STUDIES OF THE PULMONARY CIRCULATION AT REST AND DURING EXERCISE IN NORMAL INDIVIDUALS AND IN PATIENTS WITH CHRONIC PULMONARY DISEASE

Abstract

Studies of cardiac output and pulmonary arterial pressure were performed using the venous catheter technic in 3 normal individuals and in 8 patients with various types of chronic pulmonary disease. Measurements were made at rest and during exercise on a stationary bicycle. Two of the 3 normal subjects showed a decrease in the mean pressure in the pulmonary artery during exercise; all showed a marked drop in pulmonary vascular resistance and a minimal increase in the work of the right ventricle during exercise. Three of the patients with chronic pulmonary disease showed a significant elevation of pulmonary arterial pressure at rest and, in all 8 cases, the mean pressure increased during exercise. There was either no change or an increase in the pulmonary vascular resistance during exercise, and the work of the right ventricle was invariably higher than in the normal subjects at a corresponding work level. The findings indicate that the expansibility of the pulmonary vascular bed during exercise is limited in patients with chronic pulmonary disease. Anoxia may contribute to the elevation of pulmonary arterial pressure during exercise in those patients whose arterial O2 saturation falls.