ISCHEMIA AND C.N. S.— PONTIUS and DE BAKEY 



267 



central iictvous system (hiring the period of teni])orarv interruption of aortic cir- 

 culation. Thus, anion^ the live cases of aneurysm of the aorta in our series, located 

 at this high level and treated liy resection without hypotliermia. spinal cord damage 

 occurred in fom" i)aticnls (fig. 5i. P'ortunately these changes were mild and tran- 

 sient in three, hut prohahly contril)Ute(l to the deatli of the fourth ])atient. 



( )n the other hand, none of the 14 cases with com])aral)le lesions similarlv treated 

 but in which hypothermia was em])loyed showed any manifestations of spinal cord 

 damage. Both in this as well as the former group the period of aortic occlusicjn 

 averaged about one hour. In the hypothermic grtnip body temperature was reduced 

 to about 85° F. (figs. 6, 7, and 8). 



Summary. 1. In a control group of 50 dogs in which the thoracic aorta was 

 occluded just distal to the left subclavian artery for a period of one hour the im- 

 mediate mortality was 32 per cent and the incidence of ischemic damage to the 

 spinal cord as manifested by paraplegia in the surviving animals was 65 per cent. 

 In a comparably treated group of 47 dogs in which hyi)othermia was used there 

 was an immediate mortality of 25 per cent, but none developed paraplegia. 



2. In a control series of 9 dogs in which the circulation to the brain was arrested 

 for a period of 30 minutes evidence of ischemic damage to the brain occurred in 6 

 (67 per cent), but none of the 9 similarly treated group in which hvi)othermia was 

 employed showed such manifestations. 



Fig. 5. — Chart of clinical cases tvithoiit hypothermia. 



