Improved haemodynamics but reduced arterial blood oxygenation, at rest and during exercise after long-term oral prazosin therapy in chronic cor pulmonale

The effect of vasodilator therapy in chronic obstructive lung disease with pulmonary hypertension was evaluated in eight patients during oral prazosin therapy (2–10 mg day −l). After one week, prazosin reduced mean pulmonary artery pressure and pulmonary and systemic vascular resistance, and increased cardiac index both at rest and during exercise. Similarly improved haemodynamics were observed after two months of therapy. Arterial PO2 and oxygen saturation fell significantly after two months both at rest and during exercise, but were not changed after one week. Lung function tests were not altered by prazosin. Thus, although prazosin improves the haemodynamics in patients with chronic obstructive lung disease, caution is advised in long-term therapy since prozosin worsens the arterial blood oxygenation.