Hypoxia and its influences on the cardiovascular and respiratory systems of spontaneously breathing cats

ABSTRACT

Effects of acute systemic hypoxia on the cardiovascular system [CVS] and respiration of spontaneously breathing cats were studied in two conditions. 1] Hypoxic air [6-8% 02 in N2] was given to the animal to induce systemic hypoxia for 20 minutes. Hyperventilation at this condition lowered arterial C02 tension [PaC02; hypocapnia]. 2] In the second run, induction of hypocapnia was prevented by adding 3-5% C02 to hypoxic air. Comparison of the results of this study indicated that hypoxia, independent of the presence of hypocapnia, caused a significant increase in respiratory rate, aortic flow and arterial blood pressure. However, in the presence of hypocapnia, the increased respiratory rate was 10% less and a general arterial vasconstriction was observed