INTEA-TEACHEAL INJECTIONS. 647 



than to make the puncture with the needle attached to the piston. 

 If, while injecting, we see a bubble of air in the piston, we should 

 avoid injecting it, by taking caj:e not to press the piston " home." 



By the Windpipe. 



According to this (intratracheal) method, the medicine is 

 injected by the syringe into the windpipe. The puncture should 

 be made well away from the larynx, and in the space between two 

 adjacent cartilaginous rings of the windpipe, and is generally 

 effected by a curved trocar and cannula. On removing the trocar, 

 the nozzle of the syringe is fixed to the cannula, the end of which 

 should point downwards. The mucous membrane of the windpipe 



Pig. i6l. — Hypodermic syringe. 



is not very sensitive, probably on account of its great power of 

 absorption. The amount of solution niay vary from |^ to 1 oz., 

 and the fluid should be slowly injected, so as not to interfere with 

 the breathing. The nature of the fluid and the precautions as to. 

 cleanliness are similar to those in subcutaneous injections. Beyond 

 a slight gain in time, intratracheal injections, other than those 

 intended to act locally, have no advantage over hypodermic 

 injections. This statement does not hold good with respect to 

 quinine, a solution of which is readily absorbed by the windpipe 

 and without producing irritation, as it is apt to do if injected 

 subcutaneously. 



By Puncture into the Large Intestine. 



The bowel is first pimctured by a trocar and cannula, and 

 when the trocar is withdrawn, the medicine is injected into the 

 cannula, which conveys it into the intestine. Observe the 

 precaution that the cannula is still in the bowel when the solution 

 is injected. This is shown by a small amount of gas being expelled 

 with each respiratory movement. If the solution, instead of 

 flowing into the bowel, falls into the abdominal cavity, death may 

 ensue from peritonitis (p. 114). The danger (p. 689) of this 

 accident naturally decreases the popularity of this operation. 



