134 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



to 



UJ 



h- 

 Z 



100 



80 



60 



40- 



20 



Fig. 3. — Effect of carbon dioxide accumulation on oxygen consumption in closed vessels. Time 

 necessary for a rat enclosed in a vessel to diminish the partial pressure of oxygen to one-third 

 of normal; when carbon dioxide is eliminated (black portion), and when it is allowed to ac- 

 cumulate (whole bar). Each bar represents an experiment on a different animal. Capacity of 

 the vessel: 1 liter; ambient temperature: 20° C. ; weight of animals: 150-180 grams. 



fallen to dangerous values. In addition to these experimental results, other data 

 from the literature show that carljon dioxide has a specific heneficial effect on the 

 resistance to oxygen lack. There are also indications that it has a special protective 

 effect against disorders elicited hy the fall of body temperature, but this has not 

 yet been proven. 



The closed container technique uses both hypoxia and hypercapnia as agents to 

 induce hypothermia. The convenience of the technicjue consists in the fact that both 

 are produced by the animal itself and that it is only necessary to choose the right 

 size of the vessel and the ambient temperature in order to achieve the wanted level 

 of hypothermia without the danger of asphyxiation and olher harmful effects. 



The modifications of the method. Although less convenient, it is possible, as 

 already mentioned, to achieve cooling by hypoxia alone (by decreasing gradually 



