Contemporary emergency department studies using RSI demonstrate high success rates (97% to 99%) and an infrequent need for surgical airway rescue (0.5% to 2.0%) even though the unselected nature of the patients and the large percentage with trauma result in a high proportion of DAs compared with those seen in elective surgery.¹^–⁵ Despite increasing familiarity with alternative airway rescue devices (e.g., flexible and semirigid fiberoptic bronchoscopy, video laryngoscopy, retroglottic airways, supraglottic airways, retrograde intubation, lighted stylet) that further reduce the need for cricothyrotomy, the surgical airway remains the final pathway on all failed airway algorithms.⁶ Therein lies the dilemma. As clinicians embrace new technologies and devices that make the need for surgical airway management increasingly rare, acquisition and maintenance of the skills necessary to perform surgical airway management, which in some cases is the only method capable of sustaining a patient’s life, become increasingly elusive.

2 Surgical Airway Management Is Often Performed in Unstable Patients

Surgical airway management is infrequently, if ever, performed in stable patients and is often needed in a “cannot-intubate, cannot-ventilate” (CICV) situation, when failure to perform the technique properly and in a timely fashion may prove disastrous. The patient in need of emergency cricothyrotomy is typically one who has a significantly distorted airway anatomy or who has been subjected to multiple failed intubation attempts, or both. The operator is required to establish an airway in the presence of potentially overwhelming difficulty and with very little time.

3 If a Surgical Approach Fails, Few, If Any, Options Remain

Most would consider surgical cricothyrotomy to be the ultimate consideration among a series of airway management options. In addition, a failed surgical cricothyrotomy may result in bleeding, loss of airway integrity, or further airway distortion, making the success of subsequent rescue attempts highly unlikely.

In sum, emergency cricothyrotomy is a rarely performed procedure, done under duress by clinicians who may have limited experience, in patients in whom it is difficult to perform and who are likely to die if it fails. These challenges speak powerfully to those involved in airway management, counseling them to invest the time required to master this crucial technique. Fortunately, although it has been unfairly cloaked in mystique and represented as dramatic and difficult, cricothyrotomy is a relatively straightforward procedure that can be accomplished with a high success rate and a low rate of complications by providers with adequate but not extensive training. This training can be achieved by using various animal models (not whole animals) and through medical simulation.

B Historical Perspective

The surgical airway as a life-saving procedure has been appreciated for thousands of years. The first depictions of surgical tracheostomy were found on Egyptian tablets dating from 3600 BC.⁷ In the second century AD, Galen suggested tracheostomy, utilizing a vertical incision, as an emergency treatment for airway obstruction.⁸^–¹⁰ Vesalius later published the first detailed descriptions of tracheostomy in the 16th century, using a reed to ventilate the lungs. Ironically, his alleged resuscitation of a Spanish nobleman through tracheostomy and ventilation led to condemnation by the Spanish Inquisition and his ultimate death.¹¹ The first record of a successful tracheostomy performed in the United States was in 1852; the patient later died of airway stenosis, a common complication at that time. A paper from 1886 described a mortality rate of 50% for tracheostomy and a high incidence of stenosis, which accounted for many of the deaths.¹²

Chevalier Jackson published a landmark paper on tracheostomy in 1909, which enumerated principles still relevant today.¹³ He described a surgical mortality rate of only 3%, which he attributed to several factors: optimal airway control before surgery, use of local anesthesia rather than sedation, use of a well-designed tube, and meticulous surgical and postoperative care. Jackson achieved international recognition; however, so did his condemnation of “high tracheostomy” as the cause of subglottic stenosis. The high tracheostomy he referred to was a cricothyrotomy, which at that time involved division of the cricoid or thyroid cartilage. Modern cricothyrotomy involves incision of the CTM only. In 1921, Jackson published a study of 200 patients referred to him for postcricothyrotomy stenosis. Aside from the obvious referral bias, the indication for a surgical airway at that time was primarily inflammatory lesions of the upper airway, which probably accounted for the high incidence of subglottic stenosis.¹⁴

Although in retrospect it was the technique and the underlying condition that were largely responsible for the high rate of stenosis, fear of this complication condemned the technique of cricothyrotomy for over half a century. In the interest of developing a technique that was safer and quicker than Jackson’s open dissection, Toye and Weinstein described the first percutaneous tracheostomy in 1969.¹⁵ However, cricothyrotomy was not widely reconsidered as a surgical airway option until 1976, when Brantigan and Grow published the results of cricothyrotomy for long-term airway management in 655 patients.¹⁶ In their series, the rate of stenosis was 0.01%, no major complications were described, and the procedure was found to be faster, simpler, and less likely to cause bleeding than tracheostomy. Subsequent studies have supported their conclusion that cricothyrotomy is a safe and effective surgical airway procedure and should be the preferred technique when emergent surgical airway control is needed.^7,^17,¹⁸ Contemporary case series have demonstrated that cricothyrotomy can be performed with a high success rate and a reasonably low complication rate by hospital-based physicians and other clinicians (i.e., nurses, paramedics) providing prehospital care.^13,¹⁹^–²⁵

C Definitions of the Surgical Airway

The definition of surgical airway can be so broad as to comprise all forms of airway management that require the creation of a new opening into the airway. Cricothyrotomy is the establishment of a surgical opening in the airway through the CTM and placement of a cuffed tracheostomy tube or ETT. Cricothyrotomy has also been referred to as cricothyroidotomy, cricothyroidostomy, cricothyrostomy, laryngostomy, or laryngotomy; however, cricothyrotomy is presently the preferred term. Tracheostomy differs from cricothyrotomy in the anatomic location of entry into the airway. Tracheostomy is the establishment of a surgical opening in the airway at any level including at or caudal to the first tracheal ring.

Surgical airways may be further subclassified according to the technique used: (1) surgical (sometimes referred to as “open” or “full open” or “full surgical”); (2) percutaneous (more precisely described by the actual technique, such as Seldinger); (3) dilational (a distinct percutaneous approach); and (4) transtracheal catheter.

The terms surgical cricothyrotomy and surgical tracheostomy refer to the use of a scalpel and other surgical instruments to create an opening in the airway.^26,²⁷ This technique allows the creation of a definitive, protected airway by the insertion of a cuffed tracheostomy tube with an internal diameter sufficient for ventilation, oxygenation, and suctioning.

The percutaneous dilational technique utilizes a kit or device that is intended to establish a surgical airway without requiring a formal surgical cricothyrotomy (see Chapter 30 for a detailed discussion). Following a small skin incision, the airway is accessed by a small needle through which a flexible guidewire is passed using the Seldinger technique. The airway device is then introduced over a dilator and passed over the guidewire and into the airway in a manner analogous to that of central line placement. An alternative percutaneous technique has been used that relies on placement of an airway device using a direct puncture into the airway; an example is the Nu-Trake Adult Emergency Cricothyroidotomy Device (Smiths Medical, Keene, NH). A large-bore metal needle or a sharp trocar within the catheter is used to puncture the airway directly, without the use of a guidewire. Direct puncture devices are more hazardous and have fallen out of favor because of a higher incidence of complications and a lower success rate compared with other percutaneous techniques.²⁸^–³²

Transtracheal catheter ventilation, considered the least invasive surgical technique, involves the direct placement of a moderate-bore catheter through the CTM.³³ The small caliber of these devices does not allow adequate oxygenation without attachment to a high-pressure oxygen source or jet ventilator, except in small children, and does not support adequate ventilatory gas exchange. A 6-F reinforced fluorinated ethylene propylene, kink-resistant emergency transtracheal airway catheter (Cook Critical Care, Bloomington, IN) has been designed as a kink-resistant catheter for this purpose.

D Role of the Surgical Airway

The relative merit of percutaneous dilatational tracheostomy versus open surgical tracheostomy continues to be a subject of debate. Although formal open tracheostomies are primarily performed by surgeons, the percutaneous dilatational tracheostomy is frequently performed by anesthesiologists and other nonsurgical intensivists, particularly in the intensive care setting. This technique was originally described by Toye and Weinstein in 1969, but it did not gain popularity until the results with a modified device were reported by Ciaglia and colleagues in 1985.^12,¹⁵ There have been no clinical studies to date demonstrating the superiority of any one approach over another or of any of these devices over formal surgical cricothyrotomy.

II Anatomy

An understanding of the anatomy of the upper airway and the neck is required for the successful and rapid performance of a surgical airway. Most emergent surgical techniques involve surgical fields that become rapidly obscured by blood and for this reason they are, essentially, “blind” procedures. The identification of anatomic landmarks is critical.

A Bones and Cartilages

The horseshoe-shaped hyoid bone is the most cephalad rigid structure in the anterior neck, palpable approximately one finger breadth cephalad to the laryngeal prominence. It suspends the larynx during phonation and respiration by the thyrohyoid membrane and muscle.

The thyroid cartilage is the largest structure of the larynx and consists of two laminae fused in the midline to form the laryngeal prominence. The angle of this fusion is more acute in males, creating the more distinct prominence known as the Adam’s apple. The separation of the laminae superiorly forms the palpable superior thyroid notch. The laryngeal prominence of the thyroid cartilage represents the most readily and consistently identified landmark in the neck when one is performing a surgical airway. The superior and inferior cornua of the thyroid cartilage are the posterior extensions of the upper and lower edges of the lamina. The thyrohyoid ligament attaches to the superior cornu, and the posterior cricoid cartilage articulates with the inferior cornu.

The cricoid cartilage, the only complete cartilaginous ring in the upper airway, defines the inferior aspect of the larynx (Fig. 31-1). It is shaped like a signet ring, with the wider lamina posterior. Superiorly, the lamina has synovial articulations with the arytenoids and thyroid cartilage. Anteriorly, the cricoid ring is attached to the inferior thyroid cartilage by the CTM.

Figure 31-1 Surface anatomy of the larynx.

(From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

B Cricothyroid Membrane

The CTM is a fibroelastic tissue that covers the cricothyroid space, between the thyroid cartilage and the cricoid ring. It is trapezoidal in shape and in the average adult is 1 cm high and 2 to 3 cm wide. It is located in the midline, approximately 2 to 3 cm below the laryngeal prominence. The vocal cords are located 1 cm above the CTM and therefore are rarely injured during a cricothyrotomy.

Several anatomic characteristics make this membrane an ideal choice for emergency airway access. It is a subcutaneous structure located just beneath the skin, a small amount of subcutaneous fat, and the anterior cervical fascia in most patients. Accordingly, it is easily palpated as a depression inferior to the thyroid cartilage, bounded on its inferior aspect by a hard ridge, the cricoid cartilage. The ligament does not calcify with age. It has no overlying muscles, major vessels, or nerves. It is supported by the anterior cervical fascia, which is not robust at this level.

C Vascular Structures

The major arteries of the neck always lie deep to the pretracheal fascia and should not present a concern when incising the skin over the CTM. The paired superior thyroid arteries arise from the external carotid arteries, superior and lateral to the cricoid cartilage. The anterior branches of these arteries run along the upper thyroid isthmus to anastomose in the midline. The unpaired inferior thyroid artery also anastomoses with the superior thyroid artery at the isthmus. In 10% of the population, the potentially large thyroid ima artery ascends anterior to the trachea to join the anastomoses. A large venous plexus is found over the thyroid isthmus.

The right and left cricothyroid arteries are branches of the right and left superior thyroid arteries, respectively, and in most patients they cross the superior aspect of the CTM to anastomose in the midline.³⁴ Although they are at risk for injury during a cricothyrotomy, they do not appear to be clinically significant. Bleeding is often self-limited and is easily controlled with gauze packing. There is no venous plexus over the CTM.

D Thyroid Gland

The isthmus of the thyroid gland lies anterior to the trachea, generally between the second and third tracheal rings, although it may extend to the first and fourth rings. Its size and location can be variable; however, its average height and thickness are 1.25 cm. A pyramidal lobe of the thyroid gland is present in one third of the population and extends superiorly from the isthmus, over the cricoid membrane and larynx to the left of the midline.

E Anatomic Variations

In infants, the hyoid bone and cricoid cartilage are the most prominent structures in the neck. The laryngeal prominence does not develop until adolescence. The larynx also starts higher in the neck of the child; it descends from the level of the second cervical vertebra at birth to the level of the fifth or sixth in the adult.³⁵ The laryngeal prominence is more acute and therefore more prominent in adult males compared with females. This also results in longer vocal cords and accounts for the deeper voices of males.

The CTM varies in size among adults and can be as small as 5 mm in height. This space may narrow further with contraction of the cricothyroid muscle.³⁶ The CTM in the child is disproportionately smaller in area than that in the adult (Fig. 31-2). In an infant, the width of the membrane constitutes only one fourth of the anterior tracheal diameter, as opposed to three fourths in the adult. Because of this smaller area and the difficulty in identifying landmarks in children, emergency surgical cricothyrotomy is difficult and hazardous in small children and is not recommended in those younger than 10 years of age. In this age group, placement of a needle catheter with percutaneous transtracheal ventilation is the preferred method.

Figure 31-2 Anatomic differences in the pediatric compared with the adult airway: (1) higher, more anterior position for the glottic opening; (2) relatively larger tongue in the infant, which lies between the mouth and glottic opening; (3) relatively larger and more floppy epiglottis in the child; (4) the cricoid ring is the narrowest portion of the pediatric airway (in the adult, the narrowest portion is the vocal cords); (5) different position and size of the cricothyroid membrane (CTM) in the infant; (6) sharper, more difficult angle for nasotracheal intubation; (7) larger relative size of the occiput in the infant. See text for details.

(From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

Identification of landmarks in the obese, edematous, or traumatized neck can be difficult. The CTM usually lies 1.5 finger breadths (using the patient’s fingers) below the laryngeal prominence. Alternatively, its location may be estimated to be three to four finger breadths above the suprasternal notch when the neck is in a neutral position.

There can be significant variation in the arterial and venous pattern in the anterior vessels of the neck, which can result in a major artery’s crossing the midline. This is rarely a problem for cricothyrotomy, because most anomalous vessels are present lower in the neck.

III Surgical Cricothyrotomy

A Indications and Contraindictions

The primary indication for an emergent surgical airway (Box 31-1) is the failure of endotracheal intubation or alternative noninvasive airway techniques in a patient who requires immediate airway control. The American Society of Anesthesiologists (ASA) DA algorithm advocates a surgical airway as the final end point for the unsuccessful arm of the emergency pathway.^37,³⁸ There are a number of other DA algorithms in the literature, as well as numerous modifications of the ASA guidelines; however, all comprehensive pathways include the surgical airway as the technique of choice when others have failed.³⁸^–⁴⁰ Despite the introduction of numerous alternative rescue devices, the most common error in the management of the DA is persistent attempts at laryngoscopy in a failed airway situation.⁴¹^–⁴³ This behavior has been associated with increased morbidity and mortality.⁴¹ Identification of the CICV scenario should result in immediate consideration of surgical airway access. If alternative methods are tried despite inability to oxygenate and ventilate the patient by bag and mask, precious time may be lost in what are ultimately futile attempts, and by the time cricothyrotomy is undertaken and accomplished, delays in achieving airway control and oxygenation will have led to hypoxic brain injury.

In most circumstances, cricothyrotomy is regarded as an emergency rescue technique when other noninvasive rescue techniques, such as the laryngeal mask airway, have failed, are predicted to fail, or are unavailable.¹ There are occasions, however, when a cricothyrotomy is the primary airway of choice. An example is the patient who has such severe facial trauma that nasal or oral approaches to the airway are deemed impossible. There also has been a renewed interest in the role of elective cricothyrotomy in the operative setting. Some cardiothoracic surgeons prefer cricothyrotomy to a tracheostomy in their patients with a median sternotomy, believing that the higher location of the airway wound reduces the potential for contamination of the sternal wound.¹¹ A study described the use of elective cricothyrotomy instead of tracheostomy in the intensive care unit for trauma patients with technically challenging neck anatomy. The procedure was described as simpler with no difference in short- or long-term complications.⁴⁴

Cricothyrotomy is considered safe in trauma patients with unstable cervical spine injuries provided that cervical spine immobilization is maintained.^45,⁴⁶ Although coagulopathy has been described as a relative contraindication, there are reports of successful cricothyrotomy after systemic fibrinolytic therapy for acute myocardial infarction.⁴⁷

Often, the main hurdle to performing cricothyrotomy is simply making the initial decision to forego further attempts at laryngoscopy or with other rescue devices and to proceed with a surgical airway. Noninvasive airway management methods are used so successfully that cricothyrotomy is often viewed as a procedure that will never be required. However, the single-minded pursuit of multiple noninvasive airways with resultant delay in the initiation of a surgical airway can result in hypoxic disaster, particularly if the patient is not able to be oxygenated and ventilated adequately with a bag and mask between attempts.

The decision to proceed to a surgical airway must also take into account some other important variables. The airway provider must appreciate whether the surgical airway will bypass the airway problem anatomically. For example, if the obstructing lesion is infraglottic, performing a cricothyrotomy may be a critical waste of time. The patient’s anatomy and pathology must be considered when weighing the difficulty of performing a cricothyrotomy. Placement of the initial skin incision is based on palpation of the pertinent anatomy. Adiposity, burns, trauma, or infection may make palpation difficult; they do not represent absolute contraindications, but the strategy may need to be adjusted. The operator must also consider the type of invasive technique (i.e., open surgical or percutaneous). This consideration takes into account provider preference based on experience, the patient’s presentation, and equipment availability.

Contraindications for surgical airway management are few and, with one exception, are relative. That one exception is young age. Children have a small, pliable, mobile larynx and cricoid cartilage, making cricothyrotomy extremely difficult. For children younger than 10 years, unless the larynx and cricoid cartilage are teenage or adult sized, percutaneous transtracheal ventilation should be used as the surgical airway management technique of choice. Two other situations have been proposed as absolute contraindications: tracheal transection and laryngeal fracture.⁴⁸ In either situation, tracheostomy has been recommended as the preferred method. Although anatomically and philosophically appealing, this assertion is clinically impractical. First, these injuries may not be readily apparent at the bedside. Second, there may be no other means of securing the airway in a dying patient. Third, expert surgical backup may not be readily available, and tracheostomy is a much more complicated procedure than cricothyrotomy. Therefore, these, too, should be considered relative contraindications; cricothyrotomy should be recognized as carrying significant risk in these situations and used when there is thought to be no other method to secure the airway. Relative contraindications also include preexisting laryngeal or tracheal pathology such as tumor, infections, or abscess in the area in which the procedure will be performed; hematoma or other anatomic destruction of the landmarks that would render the procedure difficult or impossible; coagulopathy; and lack of operator expertise.

The presence of an anatomic barrier in particular should prompt consideration of alternative techniques that might result in a successful airway. However, in cases in which no alternative method of airway management is likely to be successful or timely enough, cricothyrotomy should be performed without hesitation. The same principles apply for both the cricothyrotomy and percutaneous transtracheal ventilation. Percutaneous transtracheal ventilation is the surgical airway method of choice for children younger than 10 years of age. The cricothyrotomes have not been demonstrated to improve success rates or time or to decrease complication rates when compared with surgical cricothyrotomy. As with formal cricothyrotomy, experience, skill, knowledge of anatomy, and adherence to proper technique are essential for success when a cricothyrotome is used. The large size and cutting characteristics of the insertion part of the cricothyrotome are likely to cause more damage in the neck than either an open cricothyrotomy or a Seldinger-based technique.

B Procedure

1 Equipment

Tracheostomy tubes are made in a variety of designs and materials.¹⁵ They may have a single lumen, but many have an inner cannula that can easily be removed to allow routine cleaning and prevention of mucous obstruction. Most tubes also come with a blunt-tipped obturator that is used to facilitate insertion and reduce trauma. The tubes may be rigid or flexible and kink resistant, and they may have variable curves, angles, and sizes, depending on the anatomic needs of the patient. Tracheostomy tubes are secured with twill or with a padded fastener that goes around the neck and attaches to the neck plate of the tube. Tubes may be cuffed or uncuffed. Cuffs should be kept at inflation pressures of 20 to 25 mm Hg, but over the short term, inflation can be judged by palpation of the reservoir balloon.⁴⁹ Underinflation can increase aspiration, whereas high cuff pressures can cause mucosal ischemia and subsequent tracheal stenosis or tissue necrosis.

It is critical that whatever surgical technique is chosen, the instrument and its location are familiar to the airway providers. The kit needs to be easily accessible, compact, and ideally located in a DA cart that is positioned in the room or otherwise readily accessible (Fig. 31-3). The operating room tracheostomy surgical trays are not appropriate for this purpose because of their size and complexity. It is recommended that a custom cricothyrotomy kit be assembled with the components listed in Box 31-2 or that a commercial kit designed for this purpose be utilized. A commercial kit has become available that offers both the Seldinger technique and the necessary instruments for a surgical cricothyrotomy with a cuffed tracheostomy tube all in one system (Fig. 31-4).

Figure 31-3 A simply organized cricothyrotomy tray with tracheal hook, Trousseau dilator, scalpel, and tracheostomy tube.

(Photograph courtesy of R. M. Walls, Boston, MA)

Box 31-2

Recommended Contents of Cricothyrotomy Kit

A. Trousseau dilator

B. Tracheal hook

C. Scalpel with No. 11 blade

D. Cuffed, nonfenestrated No. 4 Shiley tracheostomy tube

E. Several 4 × 4 gauze sponges, 2 small hemostats, surgical drapes

From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.

Figure 31-4 A Melker Universal Cricothyrotomy Set combines capability for a percutaneous, Seldinger-based cricothyrotomy (right side) with a simple instrument set for a full surgical cricothyrotomy (left side). The same cuffed tracheostomy tube is used for either technique, but a blunt introducing cannula is substituted when surgical insertion is desired.

(Photograph courtesy of Cook Critical Care, Bloomington, IN. Copyright by Cook Critical Care.)

2 Landmarks

The CTM is the anatomic site of access in the emergent surgical airway, regardless of the technique used. The CTM is identified by first locating the laryngeal prominence of the thyroid cartilage. This may be easier to appreciate in males because of their more prominent thyroid notch. Approximately 1 to 1.5 patient finger breadths below the laryngeal prominence, the membrane may be palpated in the midline of the anterior neck as a soft depression between the inferior aspect of the thyroid cartilage above and the rigid cricoid ring below. The thyrohyoid space, which lies superior to the laryngeal prominence and inferior to the hyoid bone, should also be identified. This space should be distinguished from the CTM to avoid misplacement of the tracheostomy tube above the vocal cords. In children, the CTM is disproportionately smaller because of a greater overlap of the thyroid cartilage over the cricoid cartilage. For this reason, cricothyrotomy is not recommended in children younger than 10 years of age.

The same anatomic or physiologic abnormalities (i.e., trauma, morbid obesity, congenital anomalies) that precipitated the surgical airway may also hinder easy palpation of landmarks. The location of the CTM can be estimated by placing four fingers on the neck, vertically, with the small finger in the sternal notch. The membrane is approximately located under the index finger, and this can serve as a point at which the initial incision is made. A vertical skin incision is preferred in the emergent situation because of the location of major blood vessels as well as ease in locating the membrane. Palpation through the vertical incision can then confirm the location. Identification may be assisted by using a locator needle attached to a syringe containing saline or lidocaine. Aspiration of air bubbles suggests entry into the airway, but this does not distinguish between the CTM and an intertracheal space.

Although palpation of the CTM is easily performed on most patients, the particular condition creating the airway difficulty may obscure traditional landmarks. The urgency and anxiety associated with a failed airway may further compound this difficulty. Therefore, it is the practice of some anesthesiologists to mark the skin overlying the approximate location of the CTM before the procedure begins if a possible DA is anticipated. Routinely palpating the CTM on patients is also recommended to become familiar with the landmarks.

C Surgical Cricothyrotomy Techniques

1 Traditional Surgical Cricothyrotomy: The “No-Drop” Technique

a Preparation of the Neck

Appropriate antiseptic solution should be applied and sterile technique observed as much as possible. The procedure should not be delayed if time does not allow ideal preparation. Suction, a bag-valve-mask, and oxygen should be immediately available. The tracheostomy tube should be opened and prepared for insertion at this time. There may be circumstances (e.g., conscious patient) in which it is desirable to infiltrate the skin and subcutaneous tissues with 1% lidocaine. The operator may wish to localize the membrane at this time using a 20-G needle. On aspiration of air into syringe, lidocaine can be injected into the airway. The injection precipitates a cough in the patient with intact airway reflexes; however, this serves to disperse the lidocaine and diminish further stimulation in the conscious patient. Caution is advised in patients with potentially unstable cervical spine injuries.

b Landmark Identification

An emergent cricothyrotomy is best thought of as a procedure that is done by touch rather than by visualization. The identification of the external landmarks before initiating the incision and the use of a method to maintain knowledge of the anatomic relationships (see later discussion) are keys to success. The operator should be positioned on the same side of the patient as the operator’s dominant hand (i.e., the hand that will be used to make the incisions); for example, a right-handed operator stands to the patient’s right. After identification of the laryngeal prominence, the superior horns of the thyroid cartilage are firmly grasped between the thumb and long finger of the nondominant hand. This leaves the index finger ideally positioned to localize the CTM and re-identify its location at any time during the procedure by capitalizing on the constancy of the relationship as long as the thyroid cartilage is not released. Therefore, it is critical that control of the larynx with this hand be maintained until the placement of the tracheal hook (Fig. 31-5).

Figure 31-5 A and B, With the superior cornua of the larynx firmly immobilized by the thumb and long finger of the nondominant hand, the index finger is free to palpate and locate the cricothyroid membrane (CTM).

(A adapted from and B from Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

c Vertical Skin Incision

The operator uses the dominant hand to make a generous vertical incision in the midline, with its center over the CTM. The incision should be at least 2 cm in length and may need to be extended in patients with significant obesity or if identification is difficult. The incision should go through subcutaneous tissues down to, but not into, the thyroid and cricoid cartilages (Fig. 31-6).

Figure 31-6 A and B, A vertical skin incision is made down to, but not through, the airway.

(A adapted from and B from Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

d Confirmation of Membrane Location

With the thumb and long finger maintaining control of the thyroid cartilage, the index finger may now be inserted into the incision. Without interposed skin and tissues, it is much easier to appreciate the structures of the anterior neck and to confirm the location of the CTM. The index finger can be left in the wound, resting on the inferior aspect of the anterior larynx, indicating the superior limit of the CTM (Fig. 31-7).

Figure 31-7 A and B, The index finger can now directly palpate and relocate the cricothyroid membrane.

(A adapted from and B from Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

e Horizontal Incision of the Cricothyroid Membrane

The index finger may be withdrawn just prior to incision or left in the wound to serve as a guide. The CTM should be incised horizontally for a distance of 1 to 2 cm (Fig. 31-8). It is recommended that an attempt be made to incise the lower half of the membrane to avoid the superiorly placed cricothyroid artery and vein. This can be difficult to achieve, and inadvertent injury to these vessels is rarely clinically significant. Despite the exposure obtained with the skin incision, bleeding from the skin and various vascular structures eliminates a clear view of the field in most cases. Time does not permit the operator to attempt to deal with bleeding so as to achieve a bloodless field. Maintenance of the anatomic relationships outlined previously allows the procedure to be completed expeditiously without the need for direct visualization of the structures of interest. If significant bleeding occurs, it can be dealt with (usually by simple wound packing) after the airway has been secured.

Figure 31-8 A and B, A transverse incision is made in the cricothyroid membrane staying low to attempt to avoid the cricothyroid artery and vein.

(A adapted from and B from Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

Attempts at ventilation (which have to be discontinued at this point) may result in the presence of air bubbles appearing in the wound and tissues of the neck in synchrony with respirations. The index finger may also be reinserted into the opening to confirm the proper location of the incision in the membrane.

f Insertion of the Tracheal Hook

Laryngeal control should be maintained with the thumb and long finger of the nondominant hand. The hook is held in the dominant hand, turned so that it is oriented transversely, and then inserted into the trachea through the surgical opening (Fig. 31-9). The index finger of the nondominant hand can serve as a guide to help place the hook into the incision. Once through the CTM, the device hook is rotated so that the hook is oriented in the cephalad direction. The hook is firmly applied to the inferior border of the thyroid cartilage, and gentle upward and anterior traction with the hook handle at a 45-degree angle to the anterior neck skin can be used to bring the airway up to the skin (Fig. 31-10). The hook is then passed to an assistant to maintain immobilization and control of the larynx. The assistant will not release the hook under any circumstance until a definitive airway has been successfully inserted and placement is confirmed; thus the term “no drop technique.” The operator’s nondominant hand may then be released for completion of the procedure, with the proviso that the tracheal hook is maintaining control and should not be removed until confirmation of tube placement has been obtained.

Figure 31-9 The tracheal hook is inserted into the wound, oriented transversely, and then rotated to pick up the inferior edge of the thyroid cartilage.

(From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

Figure 31-10 A and B, The tracheal hook exerts light traction on the inferior aspect of the thyroid cartilage.

(A adapted from and B from Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

g Dilation of the Opening with Dilator

The Trousseau dilator is then inserted using the dominant hand. It is our preference to insert the dilator so that the prongs are oriented to dilate the opening in the rostral-caudal direction rather than transversely (Fig. 31-11). Although the dilator appears to be designed to insert directly into the airway and dilate transversely, it is the rostral-caudal dimension of the CTM that provides the most resistance to cannulation, so it is desirable to dilate in this plane. The Trousseau dilator is inserted only a couple of millimeters into the airway and then opened to dilate the airway. With the airway thus opened, the dilator, in situ, is transferred from the operator’s dominant hand to the nondominant hand, where it can be held from underneath (see Fig. 31-11). This frees the dominant hand to insert the tracheostomy tube.

Figure 31-11 A and B, The Trousseau dilator is used to enlarge the vertical dimension of the membrane, the aspect providing the most resistance to insertion of the tube.

(A adapted from and B from Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

h Insertion of the Tracheostomy Tube

The tracheostomy tube is then inserted with the obturator in place (Fig. 31-12). To avoid unnecessary delays at this juncture, the tube should have been removed from its packaging before initiation of the procedure and the blunt-tipped obturator should already have been inserted. The tube is oriented along the handle of the dilator (i.e., at a 90-degree angle to the patient) and inserted between the dilator blades, following their natural curve. As the tracheostomy tube gains the airway and is passing between the prongs of the Trousseau dilator, it is helpful to rotate the dilator handle counterclockwise 90 degrees (see Fig. 31-12) so that the dilation occurs in the transverse rather than the rostral-caudal dimension. The reason is that when the tracheostomy tube has gained access into the airway, the prongs of the Trousseau dilator may themselves inhibit successful passage of the tip of the tracheostomy tube down the trachea. Through rotation of the Trousseau dilator, the prongs are moved out of the way to either side of the tube, but dilation is continued to assist in placing the tracheostomy tube until it is firmly seated against the anterior neck. The dilator is gently removed as the tube is being advanced, just before it is seated in its final position (Fig. 31-13).

Figure 31-12 A and B, The tracheostomy tube is inserted, and the dilator can then be rotated counterclockwise 90 degrees to facilitate passage of the tube.

(A adapted from and B from Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

Figure 31-13 A and B, The tube is firmly seated, and the dilator can be removed. It is best to leave the hook in situ until placement is confirmed and the cuff has been inflated.

(A adapted from and B from Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

i Cuff Inflation and Securing the Tracheostomy Tube

The cuff should be inflated. The obturator is then removed, and the inner cannula, if one is present, is inserted to allow the attachment of the ventilation bag. Care must be taken during the initial assembly of the tracheostomy tube not to lose track of the inner cannula, which is needed for the attachment of ventilation devices. The tracheostomy tube can be secured with twill or with a padded fastener that goes around the neck and attaches to the neck plate of the tube.

j Confirmation of Tube Position

The tracheostomy tube position can be confirmed using the same methods as those used to confirm ETT position. Carbon dioxide detection can be used to confirm correct placement in the airway. If there is concern that the tube is placed outside the trachea, a nasogastric tube may be gently inserted. In the airway the tube advances easily, but resistance is met if the tube is in a false passage. Auscultation of both lungs and the epigastric area is also recommended, although esophageal placement of the tube is highly unlikely. A chest radiograph can be helpful in the identification of barotrauma. Only after the position of the tube is certain should the tracheal hook be removed. This should be done with great care to avoid hooking a part of the tracheostomy tube and inadvertently extubating the patient. If the tube was inadvertently placed in a false passage, correction is greatly facilitated with the hook still in place.

2 Rapid Four-Step Technique

The rapid four-step technique (RFST) is an attempt to simplify the cricothyrotomy procedure by using a horizontal stab incision through the skin and membrane simultaneously, followed by tracheal hook traction applied caudad at the cricoid ring.¹⁶ Cadaveric studies have shown RFST to be simple to learn and faster in obtaining a surgical airway than the open technique just described.⁵⁰^–⁵² Other advantages include the following: (1) less equipment is necessary (it is performed with a scalpel, hook, and tracheostomy tube); (2) it may be performed independently; and (3) the operator is positioned at the head of the bed, similar to the stance for performance of orotracheal intubation.

Acute complications from RFST may be more common than with the traditional “no-drop” method. The stab technique may increase the incidence of trauma to the posterior trachea and anterior aspect of the esophagus. In cadaveric models, an increase in damage to the cricoid ring due to direct traction on the ring with the tracheal hook was found.^1,⁵⁰^–⁵² This may be remedied through the use of a double-hook device that disperses the forces across the cricoid ring.^1,⁵¹

RFST may not be as desirable in patients in whom landmark identification is difficult. In this circumstance, we recommend beginning with a vertical incision, similar to the traditional technique described previously.¹⁶ There are no clinical studies that report the success rates and associated acute and delayed complications of RFST compared with traditional methods in live patients. The choice between the RFST and the traditional technique is an individual one, because there is no clear evidence that either method is superior or more likely to bring success than the other.

As with other techniques, attempts should be made to oxygenate and ventilate the patient maximally before and during the procedure. The anterior neck should be prepared as described earlier for the “no-drop” technique. From a position at the head of the bed, RFST is performed in the following manner.

a Landmark Identification

As in traditional cricothyrotomy, the airway is accessed through the CTM. Therefore, the identification of landmarks is exactly the same as described previously (Fig. 31-14; see Fig. 31-5). Because of the horizontal stab incision, however, it is even more critical to be confident of the location of the membrane. If there is uncertainty, it is recommended to begin with a vertical incision first, as described earlier.

Figure 31-14 The landmarks are palpated as for the “no-drop” technique, but the horizontal skin incision leaves little room for error, so extra care is needed.

(From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

b Horizontal Stab Incision

A single horizontal stab incision using a no. 20 scalpel is made directly through the skin, subcutaneous tissues, and CTM. The incision should be approximately 1.5 cm wide, and because of the size of the no. 20 blade, widening of the opening is rarely required (Fig. 31-15). If the anatomy is not readily palpable through the skin, an initial vertical incision should be created to allow subsequent palpation of the anatomy and identification of the CTM. Once the CTM has been incised, the no. 20 blade is maintained in the airway until the tracheal hook is secured.

Figure 31-15 A single, horizontal, stab incision is made through skin and membrane.

(From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

c Stabilization of the Larynx with the Tracheal Hook

A tracheal hook is placed parallel to the scalpel on the caudal side of the blade (Fig. 31-16). The hook is rotated to secure and control the cricoid ring, and the scalpel is then removed from the airway. The tracheal hook is used to apply gentle traction on the cricoid ring to lift the airway up toward the surface of the skin and to provide modest stoma dilation (Fig. 31-17). The direction of force on the hook is reminiscent of the “up and away” direction employed with laryngoscopy. The amount of traction force required for easy intubation (18 newtons) is significantly lower than the force that is associated with breakage of the cricoid ring (54 newtons); however, the chance of trauma may be further reduced by using a double-tined hook.¹ Use of the hook in this direction usually provides sufficient widening of the incision to obviate the need for further dilation (i.e., Trousseau dilator). Placement of the hook on the cricoid ring may also reduce the possibility of intubating the pretracheal potential space, which is essentially eliminated due to the apposition of the airway and the subcutaneous fat by the traction on the hook.

Figure 31-16 The hook is oriented transversely and inserted alongside the scalpel before the scalpel is removed.

(From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

Figure 31-17 The hook exerts traction on the superior aspect of the cricoid cartilage and skin, pulling the airway up into the field.

(From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

d Insertion of the Tracheostomy Tube

With adequate control of the airway using the hook placed on the cricoid ring, a tracheostomy tube is gently inserted through the cricothyroid space into the trachea (Fig. 31-18). The cuff is then inflated, the tube is secured, and its location is confirmed by the same methods described earlier.

Figure 31-18 The tracheostomy tube is inserted and then verified and secured in the usual fashion.

(From Walls RM, Luten RC, Murphy MF, Schneider RE: Manual of emergency airway management, ed 2, Philadelphia, 2004, Lippincott Williams & Wilkins.)

3 Percutaneous Cricothyrotomy Techniques

Numerous commercial cricothyrotomy devices are available, many of which use a modified Seldinger technique to assist in the placement of a tracheal airway (see Fig. 31-4). There are aspects of this technique that may make it appealing to the anesthesiologist. This method is similar to the one commonly used for placement of central venous catheters and offers some familiarity to the operator who is uncomfortable or inexperienced with the surgical cricothyrotomy technique described earlier. This technique can be learned quickly. By the fifth practice attempt on a mannequin model, 96% of anesthesiologists achieved success within 40 seconds.⁶ However, the technique still requires knowledge of the anatomy and the ability to localize the membrane and has several steps, so it approaches the open technique in complexity. When compared with the standard open technique in cadavers and dog models, there were no differences in performance times or complications.⁵³^–⁵⁵ It is estimated that the procedure may be accomplished in 40 to 100 seconds.^6,^27,⁵³^–⁵⁵ Also, the percutaneous cricothyrotomy kits are preassembled and commercially available, whereas at present the surgical tools used in the traditional approach are not (except in the combination kit shown in Fig. 31-4). It seems intuitive that the percutaneous technique should result in less bleeding, but no studies have been performed to assess the significance of any difference. One of the limitations is the relatively smaller lumen, which is of no real concern in an emergency, and in some models the absence of a cuff, which could be an issue if airway protection from emesis or hemorrhage is needed. It is suggested that a device with a cuff be selected, because many of these procedures are performed on patients who have not been fasted or are actively hemorrhaging and require further airway protection. The Melker Cuffed Emergency Cricothyrotomy Catheter Set and the Melker Universal Cricothyrotomy Set are available with a cuffed airway catheter (Cook Critical Care).

As with other techniques, attempts should be made to preoxygenate and ventilate the patient maximally before and during the procedure. The anterior neck should be prepared as described earlier. Although the kits may vary, most of the percutaneous cricothyrotomy kits use the Seldinger technique and share the following steps.

a Landmark Identification

The CTM is identified using the same methods described previously. The nondominant hand is then used to control the larynx and maintain identification of the landmarks.

b Insertion of Locator Needle

The introducer needle is then inserted through the skin and the CTM in a slightly caudal direction. The needle is attached to a syringe and advanced with the dominant hand while negative pressure is maintained on the syringe. The sudden aspiration of air indicates placement of the needle into the tracheal lumen (Fig. 31-19).

Figure 31-19 The finder needle is inserted through the cricothyroid membrane. A small, vertical skin incision may be made before insertion of the needle or later, just before insertion of the airway and dilator.

(Photograph from STRATUS Center for Medical Simulation, Brigham and Women’s Hospital, Boston, MA, used with permission.)

c Insertion of the Guidewire

The syringe is then removed from the needle, and a soft-tipped guidewire is inserted through the needle into the trachea in a caudal direction. The needle is then removed, leaving the wire in place. As with most Seldinger techniques, control of the wire must be maintained at all times (Fig. 31-20).

Figure 31-20 The wire is fed through in a caudad direction; then the needle is removed.

(Photograph from STRATUS Center for Medical Simulation, Brigham and Women’s Hospital, Boston, MA, used with permission.)

d Skin Incision

A small skin incision is then made adjacent to the wire. This facilitates passage of the airway device through the skin. Alternatively, the skin incision may be made vertically over the membrane before insertion of the needle and guidewire.

e Insertion of the Airway

The airway catheter provided in the kit (3 to 6 mm internal diameter), with an introducing dilator in place, is then inserted over the wire into the trachea. If resistance is met, the skin incision should be deepened and a gentle twisting motion applied to the airway device (Fig. 31-21). After the airway device is firmly seated against the skin, the wire and obturator are removed together, leaving the tracheostomy tube in place. Tube location should then be confirmed, as described previously, and secured properly. The devices are radiopaque.

Figure 31-21 A, The airway is inserted over the guidewire with the dilator in place. B, The dilator and wire are then removed together.

(Photograph from STRATUS Center for Medical Simulation, Brigham and Women’s Hospital, Boston, MA, used with permission.)

IV Training Issues

A survey published in 1995 found that although 80% of anesthesiology programs taught cricothyrotomy as part of their curriculum, most of them did so through lectures only, with no practical experience.²¹ In a survey published in 2003, only 21% of anesthesiologists claimed skills to perform cricothyrotomy.⁵⁶ Most anesthesiology graduates have never performed a cricothyrotomy during their training.⁶

The merits of a procedure are irrelevant if hesitancy on the part of the provider leads to a significant delay in establishing a definitive airway. Discomfort with a procedure is usually overcome with technical proficiency obtained through stepwise practice; however, this procedure is performed so rarely that proficiency must be obtained through scheduled, simulated learning. Invasive airway methods, like any other invasive procedures, must be learned and practiced at regular intervals to maintain proficiency.

The advent of emergency medicine as a specialty with its own airway expertise has resulted in a significant decrease in exposure to emergency airways for anesthesiology trainees. The success of RSI in the emergency setting, as well as advances in airway management techniques in anesthesiology, have prompted editorials concerned with the problem of gaining and maintaining competence in invasive airway management.⁵⁷^–⁵⁹ Studies suggest a current cricothyrotomy rate of approximately 1% of all emergency airways and a dramatically lower rate in the operating suite. Regardless of the setting, this incidence is too low to ensure adequate training, but it highlights the probability that most airway managers will be called on to perform an invasive airway at some point in their career.

The practice required to obtain familiarity with the equipment and technique must take place outside the clinical setting. Of anesthesiology programs that instruct their residents on cricothyrotomy, 60% use lectures only, which is a poor teaching technique for developing proficiency in manual skills.²¹ One study using a mannequin model determined that five cricothyrotomies were necessary to reach a steady performance state in which the procedure could be completed in 40 seconds.²⁵

No studies have identified the optimal interval between training episodes for retention, although one small report suggested increased retention when training was repeated monthly versus every 3 months.³⁸ Studies in cadavers performed primarily to compare different surgical airway techniques incidentally identified a similar rapid learning curve.^60,⁶¹ There are no studies examining the clinical correlation of these training techniques, but the high success rate of emergency cricothyrotomy suggests that retention and competence have occurred.

On the basis of the limited available literature, some recommendations regarding the learning and retention of invasive airway techniques can be made: (1) identify a preferred method of invasive airway management that is immediately available; (2) become trained in the procedure by performing a sufficient number of repetitions under the supervision of a qualified instructor, using an animal or simulator model, or both; and (3) practice the technique in one to two refresher sessions per year on animal or simulator models, with five repetitions per session.

Animal tracheas may be obtained from a slaughterhouse at relatively low cost, and the technique may be attempted multiple times on each specimen (pigs and sheep are most commonly used). Simulators represent a significant capital investment, but newer simulators are much less expensive and much simpler to operate than older models. Models specifically for cricothyrotomy training are also available. Formal training under expert guidance is available through some difficult airway continuing medical education (CME) courses.