Blood and Tissue Gases of Animals Exposed to One and Seven Atmospheres of Oxygen or Air

Abstract

O2 poisoning has been studied by analyses of gas from an abdominal bubble and arterial blood in rabbits and rats. During exposure to 1 atm. of O2 there was no significant change in tissue O2 and CO2 tension as reflected in the abdominal bubble until there was evidence of pulmonary damage and change in arterial gas contents. The cause of death at 1 atm. O2 seems to be asphyxia resulting from pulmonary damage. Abdominal and arterial and venous blood gases were also studied in rats under 7 atm. O2 and under control conditions with 7 atm. total pressure but 1 atm. O2. In the former an abdominal pCO2 of about 65 mm. Hg rapidly appeared in such animals and was maintained for 12-15 min. This pCO2 is 15-20 mm. Hg higher than that obtained at ambient pressure and may reflect saturation of venous blood with O2 and embarrassment of CO2 transport by hemoglobin. After 12-15 min. the abdominal PCO2 rose rapidly and probably represented general failure of the organism. Evidence is given that exchange of CO2 between tissues and abdominal bubble is rapid and that samples taken after rapid decompression contain significantly more CO2 than samples taken under pressure. A change in CO2 combining power of the blood has been demonstrated and the suggestion is made that this reflects accumulation of fixed acid.