factors, in particular by the presence of right ventricular dysfunction and/or hemodynamic instability; especially when episodes of respiratory failure, which are difficult to treat, lead the patient to hospitalization.