Indications for surgical airway access vary from the elective through to impending airway compromise, and finally to the true emergency “cannot intubate, cannot oxygenate” scenario. This chapter will deal primarily with techniques of surgical airway (cricothyrotomy) access that the practitioner can use to deal with the difficult airway that presents either in the form of impending airway compromise or the life-threatening emergency.

Why Cricothyrotomy and Not Tracheotomy?

The higher complication rate of emergency tracheotomy, compared to cricothyrotomy,² results from the fact that the trachea is situated deeper in the neck, the posterior tracheal wall lacks the protection of a circumferential cricoid cartilage (increasing the risk of esophageal perforation), there is a greater abundance of adjacent vascular structures, and there is a proximity of the thyroid gland and lung apices. The palpable, often visible, surface landmarks of the thyroid and cricoid cartilages and the ability to accomplish the task faster, with a minimum of equipment, making emergency cricothyrotomy more attractive than tracheotomy, for the surgeon and non-surgeon alike.³

As a consequence, all of the techniques to be discussed with the exception of open and percutaneous dilational tracheotomy (see Chapters 15 and 33) and possibly needle insufflation in children will involve access to the airway through the cricothyroid membrane (CTM).

What Is the History of Cricothyrotomy?

Surgical access to the airway has its origins in ancient times but it was the pandemic of “morbus strangulatorius” in Europe at the beginning of the 19th century that began its modern evolution. The French surgeon, Pierre Bretonneau, first attempted to relieve the laryngeal obstruction of this infectious laryngo-tracheal-bronchitis by tracheotomy in 1818, finally meeting with success in 1825.⁴ His paper, published in 1826, gave the disease entity the name diphtheria,⁵ from the Greek “diphthera” meaning leather. This was in recognition of the thick, leathery, blue white upper respiratory tract membranes characteristic of the disease.⁶ In the 20 years that followed, Armand Trousseau, Joseph Récamier, and M. P. Guersant honed the technical aspects of “bronchotomy”⁷—laryngotomy and tracheotomy—and by 1851 Trousseau published his experience in 222 cases, 127 of whom survived.⁸

In the United States, Chevalier Jackson⁹ published further refinements to the technique in 1909. More than a decade later (1921), he published a paper attributing the devastating complication of subglottic stenosis (SGS) to “high” tracheotomy, concluding that the only acceptable point of access to the airway was below the first tracheal ring and that “high” tracheotomy should be abandoned.¹⁰ Jackson was a figure of immense authority¹¹ and it is not surprising that “high” tracheotomy, or cricothyrotomy, was relegated to almost total obscurity for close to five decades.

Brantigan and Grow³ renewed interest in the approach following publication of their 1976 paper. The impetus for the study came from anecdotal experience during the early days of cardiac surgery. Grow, a student of Chevalier Jackson, looked to cricothyrotomy as a way to avoid contamination of median sternotomy wounds by pathogens tracking down the shared mediastinal tissue planes from open tracheotomy sites. He began performing cricothyrotomy, initially in emergency situations, and later electively when it was evident to him that SGS did not appear to be a problem.

Grow and Brantigan reported their experience in 655 cricothyrotomies performed over an 8-year period. Duration of intubation ranged from 1 to less than 40 days, with an average of 7 days. Their results showed minimal complications and no cases of SGS. Subsequently, several authors,^12–14 including a recent prospective study,¹⁵ reported similar findings in patients not previously subjected to prolonged endotracheal intubation, or suffering from any acute laryngeal pathology.

The discrepancy between the observations of Jackson in the 1920s and the modern authors results from several factors that reflect the two eras, separated by over half a century. Most of the indications for a surgical airway in Jackson’s era were inflammatory in nature; cricothyrotomy in the presence of inflammation is now well recognized to predispose to SGS. In addition, “high” tracheotomy was a much more complex procedure than the modern cricothyrotomy, involving division of the cricoid or thyroid cartilages. The lack of antibiotics, and the primitive design of the tracheostomy tubes available in the 1920s, undoubtedly compounded the situation.¹⁶

As cricothyrotomy is more advantageous for its speed, safety, and simplicity,¹⁷ access through the CTM is the technique of choice in emergency surgical airway management.

Talving et al.¹⁸ reviewed 30 years of literature to determine the rate of development of SGS following emergency cricothyrotomy, with a subset analysis of trauma patients, making up approximately one-third of the total number. The overall rate of SGS was identified in 2.2% of survivors and 1.1% of trauma patients. Interestingly, the rate of development of SGS in the emergency airway is comparable to the rate of SGS from endotracheal intubation, ranging from 0.9% to 8.3% in the literature. Although a well-designed randomized, prospective study is warranted, it currently appears that in the absence of an inflammatory cause of airway obstruction, the development of SGS by emergency cricothyrotomy poses little change in risk to that of routine, daily endotracheal intubation. Although there is increasing evidence to support a change in current practice, most practitioners would prefer to convert a cricothyrotomy to a tracheotomy within 24 hours to avoid the devastating complication of SGS.

What Anatomy Do I Have to Know to Perform These Procedures?

Access to the airway through the CTM requires a practical knowledge of the anatomy of the larynx, particularly the surface landmarks, as well as the important adjacent structures in the neck.

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). Between the inferior margin of the thyroid and cricoid cartilages is the CTM. The size of the membrane in adults is 22 to 33 mm wide and 9 to 10 mm high.¹⁹ Should landmarks be difficult to palpate, the level of the CTM can be estimated by the finger stacking technique (or four-finger technique)²⁰: 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 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 with two neck creases inferior to the mentum, the second skin crease was about 2.0 mm (median distance) above the cricoid cartilage (Figure 14–2).²¹

The vocal cords are attached to the internal, anterior surface of the thyroid cartilage approximately 1 cm above its inferior border.²² Care should be exercised in placing retraction instruments superior to the cricothyroid incision to minimize trauma to the vocal cords and body of the thyroid cartilage in the anterior midline. The only vascular structure of note in the vicinity of the CTM is the superior thyroid artery, which, in 54% of people, courses along its lateral border.²³ The left and right cricothyroid arteries, branches of their respective superior thyroid arteries, course medially and traverse the upper half of the CTM,²³ anastomosing in the midline. Injury to these vessels can be avoided by entering the CTM in its inferior half.

Other important anatomical structures include the hyoid bone and the thyroid gland with its central isthmus and possible presence of an attached pyramidal lobe. The airway itself is suspended by the hyoid bone lying superior to the thyroid cartilage. Identifying the hyoid bone is important to avoid mistaking the thyrohyoid space for the CTM. In patients with poorly palpable surface anatomy, the location of the hyoid bone can be estimated by extending a line from the mentum posteriorly, half the distance between the mentum and the angle of the mandible,²⁴ and distinguishing this underlying structure from the lower lying thyroid and cricoid cartilages. Identifying all the laryngeal structures, whether from top down or down up, is crucial prior to making a surgical incision.

The thyroid gland has a pyramidal lobe in up to 40% of patients.²⁵ The pyramidal lobe is highly vascular and has a propensity to come off the left side of the thyroid isthmus. Extension superiorly beyond the thyroid cartilage is often notable as a fibrous band which is a remnant of the thyroglossal duct. Extension beyond the thyroid cartilage as high as the hyoid bone is very rare^26,27 and poses a small additional bleeding risk due to injury during cricothyrotomy.

How Can I Predict Whether Access Through the CTM Will be Difficult?

Although there is no formal evidence, it is intuitive that anything interfering with either physical access to the larynx, or the ability to appreciate the landmarks of the larynx, will make CTM puncture difficult. This includes factors such as previous surgery, fixed cervical spine flexion deformity, hematoma, obesity, radiation to the neck, laryngotracheal malignancy, or tumor. SHORT (Surgery/Spine, Hematoma, Obesity, Radiation, and Tumor) is a useful mnemonic to remind practitioners of the factors that may be associated with a difficult surgical airway (see section “Difficult Cricothyrotomy: SHORT” in Chapter 1). Pediatric patients also pose great difficulty as the laryngeal structures and spaces are small and difficult to palpate and won’t mature until approximately 12 years of age.

Can the CTM Anatomical Landmark be Better Defined?

Ultrasound-guided identification of the CTM should not be used in a “can’t intubate, can’t oxygenate” emergency situation. However, it can be very useful in accurately identify CTM puncture site prior to induction of an elective or semi-elective patient suspected of having a difficult airway. In a recent review article, Kristensen²⁸ showed that the CTM can be accurately, reliably, and expeditiously identified by bedside ultrasound (Figure 14–3). Studies have shown that practitioners accurately identified the CTM puncture site by palpation in only 10% to 30% of attempts.²⁹ The accuracy in CTM identification was even lower in obese individuals, especially notable in the obese female.^30,31 Prasad et al.³² showed that there is good correlation in identification of airway structures and dimension measurements between ultrasound and CT modalities. Thus in semi-elective cases with suspected or known difficult airway, especially in subjects with difficult CTM identification by palpation, a rapid bedside ultrasound marking of CTM can be quite useful and potentially life-saving.

What Do I Need to Do to Get Ready?

The following are common to all techniques of surgical access by way of the CTM.

1. 
   

   Antisepsis and local anesthetic infiltration:

   
   

   If time permits, every effort should be made to use aseptic technique and infiltrate the proposed surgical site with local anesthetic.

   
   
2. 
   

   Positioning the patient:

   
   

   The patient is ideally placed in the supine sniffing position, ensuring sufficient ramping of the patient so that their earlobes are at or above the level of the sternum, and then extending the head to best expose the surface landmarks of the larynx. In an emergency situation, particularly in the setting of severe upper airway obstruction, it may be necessary to position the patient semi-recumbent, or fully erect.

   
   
3. 
   

   Immobilization of the larynx and identification of the CTM:

Immobilization of the larynx and identification of the CTM is most effectively accomplished by the right-handed practitioner standing on the right side of the patient. The left (nondominant) hand is used to stabilize the larynx by grasping the body of the thyroid cartilage between the thumb and middle finger leaving the index finger free to palpate the cartilaginous structures (Figure 14–4).

If the thyroid notch is palpable, the index finger is moved caudad along the thyroid cartilage, in the midline, until the fingertip dips off its inferior aspect onto the CTM, bounded by the cricoid arch inferiorly. If the landmarks are not palpable, then identification of surface landmarks (“Launcelott creases”), suprasternal finger stacking, or ultrasound-guidance can be used to rapidly guide the airway practitioner to the CTM, as described above.

For transtracheal catheter and Seldinger techniques, some right-handed practitioners will choose to stand over the right shoulder or at the head of the patient, immobilizing the larynx and identifying the CTM, as described above. Others will choose to stand on the left side of the patient for these techniques, immobilizing the larynx and identifying the CTM with the left hand from below. This permits the practitioner to use the right hand to pass implements through the CTM in a caudad direction and in a more dextrous fashion. Primary immobilization of the larynx by the left hand, from below, also minimizes trauma to the thyroid cartilage by promoting retraction of the cricoid ring inferiorly, rather than superior retraction on the thyroid cartilage.

Four methods of surgical access to the airway through the CTM are outlined:

1. 
   

   Open cricothyrotomy

   
   
2. 
   

   Seldinger cricothyrotomy

   
   
3. 
   

   Scalpel bougie cricothyrotomy

   
   
4. 
   

   Transtracheal catheter ventilation

Can You Walk Me Through Each Method…Step by Step?

1. Open cricothyrotomy

Equipment:

The instruments required are: a scalpel with a #11 blade; a tracheal hook; Armand Trousseau dilator; and a 5.0-mm ID cuffed endotracheal tube (ETT), or a small, cuffed tracheotomy tube (Figure 14–5).

Technique:

It should be clearly appreciated by the practitioner that the technique of emergency cricothyrotomy is a sensorially rich procedure. Primarily a tactile technique rather than a visual one, when entering the CTM space an auditory exhaled “woosh” of air, blood, and possibly pulmonary edema will be seen and heard. Landmarks must be palpated from the moment the skin incision is made, as you can no longer rely on your eyes alone once the blood covers the surgical site. Thus mental imagery is a useful skill and should be practiced to promote a positive outcome. With the patient positioned and landmarks identified, the following are steps to a successful standard surgical cricothyrotomy technique:

1. 
   

   A 4.0 cm vertical, midline skin incision (Figure 14–6);

   
   
2. 
   

   A transverse incision of the CTM at the superior border of the cricoid cartilage;

   
   
3. 
   

   Retraction with a tracheal hook (Figure 14–7). Either superiorly, with potential trauma to the vocal cords or thyroid cartilage, or inferiorly, with less risk and perhaps better exposure due to a higher degree of mobility of the cricoid than the thyroid cartilage;

   
   
4. 
   

   Insertion of the Trousseau dilator (Figure 14–8);

   
   
5. 
   

   Caudal placement of a 5.0-mm ID cuffed ETT, or a small, cuffed tracheotomy tube (Figure 14–9);

   
   
6. 
   

   Inflation of the cuff, ensuring the proper position and removal of the hook and dilator.

Prior to securing the tube, it is important to confirm proper placement by ETCO2 and/or by auscultation. A Chest X-ray should be obtained, as soon as conveniently possible, to determine proper tube position and to rule out any parenchymal lung injury or pneumothorax. Current recommendations view a cricothyrotomy as a temporizing, life-saving measure. The patient should undergo conversion to a traditional tracheotomy once stabilized.

2. Seldinger cricothyrotomy technique