Pulmonary hypertension associated with chronic lung diseases.

In 2015, the international guidelines for diagnosis and treatment of pulmonary hypertension (PH) were updated. Group 3 of the current classification includes PH associated with chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD), other pulmonary diseases with restrictive and obstructive pattern, sleep-disordered breathing, alveolar hypoventilation disorders, chronic exposure to high altitude, and developmental lung diseases [1]. PH associated with COPD and ILD is common but difficult to manage, as no long-term randomised controlled trial (RCT) has been conducted with specific pulmonary arterial hypertension (PAH) drugs in PH associated with COPD, and the one recent RCT in PH associated with ILD had to be stopped early due to a possible increased risk of death and side effects in the treatment group. Specific treatment may thus be harmful and may worsen gas exchange as a result of possible recruitment of less oxygenised areas, i.e. by increasing ventilation-perfusion mismatch. Management of PH patients with chronic lung diseases requires careful evaluation and understanding of pathophysiological mechanisms. Interestingly, mediators in PAH and in fibrotic lung disease show some overlaps. Several drugs effective in PAH have been evaluated for anti-fibrotic treatment in ILD, but until today without consistent success. While new drugs with anti-fibrotic effects are now accessible, a specific evidence-based treatment for PH in ILD or COPD with or without emphysema is not yet available.