气管切开术（图文演示）

中文版：气管切开术（中文图文演示）

TRACHEOSTOMY
Authors
A Stefani, D Gossot
Abstract
The description of the tracheostomy covers all aspects of the surgical procedure used for the management of upper airway obstruction.
Operating room set up, position of patient and equipment, instruments used are thoroughly described. The technical key steps of the surgical procedure are presented in a step by step way: skin incision, approaching the trachea, tracheal incision, inserting the cannula, closure.
Consequently, this operating technique is well standardized for the management of this condition.

1. Introduction
Tracheostomy is a surgical procedure with very ancient roots. Galen first described the technique as an invention of Aesculapius, but the procedure was not really used through the centuries because of the associated high mortality.
Trousseau was the first to report good results with this technique, using it to save the lives of approximately 50 infants with diphtheria.
Despite this, tracheostomy was not accepted as routine treatment until the 1920s, when Chevalier Jackson standardized the techniques and indications for the procedure.

2. Surgical anatomy

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A tracheostomy is performed in the anterior triangle of the neck.
The borders of this triangle are:
- superiorly, the mandible;
- inferiorly, the suprasternal notch;
- laterally, the anterior borders of the 2 sternocleidomastoid muscles (SCM).

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The upper airway is the principal anatomical structure in this region.
It is a midline structure that extends cephalad to caudad, in an anterior to posterior
trajectory, from the larynx to the cervical trachea.
As a result, the larynx lies in a more anterior position than the cervical trachea, and access to it is more difficult.

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With the head in extension, one can palpate from superior to inferior:
- the thyroid cartilage, which is the most prominent structure in the midline;
- the cricoid cartilage;
- the cervical trachea, where the tracheal rings can be distinguished in a thin person;
- the suprasternal notch.
With the head in the normal position, 7 to 10 tracheal rings are evident.
With the head in flexion, the cricoid cartilage is pressed against the suprasternal notch.
With the head in extension, some of the tracheal rings that are usually in the thorax become accessible in the neck.

• Anterior view

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1. Skin and subcutaneous tissue
2. Platysma muscle

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3. The superficial cervical fascia is formed by the fascia of the SCM muscles.
4. The deep cervical fascia is formed by the fascia of the infra-hyoid muscles (the sternohyoid and omohyoid muscles). The sternothyroid muscles are nearer to the midline.

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5. The visceral or pretracheal fascia covers the trachea and thyroid gland.

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6. The isthmus of the thyroid is a midline structure situated on the anterior border of the trachea, extending from the second to the fourth tracheal ring (depending on the patient). The thyroid lobes are approximated to the lateral borders of the trachea.

3. Blood supply/innervation
• Blood supply

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- the anterior jugular veins: they course downward laterally, on the sternohyoid and SCM muscles. They are joined by several thin branches;
- the transverse jugular vein: not a constant feature, it crosses the midline;
- the inferior thyroid veins: they originate from the inferior pole of the thyroid and descend on the anterior or lateral border of the trachea;
- the isthmic vessels: the small arteries and veins of the capsule or parenchyma.

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Situated further from the dissection field:
- the brachiocephalic trunk, which is situated on the trachea behind the manubrium;
- the common carotid arteries, running lateral and deep in the neck.
The arteries supplying the trachea course along the postero-lateral border, and are therefore not encountered during the anterior dissection.

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The larynx and the trachea are situated in front of the esophagus.
The recurrent laryngeal nerves run along the posterior lateral border of the trachea.

4. Indications
Indications
- upper airway obstruction;
- mechanical ventilation;
- tracheo-bronchial toilet;
- prophylactic tracheostomy.

Contraindications
Emergency tracheostomy is not a contraindication.

Relative contraindications
- recent surgical procedure on the neck (this is not accepted by all authors),
- soft tissue inflammation of the neck.

Absolute contraindications
- severe coagulation disorder or disseminated intravascular coagulation (DIC),
- patients on anticoagulant medication.

5. Operating room set-up

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Elective tracheostomy should be performed in an operating room under aseptic conditions, with a full set of instruments and good lighting. An anesthesiologist and ECG monitoring are used.

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- general anesthesia is advisable: local anesthetic solution can be infiltrated to complement the effect of the general anesthetic. This decreases the need for analgesia, elevates tissue planes for easier dissection, and reduces the tracheal reflexes during introduction of the tracheostomy tube;
- endotracheal tube and ventilation;
- supine position;
- arms by the sides;
- neck stabilized and fixed in the midline;
- sandbag under the shoulders to place the neck in hyperextension. This can be accentuated by dropping the head of the table. However, excessive extension can cause the tracheostomy to be placed too low.

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1. The surgeon stands to the right of the patient.
2. The assistant stands to the left of the patient.
3. The scrub nurse stands to the right of the surgeon.
4. The anesthesiologist stands at the head of the patient.

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1. Operating table
2. Anesthetic unit
3. Electrocautery

6. Instruments

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Complete sets containing all the necessary instruments and tracheostomy tubes are available commercially.

• Operating instruments

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1. Standard dissecting forceps
2. Metzenbaum dissecting scissors with curved tip.

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1. 10 mL syringe for inflation of the tracheostomy cuff
2. Band for fastening
3. Trocar tip
4. Connection tubing for the ventilator

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1. Halsted-Mosquito forceps
2. Standard needle holder
3. Kelly forceps

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1. Beckmann-Adson self-retaining retractor
2. Farabeuf retractors
3. Laborde dilator (3 blades)
4. Trousseau dilator (2 blades)

7. Skin incision

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The incision can be vertical or horizontal, depending on the surgeon’s preference.
Before incision of the skin, the following landmarks should be identified by palpation:
- the thyroid and cricoid cartilage;
- the anterior borders of the SCM muscles;
- the suprasternal notch.
For the purpose of this description a horizontal incision is used.
Further dissection after opening the skin is identical for the 2 incisions.

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This can be made from the inferior border of the thyroid cartilage to the manubrium.
It is used where there has been a previous cervical incision or in urgent cases.
Very easy and quick, as dissection is reduced to a minimum, it is not as aesthetically pleasing as a horizontal incision.

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It is made 2 fingerbreadths above the suprasternal notch or a fingerbreadth below the cricoid cartilage, usually in a skin crease.
In all cases, one should be careful not to make the incision less than one fingerbreadth above the sternal notch. It is made transversely from the anterior border of one SCM muscle to the other. This also applies to the subcutaneous tissue and platysma up to the superficial cervical aponeurosis.

8. Approaching the trachea I

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The dissection plane should always be vertical.
The surgeon should constantly verify by palpation of the thyroid cartilage that the dissection tract is not deviating laterally, but staying in the midline. A self-retaining retractor can be used to keep the incision open.

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The superficial cervical aponeurosis is incised with scissors in a longitudinal plane, extending upward from suprasternal notch to the cricoid cartilage. It is the length of this incision and not the skin incision that determines the extent of tracheal exposure.
It may be necessary to dissect out and ligate the anterior jugular or transverse jugular veins with a slowly absorbable suture.
Additional local anesthetic can be infiltrated during this stage of the dissection.

9. Approaching the trachea II
• Thyroid isthmus dissection

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The infra-hyoid muscles are dissected. After incision of the aponeurosis, the muscles can be retracted.
This dissection exposes the anterior border of the trachea, as well as the isthmus of the thyroid, which appears purplish.
In urgent cases, one may not have time to formally divide the isthmus.
In cases with a very large isthmus, dividing the isthmus may be the only option.
Apart from the above, the experience and preference of the surgeon will determine how the isthmus is managed.

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The isthmus of the thyroid may be divided. This makes the procedure much more invasive and the risk of hemorrhage is greatly increased. However, a tracheostomy through the divided isthmus provides direct access to the anterior surface of the trachea.
This part of the procedure is done in 3 stages:
- dissecting out the isthmus;
- dividing the isthmus between 2 forceps;
- ligating the isthmus with a slowly absorbable suture.

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This alternative consists of retracting the isthmus downward (supra-isthmic approach) or upward (infra-isthmic approach).
An intact isthmus may add to the difficulty of changing the cannula, because the isthmus may move and obstruct the tracheal orifice. In addition, there is a risk of secondary hemorrhage from erosion of small vessels in the isthmus by the tracheostomy cannula.

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Whether the tracheostomy is infra-isthmic or supra-isthmic, one should be careful not to incise the trachea too low or too high, respectively.