[Update on pulmonary hypertension in chronic obstructive pulmonary disease]

Secondary pulmonary hypertension (PH) is a well known possible feature in patients with chronic respiratory diseases. Owing to its frequency advanced chronic obstructive pulmonary disease (COPD) is the most common cause of PH. The studies that have focused on this topic have shown that PH is frequent during sleep, exacerbations or exercise but mean pulmonary artery pressure (PAP) is usually between 20 to 35 mmHg. Limited number of patients have severe PH, which is defined as >35 or 40 mmHg. Unfortunately, there is another subset of patients whom have minimal airway obstruction with greater PAP values called as 'out of proportion'. These two groups need special interest for further evaluation diagnosis and treatment strategy.