Value of Carbon Dioxide in Counteracting Oxygen Lack

Abstract

THE recent paper by Childs, Hamlin and Henderson¹ has again centred attention upon the old observations of Mosso², who showed that in low-pressure chamber experiments the presence of small concentrations of carbon dioxide (2–5 per cent) increased the resistance of his experimental subjects to lowering of the barometric pressure. Similar observations were reported by Margaria³, and Talenti⁴, who found that the resistance against the lowering of the barometric pressure was increased in the presence of carbon dioxide, provided that the gas mixture in the chamber was pure oxygen. The attempts, however, to prove that carbon dioxide had a similar beneficial effect on oxygen lack when air was diluted by nitrogen gave paradoxically negative results (Margaria⁵). In view of the contradictory character of these earlier studies, and since it has been shown that oxygen lack produces quantitatively measurable effects on the human central nervous system (Gellhorn and Spiesman⁶, and Gellhorn and Kraines⁷), it seemed to be of considerable interest to investigate whether the effects of oxygen lack on the human central nervous system could be alleviated or altered by the presence of carbon dioxide and, furthermore, to ascertain what the mechanism of this reaction might be.