Pulmonary gas exchange in chronic obstructive lung disease patients with pulmonary hypertension

To ascertain if any specific changes are associated with the development of pulmonary hypertension in patients with chronic obstructive lung disease, respiratory gas exchange was measured at rest and during exercise in 52 such patients, of whom 22 already had pulmonary hypertension at rest and/or during exercise. Lung function, gas exchange and haemodynamic indices in the hypertonic group were compared with those in the normotonic group. It was shown that gas exchange was not altered by pulmonary hypertension in any specific fashion. The differences found were related to the higher age of the patients and the higher degree of obstruction present in them, leading in turn to a higher degree of ventilation-perfusion mismatch responsible for the lowered PaO2 ane elevated PaCO2.