Inferior tracheotomy demands that the external incision be free. In children, and in adults with a short neck, it should extend from the cricoid cartilage to just above the sternum. The subsequent steps of the operation are as for superior tracheotomy, with but slight differences. The anterior jugular veins may come into view, but can generally be avoided. If they are joined by a transverse branch, this is necessarily cut through after being doubly ligated. After the thyro-hyoid muscles are separated, the rings of the trachea are much less distinctly felt at first than in superior tracheotomy, being covered by more connective tissue and numerous veins. These inferior thyroid veins, especially if large, are the great obstacle in the way of this operation, and much care is necessary in order to avoid them, which should be done if possible. The lower edge of the isthmus of the thyroid gland, which presents to a variable extent above in the wound, does not, as a rule, offer any obstruction. The thymus gland present in infants is easily pulled downward and out of the way. The trachea at length fairly exposed and all bleeding controlled, the left fore finger of the operator is placed in the lower angle of the wound to securely protect the large blood-vessels here located, and the incision made through some three tracheal rings from below upward.
It may happen that in either a superior or inferior tracheotomy no time will be allowed for careful and slow dissection as here described. In such instances Durham advises that the surgeon grasp the trachea between the fore finger of his left hand on the left side and the thumb on the right, and make uniform, steady, deep pressure, thus firmly securing it and at the same time protecting the large vessels of the neck. The fingers thus placed are not to be moved until the trachea is reached, which is accomplished by rapid incisions confidently made. The pressure of the fingers causes the wound to gape and the trachea to advance. The latter reached, it is caught by the tenaculum and the operation completed as before described.
The operation of median tracheotomy may require a word. As has been stated, that part of the trachea covered by the isthmus of the thyroid gland is very commonly encroached upon in performing either or both superior and inferior tracheotomy, the isthmus being slightly displaced from its site. Other than this the site here mentioned would rarely be selected as the point for opening the trachea. Certain conditions, it is true, might render it necessary, but they would be rare. The danger lies in the hemorrhage which, theoretically at least, is to be expected when the isthmus of the thyroid gland is either torn or cut through; but opinions vary very greatly as regards this danger. With a thin, narrow isthmus in children I have frequently, in performing superior tracheotomy, cut my way through to a sufficient extent to clear a suitable space upon the trachea through which to introduce a tube without difficulty or danger. I should not recommend the procedure, however, were the isthmus to be seen to be, when reached, thick, wide, and exceedingly vascular, but at the same time believe that the danger even here of cutting into it is much overestimated.3 Roser's recommendation to apply a ligature to the isthmus on either side of the median line previous to its division is not generally applicable. Hueter has shown that the fibrous capsule of the thyroid gland enclosing it and its blood-vessels is firmly attached to the trachea and sides of the larynx, and that from the isthmus this fascia extends upward over the larynx (fascia laryngo-thyroidea), and thus prevents, in a measure, attempts at displacing the gland downward. Bose4 recommends that this fascia be divided transversely over the anterior convexity of the cricoid cartilage, when a director can be passed behind the isthmus, to lift it from the trachea and depress it far enough to expose three or four of the rings: the capsule of the gland thus remains unbroken and no hemorrhage occurs. The procedure certainly merits trial; twice it has succeeded well in my hands.
3 See Foulis, "Some Points on Tracheotomy," Glasgow Med. Journ., vol. xv. No. 2, p. 123.
4 Archiv für klin. Chirurgie, vol. xiv. p. 137.
Cricotomy, the division of the cricoid cartilage alone, is an operation which, as far as I am aware, is rarely ever performed. The objection urged against it, however, that in the adult the elasticity of the cricoid cartilage is so great that a wound through its ring cannot be made to gape sufficiently to allow of the introduction and retention of a canula without discomfort and danger of necrosis of the cartilage, is not borne out by experience. In children the objection cannot of course be urged.
The description of the operative steps which has been given, and which comprises the routine in an ordinary and easy cure, should not mislead. The operation is not always as simple and safe as would appear from what has been said. At times complicated and difficult, at times dangerous in practice from the delay involved, it demands in all, but especially in certain urgent cases, a trained hand and eye, sound anatomical knowledge, coolness, self-reliance and presence of mind on the part of the operator. Despite the greatest caution, and even in apparently favorable cases where time for dissection and deliberation is allowed, certain mishaps may occur which complicate the operation to a serious, dangerous, or even fatal degree. Some of these, as will be seen, are avoidable with care, but others may happen that are not only unavoidable, but totally unforeseen, and from their very suddenness all the more embarrassing.
Accidents may occur during the dissection of the soft parts overlying the larynx and trachea, and the importance of carefully determining by palpation the location of the various parts prior to making the preliminary incision, and of studiously preserving their relation and location during the dissection, cannot be overestimated. Neglect of this precaution has in more than one instance led to the air-passages being opened through the thyroid cartilage or thyro-hyoid membrane, instead of at the intended point. It should not be forgotten also that the natural laxity of the several layers of connective tissue of the neck is much increased by their division, and that the trachea, being naturally freely movable, is thus very easily displaced from its normal position during the act of dissection; especially will this happen when unskilful attempts are made to hook aside or retract the divided structures during the operation. Thus it may easily occur that the entire trachea is drawn to one side and entirely lost, or, more commonly, is turned upon its vertical axis, and finally opened at the side instead of anteriorly in the median line. It may not be opened at all, either being altogether missed by the surgeon in his dissection, which is continued past it, even down to the vertebral column, or the tracheal tube may be passed into the tissues lying in front of the trachea, under the mistaken idea that the latter has been incised. Persistence in keeping to the median line during dissection—a golden rule in the operation of tracheotomy—will render the first accident impossible; the second may be avoided by hooking up the trachea, as has been described, before incising it. If the opening into the trachea has not been made large enough to receive the tube, as often happens to the young operator, and even to the experienced when he fears to extend his incision on account of the proximity of the thyroid isthmus, no resource remains but to carefully enlarge it, pushing the thyroid isthmus or veins from before the course of the knife. If the opening be small, and be lost both to touch and sight, a second should at once be made, especially in urgent cases, and no time lost in searching for the first. This opening must be made directly in the median line, otherwise the canula will stand awry in the wound and be easily dislodged from its position in the trachea. If the first opening made is faulty in this respect, it is better to at once make a second. It may seem unnecessary to warn the surgeon against thrusting his sharp-pointed bistoury too far inward at the moment of incising the trachea; but as a matter of fact it has been driven through both anterior and posterior walls, and even through the oesophagus, until it has struck the spine. The converse, or a too superficial incision, is an accident more likely to occur, the point of the knife not being made to penetrate the mucous membrane of the trachea, which is probably swollen and thickened. No relief in such cases follows the incision, and an attempt to introduce a tracheal tube may cause it to pass between the mucous membrane and tracheal walls into the submucous tissue, thus stopping up the tube as it progresses. The disastrous result of such an accident can readily be foreseen unless the complication be quickly appreciated as to its nature, the tube withdrawn, and the incision completed. Much more frequently will a somewhat similar accident occur in the operation of tracheotomy for croup or diphtheria. The pseudo-membrane overlying the walls of the air-passage is not penetrated, but pushed before the knife, which has properly incised the walls of the tube; the introduction of the canula now crowds this membrane still farther back toward the posterior tracheal wall, and a complete tracheal stenosis is added to the pre-existing laryngeal one; sudden and urgent dyspnoea follows, and prompt relief alone wards off fatal suffocation. Fortunately, in such instances the forcible efforts at respiration and struggles of the patient are often sufficient to break through the occluding membrane and allow the respiratory current to pass. Violent cough often follows, and more or less of the membrane is forced out through the tube. Should these events not come instantly to pass, the surgeon must not wait for the efforts of the patient, he being often cyanosed and unconscious at this point, but by passing an elastic catheter down through the tracheal tube break through the occluding membrane forcibly. The occurrence of such an accident is always denoted by absence of respiration through the canula and by alarming asphyxia, and its cause needs but little reflection to be appreciated.
Much the same train of events happens if during the introduction of the canula large portions of the false membrane are completely detached and drawn down into the lower trachea by the violent inspiratory efforts of the patient, or stripped up from the mucous membrane and pushed downward into the air-tube. No time should be lost in either case in removing the tracheal tube, dilating the tracheal wound by forceps or otherwise, and in endeavoring to clear the trachea by seizing the obstructing membrane with forceps. If this be unavailing, the suction-syringe must be adapted to the mouth of the canula and the trachea cleared by aspiration. A large elastic catheter may take the place of the canula. Sands recommends in such instances as the foregoing that another opening should be freely made below the first one in the trachea, when respiration will probably be re-established. The success of this procedure of course depends upon the depth to which the false membrane has been drawn in the trachea.
Schüller regards the moment at which the trachea is opened as the most important and most dangerous of the whole operation. Certain of the accidents which may occur at this period have been detailed; others remain to be spoken of, one of which at least—viz. hemorrhage—requires special mention. Even before the tube is cut into it may cause an important question to arise for the surgeon's decision. A bleeding, often copious and persistent, which arises during the course of the operation from the accidental or unavoidable wounding of the thyroid veins, especially when they are large and numerous, the patient unruly, and perhaps with a short fat neck, and the fact that having wounded one the blood flows so over the parts as to obscure and increase the chance of wounding others, constitutes one of the commonest difficulties met with in the operation of tracheotomy. Hemorrhage arising from a wound of the thyroid isthmus is much rarer, and neither, as a rule, need be feared if due care and promptitude be exercised. But should it occur in a case in which the urgency of the dyspnoea allows of no time in which to employ the ordinary methods by ligature, torsion, pressure, or otherwise of checking it, shall the incision be made and the risk boldly incurred of blood passing to a dangerous degree into the trachea, and this in the face of the oft-repeated advice—the, in some quarters, absolutely given rule—that the trachea is never to be opened until all hemorrhage has ceased? I hold that it unquestionably should be, and that he who waits in many instances until the former moment will have to wait until his patient is dead. Durham truly says that it is useless to let the patient die from suffocation while attempting to prevent death from loss of blood; and yet this has been done.