HYPOTHERMIA AND THE CENTRAL NERVOUS SYSTEM 



H. L. ROSOMOFF 



You are probably famiHar witb tbe work of Dr. D. A. Holaday's and mine, 

 published about a year ago, in which it was demonstrated that both cerebral blood 

 flow and oxygen consumption decrease at the same rate during hypothermia in 

 this temperature range. I present this as evidence to refute the statement of Dr. 

 D'Amato in which he proposed that the peripheral circulation was a direct reflection 

 of the cardiac output. The data in figure 1 would suggest that this is not true ; it 

 suggests that there is a mechanism of circulatory control within the brain. 



This becomes more certain when the data in figure 2 are considered. The average 

 cerebral blood flow falls at a rate of 6.7 per cent per degree Centigrade. The mean 

 blood pressure decreases at a somewhat slower rate, 4.8 per cent per degree Centi- 

 grade. Therefore, cerebral vascular resistance must increase, and it does two- to 

 three-fold. 



The cerebral blood flow preparation is a method by which the blood flow is ob- 

 served continuously so that one is able to follow constantly the dynamics of the 

 cerebral circulation. It was interesting to note that for each temperature decrement 



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TEMPERATURE 



Fig. 1. — Decrease of cerebral blood flow and oxygen consumption with lowered temperature. 



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