364 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



B-R |Cbj^ 

 SPIROMETER 



Fig. 1. — Patient in ice-water bath, prepared for operation. 



brain and prevention of further cerebral damage from anoxia secondary to spasm 

 of the affected artery. A "slack" brain accompanies hypothermia in a substantial 

 proportion of cases. In a smaller proportion the blood pressure is reduced (fig. 3). 

 Exposure of the aneurysm is therefore made easier with a lessened likelihood of 

 recurrent rupture. Should the aneurysm bleed during exposure, uncontrollable 

 hemorrhage and clipping of the main artery are avoidable, for one may temporarily 

 interrupt the cerebral circulation completely or in part. This is done in safety by 

 occlusion of the carotid or carotid and vertebral arteries in the neck, or the 

 appropriate intracranial artery. 



Case report. The case of B.H. demonstrates the advantage of hypothermia. 

 This 45-year-ol(l woman, between 1 July 1955 and 1 August 1955, had four sub- 

 arachnoid hemorrhages. The third and fourth attacks were followed by uncon- 

 sciousness and confusion, which cleared. She was referred on 29 September to the 

 Toronto General Hospital for further treatment. 



Examination on admission revealed the patient to be fully conscious without 

 localizing symptoms save for slight ptosis on the left side. 



Arteriograms demonstrated a left supraclinoid aneiu-ysm (fig. 4). 



Operation was carried (jut on 5 October 1955 under hypotliermia. At 29.2° C. 



