252 PHYSIOLOGY OF INDUCED HYPOTHERMIA 



1.6 O 



1,4 O 



o X 



1,2 o o X • 



cr 



X 

 1,0 o o 



X • 



,8 • 



o 



• 6 • • 



.4 •= 5 % COe 



x= 2 % CO2 



0= HYPERVENTILATION 



10 20 30 40 50 60 70 80 90 100 



ApCOz 



Fig. 2. — Efifect of ApCOo on the cerebral metabolic rate in hypothermia. 



In figure 2 the ApC02 is plotted on the abscissa and the cerebral metabolic rate 

 (cerebral oxygen consumption) is plotted on the ordinate. It is clear that the ani- 

 mals with the highest ApCOg appear to have the lowest cerebral oxygen consump- 

 tion. The reason for this is not entirely clear, but it may be that at the lowered 

 levels of metabolic activity in hypothermia this concentration of COo acts as an 

 accessory anesthetic agent. 



REFERENCES 



1. Rosomoff, H. L., and Holaday, D. A. : Cerebral blood flow and cerebral oxygen consumption 



during hypothermia, Am. J. Physiol. 179: 85-88, 1954. 



2. Kleinerman, J., and Hopkins, A. L. : Efifects of hypothermia on cerebral blood flow and 



metabolism in dogs, Fed. Proc. 14: 410, 1955. 



