178 PHYSIOLOGY OF INDUCED HYPOTHERAIIA 



going surgery under general anesthesia at normal body temperature have l)een 

 included in this study for comparison with the hypothermia cases. The peripheral 

 17-hydroxycorticoid levels in these patients were followed as a part of a study of 

 endocrine responses to anesthesia. 



In the patients studied, the peripheral corticoids also revealed a constant level 

 during the course of surgery under hypothermia. These steroid values are different 

 from those obtained in the experimental animal in that the patients were not sub- 

 jected to surgical stress prior to cooling. In these cases, the stress response pro- 

 voked by anesthesia per se was not marked. With cooling, and during extensive 

 surgery, there was no rise in corticoid levels. Furthermore, the values remained 

 within the normal range for several hours after completion of rewarming. A post- 

 surgical rise did occur as revealed by samples obtained within the next 12 hours. 

 However, in all cases, the magnitude of response was less than that expected from 

 the degree of surgical trauma that took place. 



The usual pattern of 1 /-hydroxy corticoids during anesthesia and surgery at nor- 

 mal body temperature is characterized by an initial steep rise with induction of 

 anesthesia, reaching levels 4 to 6 times the resting value. Peak levels are generally 

 reached within 2 to 3 hours following the conclusion of the operation. Thereafter, 

 a sharp fall occurs with normal values again present 24 to 73 hours later. This type 

 of response has been recorded in numerous patients undergoing abdominal surgery 

 with pentothal-ether anesthesia. 



Summary. 1. The peripheral arterial level of plasma 17-hydroxycorticoids has 

 been presented in dogs subjected to laparotomy before and during hypothermia. 

 The effect of exclusion of the liver from the circulation was determined. 



2. The peripheral venous corticoid levels were followed in a small group of 

 patients subjected to surgery under hypothermia and compared with the response 

 to surgery in normothermic patients. 



3. The dogs and patients revealed constant peripheral corticoid levels with ex- 

 tensive surgical trauma during hypothermia. 



4. Hypothermia with the concomitant reduction of body metabolism simultane- 

 ously depresses production and conjugation of the steroid hormones and to a 

 similar degree. 



5. A post-surgical rise in peripheral corticoids does occur but the magnitude is 

 less than that expected with comparable major surgery performed at normal 

 temperature. 



6. The function of the liver in conjugation of steroids during hypothermia is 

 depressed. 



7. Immersion cooling does not provoke a stress response as measured by pe- 

 ripheral 17-hydroxycorticoids. 



DISCUSSION 



Dr. Jean Cahn: The problem is to compare in different methods of hypothermia 

 the reaction of the adrenal and of the pituitary during stress reaction or during 

 cooling of the body. 



Here is the evolution of the ascorbic acid level of the adrenal in rats during 

 artificial hibernation. You could see during the presentation of the paper on cortico- 

 steroid secretion of the adrenals during the cooling of the body that the initial re- 



