AN EXPERIMENTAL ANALYSIS IN MAN OF THE OXYGEN PRESSURE GRADIENT FROM ALVEOLAR AIR TO ARTERIAL BLOOD DURING REST AND EXERCISE AT SEA LEVEL AND AT ALTITUDE

Abstract

Measurements have been made by new technics of the pO2 gradient between alveolar air and arterial blood (A-A). The A-A gradient averaged 9 mm. Hg at rest and 16.5 mm. Hg during work. The A-A gradient is composed of 2 components: the membrane resistance and venous admixture, and a method is presented for differentiating them. At normal oxygenation the A-A gradient is composed largely of the venous admixture component, while during anoxia the membrane component constitutes most of the gradient. The increase of A-A gradient during work is one of a series of integrated cardiovascular and respiratory responses required to effect the transfer of the needed vol. of O2. The diffusion constant of the lung, calculated from the exptl. data, averaged 21 at rest and 62 during work. There were no differences in either A-A gradient or diffusion constant in the rest and work expts.