INTRATRACHEAL INJECTIONS. 177 



ceases the syringe may then be fitted to the needle, the fluid slowly 

 injected, and the needle withdrawn. By gently stroking the skin, 

 the injection is dispersed over a larger area in order to promote 

 rapid absorption. 



(c) Intratracheal injection is practised for the purpose of treating 

 diseases of the upper air-passages like chronic laryngeal or tracheal 

 catarrh, to kill parasites present in the trachea and bronchi, and as 

 a means of combating certain general disorders like purpura 

 hemorrhagica and hemoglobinuria. As absorption occurs very 

 rapidly from the tracheal and bronchial mucous membrane this 

 system of medication has a rational basis, but, as a rule, more 

 convenient and less dangerous methods deserve preference. From 

 the experiments made it has become clear that the tracheal mucous 

 membrane is far less sensitive than was formerly imagined, and that 

 irritants like tinctures and oil of turpentine are really very well borne. 

 As, however, the tracheal mucous membrane cannot be disinfected 

 the small punctured wound may not heal aseptically, and although 

 in healthy animals there is little danger, yet, should inflammatory 

 action set in, as may readily occur in purpura, serious consequences 

 may follow. Recent experience shows that necrosis of the tracheal 

 mucous membrane, and even of the lungs, sometimes occurs. The 

 needle must be cautiously inserted, and as it is sometimes subject 

 to considerable stress it should be stout in order to avoid breakage. 

 In the event of this occurring the broken fragment must at once 

 be grasped with forceps, or, if it be invisible, a cutaneous incision 

 must be made in order to detect and remove it. 



Intratracheal injections may be made with an ordinary hypo- 

 dermic syringe provided with a stout needle, with a large Pravaz 

 syringe, or with Dieckerhoff's syringe, which is used in conjunction 

 with a special trocar and cannula. The animal's head is raised, and 

 the operator, stretching the skin covering the front of the trachea 

 with the fingers of the left hand, thrusts the needle or trocar 

 through the space between two tracheal rings. Removing the 

 stilette he inserts the nozzle of the ready-filled syringe in the 

 mouth of the cannula, and slowly injects the contents into the 

 trachea. 



Dieckerhoff also recommends intralaryngeal and intrapharyngeal 

 injections. The method is similar to that above described. A 

 curved needle, with its convexity directed upwards, is passed 

 between the cricoid cartilage and the first ring of the trachea, 

 traversing the crico-tracheal ligament, and fluid is thus injected 

 into the larynx or pharynx. In chronic laryngitis Dieckerhoff 



