JAMES A. MILLER, JR. 



243 



In a limited series (20 experimentals and 20 controls), animals were 

 cooled to 20°C, severely asphyxiated, and the effects of rapid rewarming 

 in a water bath at 45 °C were compared with spontaneous recovery. Of 

 those that survived, the rewarmed animals reached each stage of recovery 

 in about half of the time required by the controls. However, since eight 

 rewarmed and nine controls failed to recover, it was concluded that 

 recovery from asphyxia in cooled animals depends largely upon the length 

 and severity of the asphyxia and that events during the subequent recovery 

 period are of lesser significance. 



Measurements of oxygen uptake before and after cooling gave a mean 

 depression of 56.8% per 20° C depression of body temperature. This is in 

 good agreement with expectation of a 50% depression if the asphyxial 



Table 3. Percentage recovery from asphyxia* 



* Condensation of table 5, Miller and Miller, 1954. 



t Mean survival time for animals which died was greater than that of controls. 



protection conferred depends entirely upon reduction in metabolic require- 

 ments (120). 



Experiments with 300-gram guinea i)igs showed that, although it is 

 not as effective as in the newborn, hypothermia prolongs asphyxial survival 

 in young adults as well (118, 127) . Figure 4 based on the time of asphyxial 

 death (T.O.D.) of 197 animals shows that temperatures below 20°C 

 become increasingly hazardous on the average. However, it is to be noted 

 that the longest survival in the series was an animal at 15.4°C who lived 

 286 seconds. This suggests that in the case of adults as well as the new- 

 born, it is the secondary effects of hypothermia which alter the picture 

 below 20°C. As a corollary it may be predicted that the maximal hypo- 

 thermic protection against asphyxia for adults will i)robably be found 

 close to 0°C when secondary effects of low temperature are controlled. 

 As in the case of the newborn, adult animals cooled 10° or 15°C recover 



