Alveolar-Arterial O2 and CO2 Differences in the Dog Breathing Air and Low O2 Mixtures

Abstract

The alveolar-arterial pressure difference for O2 and CO2 were recorded in the dog breathing air and 12-15% 02- The alveolar gases were recorded continuously from an end-tidal sampler while arterial blood samples were drawn for analyses. A comparison of the CO2 values showed no statistical difference. The 02 differences varied from 24 mm. in the awake or lightly anesthetized dog breathing air to 5-6 mm. when the inspired 02 tension was lowered. The O2 differences of breathing air are attributed largely to unequal ventilation/perfusion ratios existing in the lung.