HyEMOSTASIS. 



in 



Some act by causing contraction of the vessel and surrounding tissues. 

 Among those formerly employed were oak bark powder, tannin, 

 mineral acids and their salts, alum, nitrate of silver, acetic acid, 

 creosote, carbolic acid, alcohol, oil of turpentine, etc. Perchloride 

 of iron in the form of liq. ferri perchlor. diluted with three parts of 

 water is often used to moisten tampons which are applied to the 

 bleeding spot. The most popular and effective styptic is solution 

 of adrenalin, which quickly arrests bleeding from capillaries and 

 small vessels. To check bleeding resulting from internal injuries, 

 and to lessen haemorrhage during 

 operations, calcium chloride, which 

 increases the coagulability of the 

 blood, gelatinised serum, extract of 

 ergot, and hydrastis canadensis have 

 been employed with success. In 

 operation wounds powerful styptics 

 sometimes retard or prevent healing 

 by first intention, owing to their 

 caustic or astringent effect on the 

 wound surfaces. 



Surgical methods of controlling 

 or arresting haemorrhage are repre- 

 sented by the tourniquet, Esmarch's 

 bandage, and rubber cord, by com- 

 pression, ligation, torsion, forci- 

 pressure, and acupressure. As a 

 preventive, especially when operating 

 on the limbs, the application of a 

 tourniquet (Fig. 153), or a rubber 

 cord is the means usually employed. 



For the horse the most primitive 

 method consists in passing a loop of 

 cord or webbing around the limb 



and tightening it by the rotation of a stout stick slipped through 

 it. The pressure thus exercised on the vessels checks circulation, 

 and haemorrhage during operation is virtually nil, while owing to 

 compression of the nerves sensation below the ligature is dulled and 

 the pain of operation greatly diminished. 



A more refined method is to use a rubber cord or tube. A rubber 

 cord half an inch thick and twenty to thirty inches in length is 

 passed around the limb above the knee or hock in a stretched con- 

 dition. The ends are united by a simple knot or a strong cord. 



Fig. 153.— The tourniquet, 



