CLINICAL STUDIES ON THE RESPIRATION

Abstract

In a former paper¹observations were reported on the effect of increasing the carbon dioxid content of the inspired air in normal persons and in patients with cardiac disease. It was shown that in normal persons the minute-volume of air breathed doubled when the concentration of carbon dioxid was between 4.2 and 5.4 per cent., and that cardiac patients, excepting those with a demonstrable acidosis, behaved in an approximately similar manner. In order to obtain further information as to the mechanism of dyspnea in heart disease additional observations have been made in which the subjects have been allowed to continue breathing until the carbon dioxid in the inspired air produced a high degree of dyspnea. It was hoped that at the height of dyspnea more difference would be found between the mechanism of the respiration in the normals and in the cardiac patients than was obvious when lower concentrations of