Effects of prolonged oxygen therapy on pulmonary hypertension and blood viscosity in patients with advanced cor pulmonale.

In 16 patients with chronic bronchitis and advanced cor pulmonale admitted to hospital due to heart failure, a controlled 6-weeks oxygen therapy, 17 h a day, was performed. The trial was started when patients were out of the exacerbation of the disease in a respiratory and circulatory steady state. Pulmonary hemodynamics, blood viscosity, packed cell volume and basic lung function data before and after oxygen therapy were compared. A significant fall of mean pulmonary arterial pressure from 42 to 30 mm Hg without a change in the cardiac output was found. Blood viscosity and packed cell volume-significantly decreased. Arterial oxygen tension did not significantly change. It seems that 17-hours per day oxygen therapy is sufficient to induce regression of anatomic changes in pulmonary arteries, a main cause of pulmonary hypertension in hypoxic cor pulmonale.