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.

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.