Chapter 6 Surgical Airway: Cricothyroidotomy

This chapter will discuss the indications for a surgical airway, or cricothyroidotomy. The relevant anatomy required to successfully and safely perform the technique will be reviewed. The positioning of the patient, the equipment needed, and the steps for a classically performed cricothyroidotomy will be presented in a detailed, stepwise fashion. Finally, the pitfalls associated with this procedure will be briefly discussed.

Learning Objectives

By the end of the ASSET course, participants should be able to do the following:

1. Describe the indication for a surgical airway.
2. Describe the anatomical features and landmarks that will enable success.
3. List the minimal equipment needed to perform an emergency cricothyroidotomy as well as common adjuncts.
4. Correctly demonstrate the steps required for a cricothyroidotomy.
5. Understand the potential pitfalls of this procedure.

General Considerations

• Cricothyroidotomy is an emergent procedure and, although rarely performed, is a critical lifesaving skill.
• Rates of cricothyroidotomy have decreased in recent years, attributable to adoption of advanced video laryngoscopy, improved noninvasive airway rescue techniques, and the presence of adequately trained airway specialists.
• Given the increasing rarity of this procedure, it is imperative that all clinicians be well versed in the technique and frequently practice for the occasional case in which cricothyroidotomy will be required.
• Cricothyroidotomy is indicated when an emergency airway is required and orotracheal or nasotracheal intubation is either unsuccessful or contraindicated.
• Conditions associated with the need for cricothyroidotomy include massive oral and nasopharyngeal hemorrhage, profound emesis in the airway, trismus, obstructing lesions (e.g., tumor, polyp, laryngeal edema, infection, Ludwig’s angina), and a broad range of traumatic and congenital deformities, any of which may prevent successful orotracheal or nasotracheal intubation.
• There are no absolute contraindications to emergency cricothyroidotomy in adults.
• Relative contraindications include a possible or known transection of the trachea, laryngeal fracture, or laryngeal-tracheal disruption. In such cases, tracheostomy or stabilization of the distal tracheal segment followed by direct intubation would likely be the preferred approach.
• The age at which one can safely perform a cricothyroidotomy on a child is not well established, and recommendations vary from five to 12 years old, with the size of the child and presence of palpable landmarks taking precedence over chronologic age.
• If it is clear that a surgical airway is needed, it should be done without delay to avoid hemodynamic collapse, cardiac arrest, and cerebral anoxia due to untreated hypoxemic respiratory failure. Cricothyroidotomy provides the fastest and safest route and requires only basic equipment.
• Cricothyroidotomy is always accompanied by bleeding, and entry into the airway will result in wide dispersal of blood and airway secretions. As such, it is imperative that all members of the team have adequate personal protective equipment, including face and eye protection.

Anatomy and Anatomical Considerations

• Proper performance of a cricothyroidotomy depends on an understanding of the relevant anatomy and the ability to identify the cricothyroid membrane (CTM).
• The CTM is the logical choice for an emergent airway: it is the part of the airway that is closest to the skin, and there are no critical structures between it and the skin.
• The boundaries of the CTM are the thyroid cartilage superiorly, the cricoid cartilage inferiorly, and the cricothyroid muscles laterally on both sides (Figure 1).
• The thyroid cartilage (also known as the “Adam’s apple”) is usually the most reliable landmark, and the laryngeal prominence at the superior border has a V-shaped notch that can be used to orient the anatomy.
• With the patient supine, the CTM is generally 4 fingerbreadths above the sternal notch.
• Identification of the CTM is not always straightforward. Obesity compounds the problem.
• Given the challenges of identifying the CTM, it is preferable to make the skin incision in a vertical (as opposed to horizontal) fashion, as this enables extension either superiorly or inferiorly if the level of the CTM is misidentified. Repeated palpation of the landmarks is essential.
• The cricothyroid arteries are branches of the superior thyroid arteries and course along both sides of the CTM. They anastomose in the midline, just below the thyroid cartilage. Therefore, the CTM should be incised in its inferior third if possible, although this may be difficult to do in emergent setting.
• While there is significant variation in the size of the CTM, the average dimensions are roughly 8–12 mm vertically (from bottom of thyroid cartilage to top of cricoid cartilage) by 20–30 mm horizontally. This gap between the cricothyroid muscles is adequate for insertion of a tube into the trachea.
• The mean internal diameter of the airway at the level of the CTM is roughly 12 mm in women and 15 mm in men. This should be kept in mind when making the incision so as not to injure the back wall, as well as when considering the size of the tube to be used.
• The dimensions of the CTM and the diameter of the airway have a bearing on the size of tube used. It is recommended that a tube of no more than 9–10 mm outer diameter (which corresponds to a 7 mm internal diameter) be used. A good rule of thumb is to choose a tube that is 1 mm smaller than would be used for orotracheal intubation.
• The preferred tube for emergency airways is a number 6 or 6.5 endotracheal tube.
• If a Shiley™ tracheostomy tube is used, it should not exceed a size 4 (9.4 mm outer diameter).

Technique for Cricothyroidotomy

• Several variations of technique for performing a surgical cricothyroidotomy are described. The classical technique shown in this manual was chosen because of the need for minimal equipment, the ability to extend if the anatomy is unclear, and the rapidity with which it can be performed once mastered.
• All members of the team should use standard precautions to protect against blood and body fluid exposure.
• The equipment required to perform a cricothyroidotomy (Figure 2) is minimal, and the entire procedure can be done with just a scalpel, a tube, and a syringe. Common equipment adjuncts include a tracheal hook, a Trousseau dilator or spreader, a Kelly clamp, and a bougie (tracheal tube introducer).
• The patient should be placed in a supine position.
• Unless there is concern for cervical spine injury, extend the patient’s neck to help identify the anatomical landmarks.
• If the patient is being ventilated, once the incision is made in the airway, the airway bag mask ventilations should be discontinued, as this can insufflate the soft tissues of the neck and expel blood into the face of the operator.
• If time permits, the skin of the anterior neck is prepped and the relevant landmarks are marked (Figure 3).

• If the patient is conscious, time permitting, consider using local anesthesia in the skin, subcutaneous tissues, and CTM.
• The operator should stand on the side of the patient corresponding to the operator’s dominant hand (if right-handed, stand on patient’s right side).
• The thyroid cartilage is grasped with the nondominant hand using the thumb and middle finger to stabilize the thyroid cartilage, and the index finger is used to palpate the CTM (Figures 3 and 4). The larynx should be stabilized in this manner throughout the procedure to preserve the anatomical relationships. At this point, it is advisable to not let go with the nondominant hand.
• A vertical incision (3–5 cm in length) is made through the skin and subcutaneous tissues overlying the CTM (Figure 5).
• The index finger is then placed into the wound to palpate and confirm the location of the CTM (Figure 6).

• A 1 cm horizontal incision is made in the CTM (Figure 7).
• The incision through the CTM should be made with care in the lower third of the membrane to avoid the arteries, aimed in a caudad direction to avoid the vocal cords, and limiting the depth of the scalpel to avoid injury to the back wall.
• The scalpel handle can be used to dilate the incision by flipping the scalpel handle 180° and placing the apex of the handle into the wound and rotating it (Figure 8).
• Alternatively, a Trousseau dilator or Kelly clamp can be used to enlarge the incision.
• The selected tube can now be inserted either without (Figure 9) or with (Figure 10) the assistance of a tracheal hook placed under the thyroid cartilage and retracted towards the patient’s head.
• If a dilator or tracheal hook is used, care must be taken when removing the implement to prevent damage to the balloon or accidental dislodgement of the tube.

• Once the tracheostomy tube has been placed into the airway, the obturator is removed and replaced by the inner cannula.
• If a tracheostomy tube is not available, an endotracheal tube can be used, taking care not to insert it too far (which can create a right main-stem intubation). The endotracheal tube is advanced until the balloon passes distal to the CTM.
• The cuff of the tube should then be inflated with air from a 10 cc syringe (Figure 11). The balloon is inflated until the airway is fully occluded. Take care not to overinflate, as this risks pressure-related injury to the tracheal mucosa.
• The tracheal tube is connected to the mechanical ventilator or bag-valve device. Presence of end tidal CO₂ should be confirmed by colorimetric device or wave capnography, and bilateral breath sounds should be confirmed by auscultation. After confirming that the tube is properly positioned in the trachea, the tube is secured with circumferential ties around the neck (Figure 12).
• The technique described above is by no means the only way of performing a surgical cricothyroidotomy, but it represents a standardized, consensus-driven approach that requires minimal equipment and can be done rapidly and with minimal complications by appropriately trained individuals.

Pitfalls and Complications

• Cricothyroidotomy is a lifesaving procedure performed infrequently, in the setting of a patient likely to die unless the procedure is rapidly and correctly performed. As such, there are a number of potential early complications associated with this procedure, as follows:
  • Bleeding/hematoma
  • Incorrect placement and creation of a false passage in the neck tissues
  • Subcutaneous emphysema
  • Posterior tracheal wall perforation
  • Esophageal or mediastinal perforation
  • Thyroid injury and bleeding
  • Vocal cord injury
  • Laryngeal injury
  • Aspiration
  • Airway obstruction
  • Pneumothorax
  • Tube migration or dislodgement
  • Right main-stem intubation if an endotracheal tube is chosen and inserted too deeply
• A number of late complications are also associated with this procedure, including the following:
  • Dysphonia
  • Infection
  • Glottic or subglottic stenosis
  • Laryngeal stenosis
  • Tracheoesophageal fistula
  • Tracheomalacia