Studies on the cerebral circulation in the aged. Dynamic analysis of the cerebral circulation by cerebral oxygen intake (CERO2)

Abstract

The CERO2, composite factor of the balance of supply and demand of oxygen in the brain, not only expresses the presence and intensity of cerebral anoxia objectively but also seems to be an important compensatory factor in the maintenance of the normal cerebral function. The circulation and metabolic function in the brain were regulated in two ways by the blood flow regulating mechanism in and outside of the brain and by the compensatory change in CERO2 of the cerebral tissue itself. The metabolic disturbance of the brain appears to be evoked by the insufficient compensation of CERO2. Taking into consideration that the results obtained by N2O method which state that the decrease in cerebral metabolism of the aged people is a secondary phenomenon of the decrease in oxygen supply to the brain, mainly the decrease in CBF, it is supposed that CERO2 in the aged people should be greater than normal young people. Usually an inverse correlation is assumed between CBF and CERO2. As the CBF of the aged is mainly due to the asteriosclerosis of the brain, a certain kind of correlation is inferred between CERO2 and cerebral arteriosclerosis. The present author, to study the correlation between CERO2 and cerebral arteriosclerosis, has measured CERO2 in healthy and anemic aged subjects, examined the clinical significance of CERO2 by comparing to the results obtained by N2O method, retinal findings, cerebral symptoms and autoptical findings, and obtained the following results. 1. The increase in CERO2 was observed in about 70% of healthy aged subjects. Such frequent cerebral anoxia in healthy older people suggests the possibility of cerebral anoxia and cerebral metabolic disturbance in the aged. 2. The assumption that the difference in CERO2 in healthy aged subjects in caused by the abnormality of cerebral hemodynamics (decrease in CBF and increase in CVR) was confirmed experimentally and by the results obtained by N2O method. 3. The fact that this increase in CVR reflects mainly the attitude of the sclerotic cerebral arteries was examined by the correlation between retinal findings, cerebral symptoms and CERO2. © 1959, THE JAPANESE CIRCULATION SOCIETY. All rights reserved.