THE EFFECT OF THE INHALATION OF GASES WITH A LOW OXYGEN AND AN INCREASED CARBON DIOXIDE-TENSION ON THE PERIPHERAL BLOOD FLOW IN MAN

Abstract

Expts. were carried out on ten trained normal subjects in which the influence of the inhalation of various gas mixtures on the blood flow in the human hand was studied. It was found that CO2 in air (4-5.4%) regularly reduces the blood flow. On readmission of air the blood flow rises to the original control level. A compensatory phase is conspicuously absent. Inhalation of gas mixtures containing 7.6-9.8% O gave variable results. In the milder degree of O lack (9.8%) the response to O lack was pre-dominantly an increased blood flow, whereas with lower O cones, the blood flow was either decreased, unchanged or slightly increased. On readmission of air a compensatory blood flow was observed in most cases. The variability of the results is due to the fact that the central sympathetic impulses compete with the dilatory effect of local metabolites. The regularity of the results obtained with CO2 makes these expts. a more suitable test for the presence or absence of sympathetic impulses rather than expts. involving O want.