The following clinical scenario highlights the importance of front-of-neck access (FONA) in perioperative anesthesia patient care:
A patient presented to the emergency department with significant stridor secondary to a neck mass extending just below his mandible. His past medical history included atrial fibrillation for which he was taking coumadin. Imaging demonstrated that the mass was a neck hematoma secondary to an overdose of coumadin with an INR >6. Due to a high risk of excessive bleeding that resulted in a difficult tracheotomy and severe hypoxemia, the patient underwent an awake flexible bronchoscopic intubation. A double set-up with a FONA was prepared and the neck landmarks for localization of the cricothyroid membrane (CTM) were identified using both palpation and ultrasonography. However, during the bronchoscopic intubation attempt, the patient experienced complete airway obstruction and oxygen desaturation. Without delay, the anesthesia practitioner performed an emergency FONA by accessing the trachea through the CTM using a size 10 scalpel blade, inserting a bougie, followed by a size 6.0 internal diameter endotracheal tube (ETT). Successful cricothyrotomy was confirmed with positive end-tidal CO2, bilateral chest rises, and improved oxygen saturation to 96%. The patient was then transferred to the intensive care unit.
What Anatomy Do I Have to Know to Perform a Front-of-Neck Access?
Access to the airway through the CTM requires a practical knowledge of the anatomy of the larynx, particularly the surface landmarks, and the important adjacent structures in the neck (also see Chapter 3).
In most adult males, the thyroid notch (“Adam’s apple”) is a prominent feature, which identifies the superior aspect of the thyroid cartilage. With the neck extended, palpation inferiorly from this point will often allow the practitioner to identify the inferior margin of the thyroid cartilage and the ringed-shaped cricoid cartilage below (Figure 14.1).
Anatomy of the larynx and trachea: (A) the thyroid cartilage; (B) the cricothyroid membrane; and (C) the cricoid cartilage.
Between the inferior margin of the thyroid and cricoid cartilage is the CTM. The size of the membrane in adults is 22 to 33 mm wide and 9 to 10 mm high.1 Should landmarks be difficult to palpate, the level of the CTM can be estimated by the finger stacking technique (or four-finger technique)2: with the head and neck in neutral position, the fifth finger is placed in the suprasternal notch; with all fingers in juxtaposition, the location of the index finger will approximate the level of the CTM. In addition, skin creases (“Launcelott Creases”) in the anterior neck may also represent a useful visual landmark for estimating the level of the CTM. The study conducted at our institution demonstrated that with the head in the neutral position, in patients ...