278 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



M-24-H 19 MINUTES OOCLUSIOW TEMP WC PWEOCCUUSIOW 



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M-24-S5 19 MINUTES OCCLUSION TCMR 2«*C PREOGCLUSION 



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lM-24-59 iSMINUTES OCCLUSION TIMRJ«^ 



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M-24-M 15 MINUTES OCCLUSION TEMP M-c POSTOCCLUStON 



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Fig. 1. — Photograph of a series of electroencephalographic tracings obtained in a monkey 

 subjected to IS minutes of cerebral afferent occkision at temperature 24° C. The tracings read 

 from left to right. The first tracing is a control at 33° C. ; the second is at 24° C. before occlu- 

 sion; the third is at 24° C. during occlusion (note the marked depression of electrical activity) ; 

 the fourth is at 24° C. after release of occluding clamps ; and the fifth is at 35° C. after 

 rewarming. (Dr. James D. McMurrey) 



strated a markedly diminished oxygen utilization, in the range of 31 to 27° C. 

 without much change helow that temperature range. We felt that it \\as unneces- 

 sary to take our animals helow 27° C. in order to achieve a near minimal utilization 

 of oxygen. 



In some of oiu" monkeys we ol)served that the electroencei)hal(igrai)hic tracing 

 did not completely disappear. Sometimes we were al)k' to ]^roduce complete dis- 

 appearance hy readjustment of the clami)s. and in one or two of our monkeys we 

 discovered that there was an afferent vessel not occluded at the time of the original 

 application of the claiups. We have conchuled that the presence of a minimal 

 amount of hlood flow to the hrain was sufficient to protect these animals from 

 damage with marked reduction of cerehral blood flow at low hody temperature. 



