THE BLOOD FLOW IN THE BRAIN AND THE LEG OF MAN, AND THE CHANGES INDUCED BY ALTERATION OF BLOOD GASES 1

Abstract

The solution of various neurological problems awaits an increase in our knowledge of the circulation of blood within the brain. Much has been gained by the demonstration of Forbes (1) and his co-workers that the pial vessels of the cat are under both vasomotor and chemical control. These experiments consisted of actual inspection and measurement of pial vessels viewed through a window screwed in the skull, the pressure of the cerebrospinal fluid and of the blood being measured simultaneously. In particular, Wolff and Lennox (2) showed that changes in the gaseous content of the blood had a prompt and clear cut effect on the diameter of pial vessels, an effect which was independent of the systemic blood pressure. These authors observed that an increase in the carbon dioxide content of the blood was attended by an extreme dilatation of pial vessels whereas a decrease was followed by a constriction. Variations in oxygen content resulted in relatively small changes. An increase in oxygen tension produced a slight constriction and a decrease in tension a slight dilatation of the observed vessels.