CARBON MONOXIDE UPTAKE AND PULMONARY DIFFUSING CAPACITY IN NORMAL SUBJECTS AT REST AND DURING EXERCISE 1

Abstract

The rate of CO uptake and the fraction of CO removed from respired gas (COF) were measured in normal subjects in the steady state during rest and exercise. COF progressively declined as the minute ventilation increased with increasing exercise. The alveolar tension of CO was calculated from the Bohr relation and from expired and arterial CO tensions, and the ratio of CO uptake to alveolar CO tension was calculated as DCO DCO averaged 16.9 cc. CO/min./mm. Hg alveolar CO tension at rest and 36.3 during exercise. DCO, having reached a value approx. double the resting value during moderate exercise, showed no tendency to increase further as the severity of exercise increased. DCO was considered to be a measure of the number and size of the pulmonary capillaries available for pulmonary gas exchange and the permeability of the alveolar membrane.