A system of practical medicine. By American authors. Vol. 3

by Unknown

² See Pilcher, "The Anatomy of the Anterior Median Region of the Neck," Ann. of Anat. and Surgery, Brooklyn, April, 1881.

It will be remembered that the trachea commences at the inferior border of the cricoid cartilage, directly opposite to the lower edge of the fifth cervical vertebra, and reaches thence downward, in the median line of the neck, until it bifurcates opposite to the third dorsal vertebra. In its upper part it is nearly subcutaneous, and is surmounted by the prominent ring of the cricoid cartilage (easily identified, even in the young child), above which, in turn, lies a slight depression (the crico-thyroid space) between the cricoid and thyroid cartilages. As the trachea descends in the neck it recedes gradually, lying at the episternal notch about one and three-eighths of an inch from the surface. Throughout the whole of this course it is in relation with important structures. In its cervical portion it is covered by the sterno-hyoid and sterno-thyroid muscles, and in the median space, which is usually distinct between them, by layers of the deep cervical fascia. It is also crossed by the isthmus of the thyroid gland, which lies between the second and fourth tracheal rings; by the arteria-thyroidea ima, when present, and below by the plexus formed of inferior thyroid veins with their tributary and communicating branches. In the latter region, but more superficially, are some communicating branches between the anterior jugular veins. The innominate and left carotid arteries are also anterior to it in the episternal notch as they diverge from their origin. Laterally, the trachea is in relation with the common carotid artery, the lateral lobes of the thyroid body, the inferior thyroid veins, and the recurrent laryngeal nerves. The thoracic portion of the trachea is covered by the manubrium sterni, with the origins of the sterno-hyoid and sterno-thyroid muscles, by the left innominate vein, and by the commencement of the innominate and left carotid arteries. Still lower, the transverse portion of the arch of the aorta crosses, and the deep cardiac plexus of nerves lies in front of it. Posteriorly, throughout its length, it rests upon the oesophagus.

In performing, then, either the superior or inferior operation of tracheotomy, after cutting through the skin and superficial cervical fascia—which is really loose areolar tissue containing fat—the superficial layer of the deep cervical fascia is reached, and immediately below it more or less adipose tissue and the two anterior jugular veins lying in an inferior tracheotomy to either side of the wound, which is always made in the median line. As a matter of fact, these various layers are rarely demonstrable, and the surgeon proceeds irrespective of them until he reaches this point in his operation—viz. the muscles which overlie the trachea. These may overlap in the median line, and have to be retracted after having been separated; or, again, a thin line of connective tissue marks a slight interval between their inner edges, and is readily seen and dissected through if the operator has kept his incision vertical and strictly in the median line of the neck—a matter so important to the success of his operation that I do not hesitate to again allude to it. The muscles separated and gently retracted, together with the overlying tissues, toward the sides of the wound, the upper edge of the isthmus of the thyroid gland overlying the second and third, perhaps fourth, rings of the trachea, is always seen in a superior tracheotomy—its lower edge very frequently in the inferior operation. The isthmus is adherent to the trachea and to the larynx through the deep layer of the deep cervical fascia, but is capable of being slightly displaced or pushed upward or downward as the case may be, and thus kept from obscuring the operative field. This being done, the deep layer of the deep cervical fascia is seen covering and strongly adherent to the tracheal wall together with the thyroid veins. A few touches of the knife, carefully avoiding the blood-vessels, serve to clear it away, and the tracheal rings are clearly exposed.

In carrying out this dissection, which has been described as occurring in an ordinary and uncomplicated adult case, several matters must be borne in mind; and especially is this true if the operation concerns infants. In them, for instance, the thymus gland rises half an inch above the level of the sternum, and is frequently to be found as late as the sixth or seventh year. In both adults and children the innominate artery occasionally comes into view in an inferior tracheotomy, obliquely crossing the lower portion of the right half of the trachea. It is relatively higher in the child than in the adult. The left innominate vein is also often observed when the trachea is opened low down.

Certain abnormalities of the blood-vessels have been alluded to above. The commonest consists in the existence of a thyroidea ima artery, which when present usually arises from the innominate trunk, but sometimes from the right common carotid or the aorta: it passes to the thyroid body directly in the median line of the neck and close to the trachea; again, the place of the anterior jugular veins may be taken by a single central vessel, almost sure to be wounded during the operation if it exist (Mackenzie).

In performing the operation through the thyro-cricoid membrane (thyro-cricotomy) or through the cricoid cartilage alone (cricotomy), the same tissues are met with, and the same dissection is necessary in the earlier stage of the operation, as have been described in the operation of superior or inferior tracheotomy; but the parts are more superficial, adipose and cellular tissue less abundant, blood-vessels much less numerous, and the operation very much simpler. The thyroid gland of course does not come into view, and the crico-thyroid artery, a very small vessel, needs no attention in the dissection.

I have here and elsewhere included under the general term tracheotomy five distinct operations, having for their object the opening of the air-passages, which are surgically possible between the lower border of the thyroid cartilage and the upper edge of the sternum. In this classification I have followed that of Schüller, and its simplicity, but exactness, and the avoidance of the old confusion of different terms which results from the use of one intelligently employed, seem to me to commend it. These five operations are—1. Thyro-cricotomy, or the opening made through the crico-thyroid membrane alone. 2. Cricotomy, or the division of the cricoid cartilage alone. 3. Superior tracheotomy, the incision being made above the point where the isthmus of the thyroid gland crosses the trachea and below the cricoid cartilage. 4. Median tracheotomy, when, the isthmus being displaced or torn through, the trachea is opened immediately below its site. And 5. Inferior tracheotomy, the incision being made below the point of crossing of the isthmus of the thyroid gland, and at varying distances, dependent mainly upon the age of the patient and size of the parts, above the sternal notch.

Rarely, I am bound to admit, is the field of all of these operations as distinctly limited in practice as is here indicated, and one, perhaps two, are rarely selected. Thyro-cricotomy (old term laryngotomy) is often indicated, and cricotomy and median tracheotomy are sometimes performed as here described. Superior tracheotomy is commonly a combination of at least two of the methods—viz. the division of the upper rings of the trachea and the cricoid cartilage as well. It may even, probably frequently does, trench also upon the thyro-cricoid membrane (thyro-cricotomy) and upon the field of a median tracheotomy, the isthmus being pushed downward or even cut or torn through. The latter operation and cricotomy are, I believe, rarely if ever done from choice. Finally, inferior tracheotomy is a common method. As here described, it meets a large number of indications, and, despite its superior difficulties over the higher operations, is therefore necessarily often chosen; not infrequently, however, does it invade the median region, the isthmus of the thyroid being pushed upward.

Which of these operations shall be selected in a given case depends upon the particular conditions which render it necessary, and likewise, to some extent, upon the age of the patient. Durham summarizes the question very fairly. Thyro-cricotomy (old term laryngotomy) is by far the easiest operation to perform, and its execution is attended by least risk; therefore it is the operation to be preferred in any sudden emergency when suffocation threatens, and especially where the surgeon is alone with the patient. Generally, it is not as applicable as the others, especially in early childhood, on account of the limited dimensions of the thyro-cricoid space. It cannot be recommended in cases of acute or extensive diseases or injuries of the larynx, nor is it likely to be of much service if a foreign body is in the trachea or bronchus. On the other hand, it is probably the best operation to adopt in cases in which foreign bodies are impacted in the larynx, in cases of limited chronic disease or contractions of the superior laryngeal parts—usually the result of syphilitic ulceration—and in cases in which respiration is impeded by intra-laryngeal growths which cannot be removed by the natural passages.

Cricotomy, combined with superior tracheotomy (old term laryngo-tracheotomy), is not a difficult operation, and may be advantageously practised, especially in children; in the adult it meets many indications. Holmes recommends it the more urgently, in preference to an inferior tracheotomy, the earlier the age of the subject may be.