Monitoring cerebral blood flow and oxygen, glucose, lactate and ammonia metabolism.

Abstract

New application of methods for monitoring cerebral blood flow and cerebral arteriovenous oxygen, glucose, lactate and ammonia differences are described. Results of trials of their validity in monkeys during experimental procedures are described. The apparatus includes infrared gas analyzers for monitoring arteriovenous differences after diffusion of nitrous oxide through silastic, electromagnetic flowmeters for monitoring cerebral venous outflow, the Technicon apparatus for measuring arteriovenous differences for lactate, glucose and ammonia, and the Guyton analyzer for monitoring cerebral arteriovenous oxygen differences. Cerebral blood flow in the monkey measured by the nitrous oxide method was 61 ml/100 g brain per min, cerebral oxygen consumption was 2.8 to 3.35 ml/100 g brain per min, cerebral glucose consumption was 3.52 mg/100 g brain per min, cerebral arteriovenous lactate difference was 1.1 mg/100 ml, cerebral arteriovenous ammonia difference was 2 mg/100 ml. Inhalation of 100% oxygen, 5% CO 2 in air, 20% CO 2 in air and hyperventilation caused no change in cerebral oxygen, glucose, lactate, and ammonia metabolism. During anoxic anoxia, cerebral glucose consumption increased and cerebral oxygen consumption decreased significantly. During seizures, cerebral metabolic rate for oxygen increased. No important changes in ammonia metabolism were noted. It was concluded that it is feasible to apply these methods concurrently in patients with cerebrovascular disease before and after therapeutic trials.