Factors influencing the concentration of expired nitrogen after a breath of oxygen

Abstract

In normal subjects, the change in the concentration of nitrogen in expired alveolar air after a single breath of oxygen has been found to be affected by the presence of a pause at the end of inspiration, by varying rates of expiration, and by variations in the initial volume of air in the lungs. The effects of these different respiratory maneuvers are analyzed in terms of the over-all dilution of the inspired oxygen, of the unequal and asynchronous movements of the chest wall, and of the presence of a distribution of ventilatory time constants. The evidence suggests that there is a greater uniformity of ventilatory time constants at a middle lung volume than at a high or low lung volume. distribution of ventilation Submitted on January 27, 1964