No correlation between cerebral blood flow and neurologic recovery after reversible total cerebral ischemia in the dog

Abstract This study was conducted to determine if regional cerebral flow during the first day after total cerebral ischemia was correlated with neurologic deficit and eventual survival. Dogs were subjected to 11 min of total cerebral ischemia (TCI) produced by an arterial and venous double balloon occlusion method. Recovery was allowed for up to 7 days after reperfusion, whereupon it was reassessed in survivors. Blood flow, determined by the radiolabeled microsphere method, was determined before TCI and at times up to 24 h after reperfusion. Blood flow during reperfusion after TCI followed the expected pattern of immediate hyperperfusion followed by prolonged hypoperfusion. TCI of 11 min duration resulted in a 50% mortality rate by 1 week. No positive correlation between magnitude or duration of hypoperfusion and neurologic deficit or mortality was found. It was concluded that improved postischemic blood flow cannot be used as a criterion for assessing drug therapy without reference to metabolic demand. The observation of a statistical correlation between dogs that survived and lower hematocrit was reported. It was suggested that the prolonged hypoperfusion encountered after TCI was not pathological, but rather served as a mechanism to limit oxygen exposure to the brain during a vulnerable period and, thus, was part of a controlled attempt at recovery of function by the central nervous system.