INTRATRACHEAL INJECTION. 175 



the needle, the fluid slowly injected, and the needle withdrawn ; by 

 softly stroking the skin, the injection is dispersed over a larger area in 

 order to promote rapid absorption. 



3. Intratracheal injection is practised for the purpose of treating 

 disease 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 haemor- 

 rhagica and ha^moglobinuria. 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 

 does not heal aseptically, and although in healthy animals little need 

 be feared, yet, should inflammatory action set in, as may readily occur 

 in purpura, serious consequences may follow ; recent experience shows 

 that gangrene 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 during the animal's struggles 

 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 maybe made with a speciall\' large ordinary 

 syringe provided with stout needles, 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 Angers 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. In horses, from 7 to 8 

 fluid drachms may thus be administered. 



Dieckerhoff also recommends intralaryngeal and mtrapharyngeal 

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

 needle, with its concavity 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 recommends subnitrate of bismuth or 

 I per cent, iodine solution (Lugol's solution) repeated every few days. 



