Temporary Circulatory Occlusion to the Brain of the Hypothermic Dog

The protective effect of hypothermia against brain damage by ischemia has been well demonstrated clinically. Interruption of the circulation for up to nine minutes in open-heart surgery 1 and occlusion of the cerebral circulation for up to eight minutes in neurosurgical procedures * have been successfully accomplished. The clinical use of hypothermia presupposes that the brain takes part in the generalized reduction of tissue metabolism with cooling. That it does so was demonstrated in 1954 by Rosomoff and Holaday, 2 who found a linear fall in cerebral oxygen consumption in the dog as the temperature was lowered from 35 C to 26 C; at 26 C a threefold reduction in oxygen consumption had occurred. It is possible, therefore, that the dog at 26 C tolerates total arrest of blood flow to the brain for a period roughly three times as long as would a normothermic animal. By using graded occlusion