Clinical Studies on the Respiration

Failure to obtain the required amount of oxygen or to remove a sufficient quantity of carbon dioxid from the body tissues results in the subjective sensation of dyspnea. The maintenance of a gaseous exchange which is adequate for the needs of the metabolism depends on the coordination of several factors, and insufficiency of any one of these may produce dyspnea, but we proposed here to consider only the subject of the pulmonary ventilation. With the body at complete rest the demand for oxygen is supplied and the excess carbon dioxid is removed when an individual is breathing from 4 to 5 liters of air per minute. Physical exertion requires a greater gaseous exchange and this is met by an increase in the amount of air breathed which is nearly proportional to the rise in metabolism. The degree, therefore, to which the metabolism may be increased by physical exertion without the