164 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



^1 L.V. O2 Consumption 

 I I L.V. Efficiency 



Fig. 4.— Oxygen consumption of left ventricle measured by A-V oxygen differences across the 



coronary circulation. 



rewarming was started so that the animal could be considered virtually free of the 

 effects of drugs and of any significant surgical stress. As he stated, no special hazards 

 during the warming period were encountered except that transfusion induced ven- 

 tricular fibrillation if performed rapidly, but not if performed slowly. This suggests 

 a possible cardiac disability, in spite of which recovery occurred. 



Dr. Swan's data on patients suggest a more hazardous state of the circulation 

 during the rewarming stage. Is this, like Dr. Millikan's observations on the myo- 

 cardium, a direct consequence of the hypothermia or of some other factor? What 

 bearing has the surgical procedure itself or the anesthetic upon them? Would the 

 cooled lieart during the return toward normal temperature be any freer of these 

 dangers if the effects of drugs used before and during operation including the 

 anesthetic were excluded ? 



