or T«j 



'^ or T«B ^ 



COUNTER-IRRITANTS 667 



Extensive counter-irritation causes the breathing to become 

 slower and deeper by reflex stimulation of the vagi, and 

 also by making the respiratory movements more painful, if 

 the application be made to the chest wall. The circulation 

 is likewise affected, and both the force of the heart and 

 blood pressure are increased, unless the irritation is very 

 widespread and severe, when the reverse happens. In ac- 

 cordance with the foregoing remarks, the use of considerable 

 heat, together with mustard or turpentine, is of great value 

 in conditions of vital depression, surgical shock, collapse 

 and coma. Moreover, the effect on local blood supply is 

 still greater and full of importance, since it may explain the 

 beneficial action obtained in the ordinary use of counter- 

 irritants. In experiments conducted upon animals, it has 

 been observed that when sinapisms are placed over the 

 head, the blood vessels in the pia mater are first dilated, but 

 soon contract and remain in that condition for some time. 

 Likewise there was seen, following energetic counter-irrita- 

 tion of the chest, anaemia of the underlying parts, including 

 the muscles, pleura, and even the pulmonary tissue. It is 

 essential to bear in mind, then, that while counter-irritants 

 induce local congestion in their immediate vicinity, they also 

 cause reflexly vascular contraction in more remote areas. 

 In accordance with this demonstration, the importance of 

 these agents in inflammation lies not so much in their bring- 

 ing blood to the surface, as in forcing it out of distant parts. 

 This fact is not generally appreciated. The use of the word 

 "drawing" signifies the common idea of a counter-irritant, 

 and implies the first proposition. 



Temperature is not materially affected by the therapeu- 

 tic use of counter-irritants, and they are not necessarily 

 contraindicated in fevers. Experiments, however, appear 

 to show that mild counter-irritation may lead to a slight 

 elevation of body-heat, owing to stimulation of the calorifa- 

 cient centres, while extensive and prolonged action lowers 

 temperature by diarphoresis and depression of the heart and 

 heat centres-. 



