1452 



HEAT STROKE AND HEAT SYNCOPE 



monthly mean temperature in Chicago was 78*4° F., the highest on 

 record, and 152 men and 6 women were admitted to the hospital for 

 heat stroke or heat syncope. 



etiology {vide also Chapters VI. and VII.). — The causation of 

 the disease is the action of high air temperatures associated with a 

 high relative humidity on man, which generally act during the day- 

 time, but may also have an effect at night. 



It has already been pointed out that a human being can— for a 

 short time at all events — stand a very considerable amount of dry, 

 but not moist, heat. The heat regulation of the body is disturbed 

 and the loss of heat prevented by the humidity; consequently the 

 body temperature rises. 



Haldane's experiments have shown that if the wet bulb thermo- 

 meter rises to 88° F. (31° C.) in still air, or to 93° F. (34*4° C.).in 

 air moving at the rate of 170 feet (51 metres) per minute, or to 78° F. 

 (25-5° C.) with leisurely work, some pathological effects appear 

 and the temperature of the body begins to rise. It is of interest: to 

 note that the temperature of the body, instead of rising to a certain 

 height with a given atmospheric temperature and then remaining 

 stationary, in Haldane's experiments went on rising; and in some 

 measure this corresponded with the temperature of the air. 



Thus, with reference to the rectal temperature, which is the best 

 indication of the true bodily temperature, Haldane found that with 

 a wet bulb at 89° to 90° F. the rise was 1° to 1-4° F. (0-5° to 075° C.) 

 per hour; at about 94° F. (34*4° C.) it was 2° F. C.) per hour; at 

 98° F. (36-4° C.) it was about 4° F. (2-2° C.) per hour. 



If this condition can be induced in healthy persons at rest in 

 England, it does not seem impossible or improbable that lower tem- 

 peratures may act as vigorously or more vigorously upon Europeans 

 in the tropics or elsewhere, especially if living under conditions of 

 poor bodily health and bad sanitation, or if they are improperly clad 

 or exhausted mentally or physically. Simpson, in 1914, showed 

 that Haldane's results were applicable to ordinary climatic condi- 

 tions in hot countries. 



The fact that new-comers are more apt to suffer than old residents 

 has been put on an experimental basis by Rosenthal, who has shown 

 that a kind of active immunity to heat can be established by repeated 

 exposure of an animal to a temperature lower than that which 

 would have been fatal. These animals, when subsequently exposed 

 to a very high temperature, do show symptoms, but they are less 

 marked; the rise in temperature is not so high, the respirations 

 and the pulse not so accelerated, and the general distress less. 



The effect of clothing, load, and work has been calculated by 

 Zuntz and Schumburg, who estimate that a resting soldier weighing 

 70 kilogrammes produces from i'2 to 1*3 calories per minute, and 

 when marching, with a load of 31 kilogrammes, produces 773 

 calories per minute, which will raise the temperature of the body 

 1° C. in 87 minutes. Under ordinary circumstances the soldier 

 is not affected, but if he is wearing thick, tight-fitting uniform 



