DANGERS OF TRACHEOTOMY. 
203 
The tube gradually becomes stopped by secretion from the mucous membrane 
and the operation wound, and must, therefore, be frequently cleansed, at first, 
indeed, daily. As the secretion diminishes, cleansing is required at intervals 
of three or four days. Hence it is well to have two similar canulse, so that 
whilst one is in use, the other can be cleansed or, if need be, repaired.. Such 
precautions are necessary, because the wound contracts very rapidly ; indeed, 
after the lapse of an hour or two the introduction of the canula may be 
difficult, or even impossible. Whilst the horse is in the stable, the opening 
of the instrument may be stopped up with a cork, which will check secretion 
and blocking of the tube. Double tubes have been recommended to obviate 
the necessity for changing the canula. They are generally used in man (fig. 96). 
Whilst the outer tube lies in the trachea, the inner can be cleaned from time 
to time. But this form, shown in fig. 96, must be condemned, because the 
curvature of the upper part is too slight, and that of the lower part too great, 
the lower portion, as already stated, should be quite straight. In double 
tubes this curvature cannot be avoided; hence they are unsuitable, and can 
only be used where the trachea is very near the surface. This model also 
possesses another fault—its opening lies at the side. Injuries from its lower 
border are certainly thus avoided, but the lateral opening coming in contact 
with the mucous membrane, the passage of air is interfered with. 
To obviate the necessity for a canula, Strauss recommends cutting out an 
oval piece from the trachea, with precautions against injuring the mucous 
membrane, which is sutured to the skin. But Hering doubts whether this 
operation can be successfully done, and iVloller s experience tends in the same 
direction. In the absence of a canula, hooks may be introduced on eithei 
side into the tracheal opening, and held apart by tapes passed lound the 
animal’s neck. 
As a temporary expedient, the neck of a bottle, or a pair of strong 
wires bent to a spoon-handle shape, may be inserted. To save animals 
from threatened suffocation, there is often insufficient time to proceed 
according to rule. Most practitioners have on occasion been forced to 
operate in a dark stable, and, furnished merely with a bistoury, to find 
the middle line of the neck as they best could, and insert a tube. 
Despite these difficulties, the parts usually heal well. 
Krieshaber has recommended an operation under the title of “ tracheo- 
tomie sous-cricoidienne,” in which an incision is made immediately 
under the cricoid cartilage; the crico-tracheal ligament, which is about 
1 inch in breadth, divided, and a double-limbed canula introduced. The 
position of this ligament is easily discovered by palpation, especially in 
horses, where the muscles of the neck are not greatly developed. W ith 
the head extended, the operation is not difficult in quiet animals. This 
method has the advantage of only slightly impairing the animal’s appear¬ 
ance, and facilitates direct examination and treatment of the larynx, 
while the action of the tube, moreover, widens the larynx, and it is said 
that, after wearing the canula for a time, animals sometimes cease loaiing 
altogether. This may perhaps result from the irritative processes pro¬ 
duced by the canula causing anchylosis of the articulation of the arytenoid 
cartilage on the paralysed side. Bouley fears that horses thus operated 
