[309] CHAPTER XXXIX—DECANNULATION AFTER CURE OF LARYNGEAL STENOSIS
In order to train the patient to breathe again through the larynx it is necessary to occlude the cannula. This is best done by inserting a rubber cork in the inner cannula. At first it may be necessary to make a slot in the cork so as to permit some air to enter through the tube to supplement the insufficient supply obtainable through the insufficiently patulous glottis, new corks with smaller grooves being substituted as laryngeal breathing becomes easier. Corking the cannula is an excellent orthopedic treatment in certain cases where muscle atrophy and partial inflammatory fixation of the cricoarytenoid joints are etiological factors in the stenosis. The added pull of the posterior cricoarytenoid muscles during the slight effort at inspiration restores their tone and increases the mobility of all the attached structures. By no other method can panic and spasmodic stenosis be so efficiently cured.
[FIG. 111.—Illustration of corks used to occlude the cannula in training patients to breathe through the mouth again, before decannulation. The corks allow air leakage, the amount of which is regulated by the use of different shapes. A smaller and still smaller air leak is permitted until finally an ungrooved cork is tolerated. A central hole is sometimes used instead of a slot. A, one-third cork; B, half cork; C, three-quarter cork; D, whole cork.]
Following the subsidence of an acute laryngeal stenosis, it is my rule to decannulate after the patient has been able to breathe through the larynx with the cannula tightly corked for 3 days and nights. This rule does not apply to chronic laryngeal stenosis, for while the lumen under ordinary conditions might be ample, a slight degree of inflammation might render it dangerously small. In these cases, many weeks are sometimes required to determine when decannulation is safe. A test period of a few months is advisable in most cases of chronic laryngeal stenosis. Recurrent contractions after closure of the wound are best treated by endoscopic bouginage. The corks are best made of pure rubber cord, cut and ground to shape, and grooved, if desired, on a small emery wheel (Fig. 112). The ordinary rubber corks and those made of cork-bark should not be used because of their friability, and the possible aspiration of a fragment into the bronchus, where rubber particles form very irritant foreign bodies.
[FIG. 112.—This illustration shows the method of making safe corks for tracheotomic cannulae by grinding pure rubber cord to shape on an emery wheel. After grinding the taper, if a partial cork is desired, a groove is ground on the angle of the wheel. If a half-cork is desired half of the cork is ground away on the side of the wheel. Reliable corks made in this way are now obtainable from Messers Charles J. Pilling and Son.]