[Pulmonary artery hypertension in chronic respiratory diseases]

Pulmonary hypertension (PH) is one of the evolutive complications in respiratory diseases leading to chronic respiratory insufficiency (CRI). In most cases PH is mild, but acute worsening can happen and especially during exercise, during sleep (particularly during rapid-eye-movement sleep) and during acute respiratory failure. Usually, pulmonary artery pressure finds again the level observed prior to the worsening. Although PH is usually mild, it is of prognostic value in CRI and particularly in patients with chronic obstructive pulmonary disease (CODP): the survival rate is significantly lower in patients with PH compared with those without PH and the higher PAP is the lower the survival rate. In general, long-term changes in PAP in COPD patients are mild. Long-term oxygen therapy can reverse the progression of PH and increase the survival rate. PH can lead with more or less delay to cor pulmonale and right heart failure (RHF). Oedema can be due to RHF but in some cases they can also be explained by the stimulation of the renin-angiotensin system with increasing of the aldosterone level, due to the fall in renal blood flow. These renal hemodynamic changes are related to arterial blood gas changes (hypercapnic acidosis, hypoxemia).