SUPERCOOLING AND FREEZING— ANDJUS, LOVELOCK and SAIITH 129 



REFERENCES 



1. Smith, A. U. : Studies on golden hamsters during cooling to and rewarming from body tem- 



peratures below 0° C. I. Observations during chilling, freezing and supercooling. II. Obser- 

 vations during and after resuscitation, Proc. Roy. Soc, London, ser. B, 145: (I) 391-407 

 (II) 407-426, 1956. 



2. Lovelock, J. E., and Smith, A. U. : Studies on golden hamsters during cooling to and re- 



warming from body temperatures below 0° C. III. Biophysical aspects and general discus- 

 sion, Proc. Roy. Soc, London, ser. B, 145: 427-442, 1956. 



3. Smith, A. U. : Frostbite in golden hamsters revived from body temperatures below 0° C, 



Lancet 267: 1255-1259, 1954. 



ADDENDUM: 



CLOSED CONTAINER COOLING, AND OBSERVATIONS ON THE PHYSIOLOGY 



OF COOLING AND RESUSCITATION 



Furnished by R. K. Andjus 



I would like to give a summary of our recent work on hypothermia which was 

 illustrated to a certain extent by the film presented to the Conference, particularly 

 by the parts concerning the resuscitation of rats and monkeys after cooling to body 

 temperatures of 0° and 5° C, respectively. 



There are three main lines along which we have been working : 



1. the method of inducing hypothermia by changing the concentration of natural 

 respiratory gases ; 



2. the method of resuscitation from suspended animation in hypothermia by 

 preferential heating of the cardiac area, and 



3. the physiological study of the unanesthetized animal in hypothermia, includ- 

 ing the study of prolonged and repeated hypothermia as well as of the period of 

 recovery. 



TECHNIQUE OF COOLING WITHIN A CLOSED CONTAINER 



It was known since the work of Paul Bert and Raphael Dubois toward the end of 

 the last century that oxygen lack on the one hand and CO2 excess on the other are 

 capable of inducing hypothermia in animals. Giaja showed in 1940 and 1942 that 

 rats, cats, and dogs can be cooled below 20° C. body temperature by reducing gradu- 

 ally the total barometric pressure in the container in which the animal is kept at 

 ambient air temperatures of about 10° C. He showed also that rats become hypo- 

 thermic when left in hermetically closed containers and reported of a case of spon- 

 taneous recovery after such cooling to a body temperature of 8.8° C. (Giaja, 1940 

 and 1941). 



Rats cooled to about 15° C. by the closed container technique tolerate very well 

 a variety of surgical operations and this method of cooling was suggested as a 

 routine technique for inducing "physical anesthesia" (Giaja and Andjus, 1949, 

 Andjus, 1950). The greatly increased resistance to oxygen deficiency in animals 

 cooled by this technique made it particularly suitable for physical anesthesia in 

 surgery where there was danger of asphyxia (hypophysectomy in rats, for in- 

 stance) (Andjus, 1950). 



The closed container technique of cooling enabled us (1) to cool safely animals 



