RESPIRATORY RESPONSE DURING EXERCISE IN PULMONARY FIBROSIS AND EMPHYSEMA

Abstract

The minute volume, respiratory rate and tidal volume were measured in 20 normal subjects and 28 patients with chronic cardiac and pulmonary diseases at rest and during moderate and exhaustive effort on a stationary bicycle ergometer. Blood was obtained from the radial artery immediately before and after moderately severe exercise in 9 cases of pulmonary fibrosis and emphysema. The patients, in contrast to normal individuals, had a greater minute ventilation and a more rapid and shallow type of breathing at rest and during moderate exertion. The degree of dyspnea was proportional to the expression total ventilation/vital capacity. Dyspnea was experienced when the value for this ratio was greater than 51 and when this value was exceeded at low levels of work it was an indication of pathological dyspnea. The pulmonary reserve was a measure of the tendency to dyspnea. Normal individuals could increase their resting ventilation 9 fold, while in patients who were disabled by fibrosis and emphysema, the pulmonary reserve was so reduced that on moderate exertion the ventilation constituted more than 60% of the maximum ventilatory capacity. As the values for the expression total ventilation/vital capacity increased and the pulmonary reserve decreased, the vital capacity and the oxygen saturation of the arterial blood decreased and the ability to expand the chest diminished. After exercise the oxygen content and the oxygen saturation of the arterial blood increased in the majority of the patients with pulmonary fibrosis.