(xi) Sudden dyspnœa during surgical operations, due to—
(a) Mechanical obstruction to respiration, such as is caused by impaction of foreign bodies within the larynx (tooth-plates, teeth, blood, pus, vomited food, &c.), by faulty position of the head or falling backwards of the tongue, by a swollen condition of the larynx, by tumours or abscesses (retropharyngeal) which obstruct the air-way, by cicatricial contraction of the pharynx or larynx, by paralysis of the vocal cords, or by spasm of the muscles of the jaws so often associated with a similar condition of the glottis and auxiliary muscles of respiration. In a case reported by Boyle, a well-nourished muscular man was anæsthetized for the operation of internal urethrotomy; considerable difficulty was encountered with his breathing, and only towards the end of the operation was it discovered that he had well-marked stenosis of the upper opening of the larynx.
The entrance into the larynx of vomited food or blood is certainly dangerous, and may occur during the simplest operations even when properly performed, as, for instance, during removal of tonsils or adenoids. It is more likely to occur if the patient has not been prepared for an anæsthetic, or if the latter be badly administered, if the laryngeal reflex be lost, if the patient be in a bad position or suddenly moves, or if the surgeon allows too much blood to collect in the pharynx.
(b) Failure of respiration from an overdose of chloroform or other anæsthetic. To remedy such conditions it is essential that the air should be expelled from the chest as rapidly as possible. Artificial respiration can only be successful when the air passes freely both into and out of the lungs: in rare instances there may be so much difficulty in maintaining a free passage that tracheotomy should be performed.
(xii) Multiple papillomata of the larynx. Here tracheotomy is required for the relief of dyspnœa and as a preliminary to other operations. It has also been suggested as a method of curing the papillomata by giving rest to the larynx. After the performance of tracheotomy the congestion is relieved and the growths decrease in size; in some cases they completely disappear, but the treatment is uncertain and not to be recommended (see [p. 485]).
(xiii) Malignant disease of the pharynx or larynx which is too advanced for other forms of treatment. Palliative tracheotomy may be employed in order to relieve dyspnœa or as a means of giving rest to the larynx. It is most commonly used for cases of extrinsic carcinoma of the larynx: thus C. Jackson reported twenty-nine such cases, in twenty-one of which he advised palliative tracheotomy and in only eight laryngectomy. Of the former, tracheotomy was actually performed in nine, but none of the patients lived for more than thirteen months. It seems doubtful whether tracheotomy has any marked effect in retarding the course of malignant disease, though it sometimes gives relief.
(xiv) Foreign bodies in the air-passages. It makes no difference what views are held as to the advisability of tracheotomy in the treatment of these cases. The fact remains that the first essential is the safety of the patient, and, if the dyspnœa is urgent, relief must be afforded. When a foreign substance has been inhaled the surgeon must always be prepared for tracheotomy, and it is not advisable for him to leave the patient, even for a short interval, without proper supervision. In addition, the operation has been advocated as the proper treatment for all cases of foreign bodies in the lower air-passages: nevertheless, removal by Killian’s method gives far better results (see [p. 559]).
(xv) As a preliminary to operations upon the upper air-passages tracheotomy is rarely necessary, its place having been taken by infrathyreoid laryngotomy: it is, however, often performed before undertaking the larger operations upon the larynx (see [p. 489]).
Anatomy. The length of the trachea of an adult is about 4½ inches, of which 2½ inches lie above the level of the sternum; the cervical portion, which consists of eight or more rings, extends from the cricoid cartilage above to the suprasternal notch below. In order to determine the upper limit of the trachea it is advisable to palpate the following structures, which lie in the middle line, from above downwards: namely, the hyoid bone with its greater cornua, the thyreoid cartilage which forms the greatest prominence on the front of the neck, and the cricoid cartilage; in this manner it is possible to detect whether there is any deflexion of the trachea from the middle line as the result of a tumour lying in one side of the neck.
The anterior border of the sterno-mastoid muscle on each side is also an important landmark; the two muscles approach each other as they descend to their attachments to the sterno-clavicular joints, thus forming an angle the position of which corresponds to the notch in the manubrium sterni. By drawing a line transversely across the cricoid cartilage to the anterior borders of the sterno-mastoid muscles, a triangular space is marked off which may be described as the tracheotomy triangle ([Fig. 264]).