COLD AND HEAT 707 



clotli. The water is thrown on in considerable quantities, 

 beginning with the head and going rapidly over the neck, 

 trunk and limbs successively, rubbing the skin briskly all 

 the while with the cloth. Two attendants are required for 

 the application of an ablution to the larger animals. The 

 patient is finally dried and warmly blanketed. The process 

 may be repeated each half hour in fever, or twice daily as a 

 tonic measure in chronic diseases. The rationale consists in 

 the stimulus afforded by the cold to the nervous system, 

 accompanied by contraction and subsequent dilatation of 

 the peripheral blood vessels, with consequent cooling of the 

 blood and increased radiation of heat from the surface. In 

 most hydriatic methods for reducing temperature in fever, 

 friction of the skin should be the sine qua non, as otherwise 

 the physical cooling of the body is confined entirely to the 

 periphery, the contraction of the surface vessels driving the 

 blood inward to the vital organs. The superficial muscles 

 then act as non-conductors, and heat production being stimu- 

 lated reflexly by the cold, an actual increase of internal 

 temperature may obtain. 



It is only by securing dilatation of the superficial ves- 

 sels by friction that the result first described can be 

 prevented, for after the first shock the peripheral vessels 

 dilate, an increased supply of blood is brought to the sur- 

 face, is rapidly cooled and courses inward, only to be replaced 

 by more over-heated blood. The internal temperature is 

 thus lowered, and instead of an internal congestion being 

 brought about, as may happen when the skin is simply 

 exposed to cold, we have a constant withdrawal of heated 

 blood from the interior. In this perpetual interchange not 

 only does cooling of the blood and body occur, but the cir- 

 culation is equalized and congestions are overcome. 



The Sheet Batli.—'W'hole baths are impracticable for our 

 larger patients, and the sheet bath may be substituted to 

 advantage for antipyretic and other purposes to which the 

 cold bath is adapted. A cloth soaked in cold water, or ice 

 poultice, is placed on the poll to prevent determination of 



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