Electroencephalographic activity after circulatory arrest in the hypothermic dog

Abstract

Determinations were made in dogs of the time lapse between occlusion of venae cavae and electrical silence in the electroencephalograph (EEG) at several hypothermic temperatures. Moderate hypothermia appeared to have a protective effect on the electrical activity of the brain after circulatory arrest. The time lapse was found to be longest near 28 C. At lower temperatures cooling had a gradually increasing direct depressant effect on brain cell activity, and the time lapse between occlusion and EEG silence was shortened. However, near 22 C it was still longer than at normothermic temperatures. EEG activity virtually ceased at brain temperatures of 20–18 C. The results are interpreted on the basis of a depressant effect of hypothermia on the metabolic rate of the brain and a correlation between metabolic rate and EEG activity. Submitted on May 8, 1962