The cause of cardiac dyspnea and air hunger is still disputed. The fact that it cannot be explained simply by alteration of the carbon dioxide and oxygen content of the blood1 opens the way for renewed investigation of other respiratory factors.
Greene and Coggeshall2 showed that increases in the expiratory position of the chest take place in normal subjects during muscular work and while basal metabolism is being measured. Two of their subjects who manifested such an increase also experienced shortness of breath, but when one of us (J. A. G.)3 exposed normal subjects to high concentrations of carbon dioxide and low concentrations of oxygen, both simultaneously and separately, a constant increase in the expiratory position of the chest did not occur. In these experiments precautions were taken to reduce psychic factors to a minimum.2
The purpose of the present investigation was to study the effect
GREENE JA, HEEREN RH. CLINICAL STUDIES OF RESPIRATIONRELATION OF DYSPNEA AND AIR HUNGER TO CHANGES OF THE EXPIRATORY VOLUME OF THE CHEST. Arch Intern Med (Chic). 1936;57(1):100–105. doi:10.1001/archinte.1936.00170050108009