12 Cricothyrotomy
Abstract
Cricothyrotomy (aka cricothyroidotomy) is an emergent procedure, performed in order to establish an airway in a patient with respiratory failure who cannot be oxygenated and ventilated via alternative measures. Here the following topics related to cricothyrotomy are discussed in detail: relevant anatomy and physiology, indications/contraindications, equipment, technique, complications, and expert suggestions.
Keywords: cricothyrotomy, tracheostomy, respiratory failure, intubation, surgical airway
12.1 Introduction
A cricothyrotomy is a temporary surgical airway, created by incising the anterior neck in the midline and inserting an endotracheal or tracheostomy tube through the cricothyroid membrane into the trachea. It is performed in the emergent setting of life-threatening respiratory compromise in a patient who can be neither intubated nor ventilated via alternative measures.
12.2 Relevant Anatomy and Physiology
Successful cricothyrotomy relies on a basic knowledge of the surface anatomy of the anterior neck and the underlying laryngeal structures. In the midline, several important landmarks are usually palpable. The hyoid bone can be felt as a hard but mobile arch just below the angle of the chin. The thyroid notch can be felt two finger-breadths below the hyoid bone, as a firm V-shaped depression. The thyroid notch is the superior border of the thyroid cartilage which continues inferiorly at a distance of approximately two finger-breadths. The two halves of the thyroid cartilage can be felt extending laterally. The cricoid cartilage is the next rigid structure, palpated immediately below the thyroid cartilage. There is a soft declivity between the thyroid and cricoid cartilages spanning less than one finger-breadth. This is the cricothyroid membrane through which a cricothyrotomy is created. The tracheal rings and overlying thyroid gland are palpable inferior to the cricoid cartilage. The sternal notch lies at the base of the neck (see ▶ Fig. 12.1 and ▶ Fig. 12.2).
The only intervening tissue layers between the skin surface and the cricothyroid membrane are the epidermis, dermis, superficial cervical fascia containing subcutaneous adipose tissue, and the investing and pretracheal layers of the deep cervical fascia. Practically, these tissue layers are quite thin (with the exception of subcutaneous adipose tissue which may be variable). To the naked eye, the layers will appear as a skin, a variable amount of fat, and a veil of fascia overlying the cricothyroid membrane (see ▶ Fig. 12.3). Platysma and strap muscles (sternohyoid, omohyoid, thyrohyoid, and sternothyroid) are typically absent in the midline at the level of the cricoid cartilage (see ▶ Fig. 12.4 and ▶ Fig. 12.5). The innominate artery crosses the lower trachea from left to right and is typically well below the site of cricothyrotomy.
Fig. 12.5 Subfascial structures of neck.
Identification of the cricothyroid membrane by palpation may be difficult or impossible in the setting of obesity, a short and stout neck, neck trauma, neck mass, or prior neck surgery. In such circumstances a large incision may be necessary to successfully perform a cricothyrotomy.
12.3 Indications
Cricothyrotomy is indicated for a patient in respiratory failure who cannot be intubated or ventilated. Alternative procedures include fiber-optic intubation, insertion of a supraglottic airway device, retrograde intubation, needle cricothyrotomy, and tracheostomy. (The approach to a difficult airway is reviewed in detail in Chapter 11, Intubation.) Ultimately, cricothyrotomy is the rescue procedure of choice when such alternative procedures have been attempted without success or when the patient is in extremis. Specific clinical scenarios which may require cricothyrotomy are multifarious and include upper airway obstruction/inflammation, oral/facial trauma, airway hemorrhage, neck trauma/hematoma, oropharyngeal or neck mass, and congenital deformities.
12.4 Contraindications
There are no absolute contraindications to cricothyrotomy but alternative surgical airways are preferred in certain scenarios. When there is suspected transection of the larynx or upper trachea, a tracheostomy should be performed to establish the airway below the level of injury. In patients under the age of 12 cricothyrotomy carries an increased risk of permanent laryngeal injury.1 As such, needle cricothyrotomy or tracheostomy is usually performed in the pediatric population.
12.5 Equipment
If required, cricothyrotomy can be performed using only a scalpel and an endotracheal tube, tracheostomy tube, or other canula. In general, the procedure should not be delayed to gather additional supplies. When time and availability permit, the following equipment may be helpful:
•Cap, mask, gown, sterile gloves, perforated sterile drape
•Marking pen
•Gauze
•Chlorhexidine gluconate or betadine skin prep
•Light source
•Suction
•#15 or #10 blade scalpel
•Mosquito clamp or tracheal spreader
•Electrocautery
•Self-retaining retractor
•Tracheal hook
•Bougie
•6.0 endotracheal tube (flexible tipped tube preferred) or 6.0 tracheostomy tube
•Stylet
•10 cc syringe
•Ambu bag
•Oxygen source
•End tidal CO2 detector
•2–0 silk sutures
12.6 Technique
12.6.1 Preparation
•A team effort should be made with all available personnel to gather the aforementioned equipment.
•In addition to the primary operator, an assistant familiar with performing cricothyrotomy can be extremely helpful.
12.6.2 Medications
•An attempt should be made to ventilate the patient and deliver 100% oxygen. Oxygen content should be turned down if it becomes necessary to utilize electrocautery in or around the airway.
•Antibiotics are not necessary.
•Lidocaine with epinephrine can be used for local anesthesia if time permits.
12.6.3 Positioning/Equipment Set-up
•Position the patient supine with a shoulder roll placed horizontally behind the scapula and the neck extended (unless contraindicated).
•If there is time, mark out the thyroid notch, cricoid cartilage, sternal notch, and a 5 cm vertical incision in the midline centered over the cricothyroid membrane.
•Train any available lights on the surgical site.
•Don a sterile gown, cap, facemask, and gloves.
•Apply sterile prep and drape the neck.
•Inject local anesthetic at the incision site in an awake patient.
•A right-handed physician should stand on the patient’s right side to perform the procedure and a left-handed physician should stand on the left.
12.6.4 Procedure
•Pinch the thyroid cartilage with the nondominant hand to assist with orientation and stabilize the larynx.
•Make a generous midline vertical incision centered over the cricothyroid membrane. This should be extended if needed.
•Divide the subcutaneous tissue and superficial fascia. (In reality, the incision can often be made straight down to the cricothyroid membrane.)
•Place a self-retaining retractor into the wound if one is available.
•Palpate the cricoid cartilage.
•Spread the deep cervical fascia with the mosquito clamp, exposing the cricothyroid membrane.
•Incise the cricothyroid membrane horizontally with the knife.
•Advance the mosquito clamp into the airway. (A tracheal hook can also be used at this point.)
•Spread the clamp to widen the opening in the cricothyroid membrane. (If no clamp is available, the blunt end of the scalpel can be inserted into the airway and twisted to accomplish the same purpose.)
•Once the cricothyrotomy has been performed the airway should be secured using an available tracheostomy or endotracheal tube. A bougie can be used to maintain access to the airway if readily available.
•Remove the stylet if one is used.
•Inflate the endotracheal or tracheostomy tube cuff.
•Connect the endotracheal or tracheostomy tube to an ambu bag or ventilator.
•Confirm appropriate return of end-tidal CO2.
•An assistant should auscultate to confirm bilateral breath sounds.
•Assess adequacy of oxygen delivery.
•Achieve hemostasis.
•If an endotracheal tube is used, it can be secured with two “Roman Sandal” 2–0 silk sutures and tape. A tracheostomy tube can be directly sutured to the neck with 2–0 silk sutures.
•Dress the wound with gauze.
•Obtain a chest X-ray to confirm appropriate placement and to rule out pneumothorax.
See ▶ Fig. 12.6, ▶ Fig. 12.7, ▶ Fig. 12.8, ▶ Fig. 12.9, and ▶ Fig. 12.10.
Fig. 12.6 Skin incision.
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