The Effect of Hypothermic States upon Reflex and Central Nervous System Activity *

Deaths from exposure to cold in the United States totalled 287 in 1932, 319 in 1933. Every year many individuals are found in a critical hypothermic state, in which there are changes in the nervous control of the body that characterize the condition and are significant in therapy. Studies have been made of monkeys,5 cats2 6 and guineapigs2 which were anesthetized and placed in a cold environment (40-46° F.). The present data are an outgrowth of the finding that the body temperature of rats,3 mice, and kittens can be rapidly reduced without the necessity of anesthetization until no organ of the body remains above 550 F. Unanesthetized animals were examined for reflexes and reactions at 10 F. intervals during the fall and subsequent recovery of body temperature. A typical example of loss of body heat in the cooled chamber and spontaneous recovery upon transfer to a warm chamber (840 F.) is seen in Fig. 1.