Response of regional circulations to hyperoxia.

Abstract

The effects of arterial hyperoxia on regional blood flow to the brain, bowel, and hindlimb and on total blood flow have been studied by measuring arteriovenous O2 concentration differences in anesthetized animals breathing pure O2. The use of arteriovenous O2 differences for this purpose was justified by present and by past observations that hyperoxia does not affect the O2 consumption of tissues. The present data indicate that hyperoxia decreases regional blood flow (by increasing regional vascular resistance) in varying degrees -the effect being most marked in the brain, less so in the bowel, and least obvious in the limb. As a result, the rise in venous blood O2 saturations which would be expected during O2 breathing are prevented wholly (brain, bowel) or in part (limb), and a relationship can be drawn between arterial hyperoxia and regional vaso-constriction which suggests a mechanism whereby tissue O2 tensions are stabilized.