698 GENEEAL THEEAPEUTIC MEASURES 



Extensive counter-irritation causes the breathing to become 

 slower and deeper by reflex stimulation of the respiratory 

 centre, and also by making the respiratory movements more 

 painful, if the application be made to the chest vyall. The 

 circulation is likewise affected by stimulation of the vagus 

 and vasomotor centres, and both the force of the heart and 

 blood pressure are increased, unless the irritation is very 

 ■^videspread and severe, when the reverse happens. The ab- 

 dominal vessels are those constricted ; the vessels of the skin 

 and limbs are unaffected. In accordance with the foregoing 

 remarks, the use of considerable heat, together with mustard 

 or turpentine, is of great value in conditions of vital depres- 

 sion, 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-irritation 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 remote inflammation lies not 

 so much in their bringing 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 depression of the heart and heat centres, and 

 because more blood flows through the peripheral vessels 

 owing to constriction of the vessels in the abdominal organs. 



Counter-irritants notably relieve pain. This result is 

 not only due to overcoming congestion, but occurs when pain 



Digitized by Microsoft® 



