Cerebral blood flow, cerebrovascular resistance and cerebral metabolic rate of oxygen in severe arterial hypoxia in dogs.

Cerebral blood flow and cerebral oxygen uptake were studied during severe arterial hypoxia in anesthetized dogs. It was shown that the hypoxic vasodilatation in the brain reaches a limit at an arterial oxygen saturation at about 25% and that this vasodilatation is less than that which may be induced by hypercapnia. A further deepening of the arterial hypoxia at a maintained cerebral perfusion pressure is combined with a continuous decrease in cerebral venous oxygen tension and a reduced oxygen uptake.