Hypertension pulmonaire des affections respiratoires chroniques

Pulmonary hypertension caused by chronic respiratory disease is defined as an increase in mean resting pulmonary artery pressure to more than 25 mm Hg. It is the commonest form of precapillary pulmonary hypertension owing to the high prevalence of chronic obstructive pulmonary disease. It is caused primarily by alveolar hypoxia which induces distal pulmonary vasculature remodelling and, by extension, an increase in pulmonary vascular resistance. It is not as serious as idiopathic pulmonary arterial hypertension. Mean pulmonary artery pressure is usually moderately elevated when patients are seen during a stable phase of the disease, but may rise steeply during exercise or periods of respiratory decompensation. However, severe forms of pulmonary hypertension also exist which, in certain cases, are referred to as “disproportionate”. Pulmonary hypertension caused by respiratory disease results in elevated right ventricle afterload potentially leading to right ventricle failure which is a poor prognostic factor. The clinical symptoms of pulmonary hypertension are generally secondary to those of the underlying disorder and the condition can be diagnosed non-invasively using Doppler echocardiography. At the present time, treatment is the same as for respiratory failure, consisting of long term oxygen therapy (for more than 16-18 hrs/24 hrs) and/or long term mechanical ventilation.