Treatment of pulmonary hypertension in chronic obstructive pulmonary disease

Abstract

In chronic lung disease and especially in chronic obstructive pulmonary diseases (COPD), pulmonary hypertension (PH) is generally mild to moderate. The necessity for treating a mild PH (pulmonary artery mean pressure (Ppa) of 20-35 mmHg in most patients) can be questioned. But PH, even when modest, may worsen markedly during acute exacerbations of the disease, during exercise and even during sleep. These acute increases in Ppa could contribute to the development of right heart failure. The prevention of right heat failure, which is observed unequivocally in some COPD patients is indeed a valuable outcome of treatment of PH. There are presently no selective pulmonary vasodilators, with the exception of inhaled nitric oxide (NO) but NO has not been used in long-term studies. Similarly, epoprostenol (prostaglandin I2), a powerful, nonselective vasodilator has been used with good results in 'primary' PH, but this treatment, which supposes a severe degree of PH has not yet been given to COPD patients. Considering that the long-term effects of calcium channel blockers and other vasodilators have been rather disappointing and that the side-effects are frequent, there is at the present time no justification for the long-term use of vasodilators in COPD. Since chronic alveolar hypoxia plays a major role in the development of PH in COPD, the logical treatment of hypoxic PH is the prolonged administration of O2, with the hope that the structural changes of the pulmonary circulation are at least partially reversible. Recent studies including the Nocturnal Oxygen Therapy Trial and our own investigation have shown that the haemodynamic results of long-term oxygen therapy (LTOT) are modest, but rather favourable. LTOT delays the progression of PH with a stabilization or an improvement of Ppa in most patients. LTOT must be given during ≤18·day-1. In fact some patients 'respond' better than others to LTOT, but we are not able to discriminate them at least at the onset.