Respiratory and circulatory adaptation to isometric and dynamic exercise in chronic lung disease.

Changes at the beginning of isometric and dynamic low level exercise were studied in 23 patients with chronic lung disease. Ventilation, oxygen consumption and vascular pressures in systemic and pulmonary circulation were continuously monitored, and cardiac output was measured by thermodilution every minute. Circulatory changes took place suddenly at the beginning of isometric exercise and gradually during dynamic exercise. Ventilatory changes followed almost the same progressive pattern in both types of exercise. Ventilation increase in relation to oxygen uptake was slightly smaller during isometric exercise. Pulmonary artery pressure showed no further increase after the initial change, although ventilation was still rising.