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PHYSIOLOGY OF INDUCED HYPOTHERMIA 

 DOG N0.39I 22 SEPT. 55 



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Fig. 13.- — Skin and deep colonic temperatures on cooling in a representative experiment. 



hypothermic range of 30 to 32° C. One dog displayed such irritability at a core 

 temperature of 34° C. induced by minimal change in the position of the colonic 

 thermocouple, consistently causing an abrupt systolic blood pressure elevation of 

 50 to 60 mm. Hg. and a diastolic elevation of about 40 mm. Hg. 



Four dogs died while routine cooling curves were being run. Their deaths were 

 characterized by sudden collapse. Artificial respiration and massage of the chest 

 were of no avail. One dog with a colonic temperature of 29° C. died after a bout of 

 exercise, jumping rapidly from the cage to the floor of the room, whereas, in a pre- 

 vious cooling run it had survived a core temperature of 27° C. Shivering was pres- 

 ent in the other 3 dogs at the time of their death, all of which occurred when the 

 core temperature was 28° C. It seems reasonably certain that ventricular fibrillation 

 was the cause of death in these animals. 



Mental awareness, movements of progression and related functions. Cen- 

 tral nervous and neuromuscular functions are not seriously disturbed by body tem- 

 peratures as low as 28° C. This is reflected by the fact that the animal remains fully 

 oriented with its surroundings ; it may jump eargerly from the cage to the floor, 

 smell out food, jog to food thrown across the room, chew and swallow without any 

 obvious disturbance in deglutition or digestion, refuse feces as food and respond 



