[Blood acid-base equilibrium during breathing of hypercapnic gas mixtures]

By the method of Astrup-Zigaard-Andersen the acid-base balance in the blood of men and dogs exposed to hypercapnic atmospheres with a normal, increased and decreased oxygen content was investigated in 164 experiments. Variations in the acid-base equilibrium were compared with changes of physiological functions. The relationship between the acid-base balance and the carbon dioxide concentration as well as the oxygen concentration in the breathing air was established. The toxic effects of sharp hypercapnia and hyperoxia were shown to cumulate. The positive effect of moderate hypercapnia on the tolerance to normobaric hypoxia in long-term experiments was noted.