A DIRECT METHOD FOR DETERMINATION OF OXYGEN AND CARBON DIOXIDE TENSIONS IN BLOOD

Abstract : A direct method for the determination of carbon dioxide and oxygen tensions in blood is described. The method depends upon the equilibration of a bubble of gas with blood at 37C and the analysis of the bubble for carbon dioxide and oxygen. The Roughton-Scholander syringe is used both as the equilibration chamber and bubble analyzer, thus eliminating the necessity for transfer of the bubble. At sea-level, the accuracy of the technique was tested by comparison of results with those of a tonometer technique. At simulated altitudes of 7700 to 14,200 feet (low pressure chamber), the accuracy of the technique was evaluated by comparing arterial tensions with alveolar tensions. Agreement was good in both cases. The carbon dioxide tension of shed blood containing 0.01 to 0.02 per cent sodium fluoride usually increased after 1/2 hour, probably because the blood was treated with an insufficient quantity of sodium fluoride. The oxygen tension of arterial blood dropped several mm. after 1/2 hour at room temperature, and this tendency persisted when the blood was chilled. The oxygen tension of chilled venous blood remained comparatively constant. (Author)