Observations on Selective Brain Cooling in Dogs

Hypothermia has proved to be a doubleedge sword, for while protecting the brain against anoxia it threatens the heart with arrhythmia. This undesirable effect has led to attempts to cool the brain profoundly, while lowering the heart temperature only moderately. Several groups1,12,14,17have accomplished this by shunting carotid blood through a heat exchanger. Woodhall and collaborators27used a circuit whereby jugular blood is oxygenated and cooled and then recirculated through the brain. We were encouraged by the report of Kimoto et al.,12who cited successful use of an extracorporeal carotid cooling system as an adjunct to open heart surgery in 9 of 11 human cases. The present study was undertaken to gain experience with the new technique of blood-stream cooling, and to enlarge on observations reported by others. We sought specifically to compare surface cerebral temperatures with those in the depths of the cerebrum and cerebellum, and