REVIEW AND APPRAISAL OF PARTS I AND II— SEVERINGHAUS 283 



protect the kidney partially to 2 hours of ischemia. Creatinine and ammonia pro- 

 ducticjn are drastically reduced at low temperatures. 



Endocrine. Hypothermia appears ca])al)le of larj^ely blocking the usual adrenal 

 response to trauma. ACTH, 17-hydroxycorticosteroids and cortic(nds are all 

 greatly depressed at 25-28° C. Epinephrine outinit is reduced 10- fold at 26° C. 

 and 100-fold at 21° C. Although the current tests for these substances are some- 

 what gross, the major changes reported seem significant. One discussant felt that 

 the adrenal cortical response to ACTH was not completely l)locked above 25° C. 

 It is suggested that hypothermia patients do not show the usual jjostoperative 

 endocrine stress i)attern of overshooting the normal levels of corticoids. Patients 

 who cannot summon an endocrine response to trauma do very poorly, and it may 

 be that some of the immediate postoperative circulatory difficulties in i)atients fol- 

 lowing hypothermia may be related to this depression of adrenal response. For 

 the most part, however, it appears to be a welcome depression of the occasionally 

 excessive postoperative endocrine reaction. 



The endocrines appear to play a significant role in natural hibernation. The 

 adrenal and thyroid involute before hibernation, and recent evidence ( Brewster 

 ct al., Circulation. Jan. 36) (not presented at the conference) suggests that the basal 

 metabolism raising effect of thyroxine re([uires the presence of circulating epineph- 

 rine. This provides the needed link in the nervous system control of heat pro- 

 duction in hibernators. 



Electrolytes. It now seems that during hy]X)thermia tissues do not lose 

 potassium as was formerly thought, but more than likely they actually take up 

 potassium. This was found true in the heart both with general hvpothermia. and 

 with the perfusion of cold blood into one coronary artery. Hyperventilation at 2)7° 

 may depress serum potassium 30%, whereas during hypothermia the depression 

 from hyperventilation is given as \S'/( . This of course depends upon the vigor 

 of the ventilation. Rise in serum potassium is promoted by hypoventilation, shiver- 

 ing, glycogen breakdcnvn and increased metabolism. All but one investigator found 

 calcium to rise as temperature fell. ^Magnesium in hibernators is said to rise 50%. 

 ( )ther electrolvte changes seem insisrnificant. 



