On the partial pressures of oxygen and carbon dioxide in arterial blood and alveolar air

Abstract

EVER since the work of Haldane and Priestley(l) (1905) on the pressure of C02 in alveolar air, and that of Krogh(2) (1910) on the mechanism of gas exchange in the lung, it has been generally believed that the partial pressure of C02 is the same (to a close approximation) in arterial blood and alveolar air. The relation, however, of the partial pressure of oxygen in alveolar air to that in the arterial blood has not been determined with the same accuracy. This uncertainty is due in part to the dispute concerning the role played by the lungs in oxygen transfer, in part to difference of opinion regarding the mechanics of pulmonary ventilation, and also to lack of precise knowledge of the facts. It is the purpose of this paper to present data with reference to gas exchange in the lung. Our experiments have been performed on normal men while they were breathing air or low oxygen mixtures.Method. The modification of the Haldane-Priestley method used in obtaining samples of alveolar air has been previously reported(3). For the present work we have estimated the partial pressures of both C02 and 02 in the same samples of air. In the above-mentioned communication the method used for the determination of arterial C02 pressure was described. At that time, however, equilibration of the blood was carried out at 37.50 C. In the present series of experiments all equilibrations were done at the oral temperature of the subject. Since the temperatures found under basal conditions for normal subjects are in general at least one degree below the standard temperature, the earlier determinations are about one millimetre higher than the present determinations, owing to the effect of temperature on the C02 dissociation curve. A small error in the earlier work is due to neglect of the effect of acid formation in PH. LXVIII. 18

The Effects of Hemorrhage on Pulmonary Circulation and Respiratory Gas Exchange*†

“…Normally, there is adequate perfusion of the ventilated alveoli so that an equilibrium for a readily diffusible gas, such as carbon dioxide, will exist between alveolar gas when sampled as end-tidal gas, and end-pulmonary capillary blood when sampled as arterial blood (25,27,(39)(40)(41). We found this to be true for our control determinations.…”

Alveolar and Arterial Oxygen Tensions and the Significance of the Alveolar-Arterial Oxygen Tension Difference in Normal Men 1

“…It is known that voluntary hyperventilation at sea level can raise the alveolar 02 tension without producing a proportionate rise in the arterial Po2 (34) or arterial 02 saturation (35). Dill and Penrod have reported a similar relationship occurring in subjects at simulated altitudes (36) and pointed out that the explanation for this phenomenon is not clear.…”

Analysis of the Respiratory Response to Carbon Dioxide Inhalation in Varying Clinical States of Hypercapnia, Anoxia, and Acid-Base Derangement

“…Physiological dead space ventilation was obtained using the Bohr relationship for carbon dioxide (8) assuming the arterial CO, tension to be equivalent to the mean alveolar CO, tension (9,10). Effective alveolar ventilation was taken as the difference between total pulmonary ventilation and dead space ventilation.…”