Chapter 3. The Failed Airway

The airway management of unstable and critically ill patients has always been an essential skill within the emergency physician's scope of practice. The early act of inserting an artificial airway protects the lungs from aspiration in an obtunded patient, or prevents hypoxia and carbon dioxide retention in a patient who cannot spontaneously breathe. This has been shown to improve neurologic outcome when performed early during the initial phase of resuscitation, and emergency physicians are often the first clinicians to perform intubation and initiate mechanical ventilation.1

While direct laryngoscopy is associated with a high rate of success with few adverse events when performed by personnel skilled in its use, there are a number of clinical scenarios and presentations in which direct or indirect laryngoscopic intubation is difficult or impossible. Disruption of the normal anatomy due to body habitus, medical and surgical disease, or facial and oral trauma can result in soft tissue and bony structure distortion. Obstruction or lack of laryngeal visualization can be caused by copious amounts of blood or vomitus, facial edema, vocal cord swelling from prolonged or multiple intubation attempts, anaphylaxis, angioedema, and burns. When an emergency physician is called upon to perform urgent airway management, the approach to airway management should be standardized and similar in all contexts. Whether in the field with an emergency medical services (EMS) agency or in the hospital, a clinician should recognize when to abort further attempts at intubation through direct visualization and proceed to alternative techniques for establishing an artificial airway. As discussed in the preceding chapter, inability to identify the vocal cords should prompt the use of a “difficult airway” algorithm that includes the use of intubation adjuncts such as tracheal tube introducers, alternative intubation devices such as video laryngoscopes, flexible fiberoptic scopes, lighted stylets, retrograde approaches, or the placement of a laryngeal mask airway (LMA).

When intubation is not successful, especially after administration of neuromuscular blockade, and when adequate oxygenation or ventilation with the bag–valve–mask technique cannot be achieved, a “failed airway” has occurred. At this point, cricothyroidotomy is the emergency medicine surgical airway of choice.2,3 It should be noted that the terms cricothyroidotomy and cricothyrotomy are synonymous and may be used interchangeably.

Fortunately, the incidence of the “failed airway” in the emergency department (ED) setting is low. Depending on the patient population and the skill level of the clinician, airway management databases report the use of a surgical airway in 0.03–1.8% of patients who require definitive airway management.4–8 When it does occur, a “failed airway,” sometimes referred to as a “cannot intubate–cannot ventilate” situation, requires a surgical airway be placed immediately. Unfortunately, when required, the establishment of an emergency surgical airway is associated with a high rate of complications, up to 14% in some reviews.9

Despite newer equipment and modified approaches, there remain two traditional, emergent surgical airway procedures: surgical open cricothyroidotomy and needle cricothyroidotomy. Both approaches require a firm understanding of the involved anatomy for a successful procedure, and a familiarity with the potential limitations and complications of each technique. Preparedness is the key to success.

This procedure has limited contraindications. Cricothyroidotomy should not be done if oral or nasal intubation has not been attempted or if there is significant trauma to the area, such as fracture of the larynx or transection of the trachea.

The surgical approach is contraindicated in children younger than 10–14 years old due to the underdeveloped larynx; however, the exact age cutoff is not well established in the medical literature. The cricoid ring in children is the narrowest portion of the airway, much like a funnel, with the vocal cords being the widest space. This is generally the opposite in the adult. For this reason, needle cricothyroidotomy is the preferred airway in young children.

The cricothyroid membrane is located between the thyroid and cricoid cartilages (Figure 3-1A). Both structures are usually easy to palpate in a patient with normal anatomy. In the edematous intensive care unit (ICU) patient, the anatomy can be extremely difficult to palpate. By applying pressure over the area of the larynx for several seconds, however, the edema fluid will be dispersed and the anatomic landmarks may be appreciated. Blindly, the cricothyroid membrane can be found approximately one third the distance from the manubrium to the chin, in the midline, in patients with a normal habitus (Figure 3-1B).

The thyroid cartilage is the largest cartilage on the anterior neck. Inferior to the thyroid cartilage is the beginning of the cricothyroid membrane. The superior thyroid prominence, which is often very obvious and is commonly referred to as the “Adam's apple,” is the most important landmark for cricothyroidotomy. The cricothyroid artery and vein, which are branches of the superior thyroid artery and vein, run closer to the superior border of the membrane at the inferior portion of the thyroid cartilage. These vessels anastomose in the middle of the membrane (Figure 3-1C). There are usually no vessels at the lower part of the membrane near the superior aspect of the cricoid cartilage; however, a small percentage of patients may have a “thyroid ima” artery that may pass over the inferior portion of the membrane.

In the adult size patient, a surgical cricothyroidotomy is the preferred approach. Only an open surgical cricothyroidotomy—but not a needle cricothyroidotomy—establishes a definitive airway with a cuffed tube in the trachea, and provides a means for adequate artificial oxygenation and ventilation, allowing the resuscitation to continue. The needle method should only be used as a temporizing method until an open cricothyroidotomy or a tracheostomy can be performed due to the ease of catheter dislodgement and bending. The less optimal ventilation with needle cricothyroidotomy can also cause hypercapnia, which will worsen acidosis.

Cricothyroidotomy, rather than tracheostomy, is the preferred initial surgical airway of choice for the failed airway patient. Emergency tracheostomy has a more severe set of complications, such as posterior tracheal laceration, esophageal perforation, and pneumothorax. It is also technically more challenging, even in the percutaneous approach. Tracheostomy, however, is a definitive airway and should be reserved for placement under well-controlled conditions.

Although the emergent need for cricothyroidotomy usually precludes establishing optimal conditions, such as obtaining consent, everything possible should be done to use sterile technique if feasible. In every circumstance, gloves and a face shield with mask should be worn by the proceduralist. Suction should be available. Furthermore, time should be taken to position the patient in a supine position with the neck extended if no cervical injuries are suspected. The patient should remain on supplemental oxygen as long as it does not interfere with or alter the anatomic landmarks.

ICU beds are not generally suitable for any operation: the beds are wider than an operating room (OR) table or ED stretcher and the operator is further away from the patient and therefore must bend over considerably. If the procedure must be performed in an ICU bed, the patient should be moved as close to the side of the operator as possible. If time permits, prepare the neck using either povidone iodine or chlorhexidine solution. The appropriate equipment for the planned technique should be ready and available (Table 3-1).

One of the major problems with performing surgical and needle cricothyroidotomy is the lack of experience among most practitioners. Furthermore, even among those with experience, or who have practiced extensively under laboratory conditions, skills maintenance is difficult at best. There are simply too few opportunities to clinically utilize this important skill on a regular basis. A 5-year review at the Hennepin County ED found that cricothyroidotomy was performed in only 1% of intubations.10

Given the complexity and importance of the skill set, other techniques and equipment have been developed. The Seldinger technique for percutaneous cricothyroidotomy has many advantages over open cricothyroidotomy. First and foremost is comfort. Although open cricothyroidotomy has traditionally been taught as the airway management maneuver of last resort, the large number of other procedures done percutaneously with Seldinger technique—such as central lines and some arterial lines and chest tubes—make this approach a logical choice for many practitioners. This technique is more continuous with procedures more commonly performed. Commercial Seldinger cricothyroidotomy kits are available such as the Cook® Melker kit (Figure 3-2).

There are also good data to show that the Seldinger technique yields better outcomes when compared with open cricothyroidotomy. Schaumann et al showed that not only did the Seldinger technique result in a shorter time to successful ventilation, but it resulted in fewer injuries as well.11 It is also worth discussing the one unique piece of equipment for this procedure, a commercially available cuffed emergency cricothyroidotomy catheter (Figure 3-3) that looks similar to a tracheostomy tube but with a 5-mm diameter. Much like a tracheostomy tube, it comes with a dilator as well. One advantage of the Melker kit is that it can be used for both the Seldinger technique and the open technique, so that in the chaotic environment of the ED everything necessary is readily available. If a commercial kit is not available, it is recommended that a kit be prepared ahead of time with all the necessary equipment to prevent delay. Keep in mind that the inner diameter of the tube should not exceed 6 mm. A 6.0- or 5.0-mm ID cuffed endotracheal tube (ETT) should be used if a cuffed emergency cricothyroidotomy catheter is not available. It is important to recognize, however, that it can be difficult to secure an ETT and that there is a risk of dislodgement or right main stem bronchus intubation. Familiarity with the type of equipment available, as well as its location, is essential for the success of this procedure.

1. Open technique:

   1. The practitioner stands to one side of the patient at the level of the neck. A right-handed practitioner should stand on the patient's right side, a left-handed practitioner to the left.

   2. The cricoid ring is located by placing the index finger at the sternal notch and palpating cephalad until the first rigid structure is felt. This is the cricoid ring. Rolling the index finger one finger breath above should locate the “hollow” between the cricoid and thyroid cartilages. This is the cricothyroid membrane. One may also choose to locate the thyroid prominence at the midline of the thyroid cartilage, holding the cartilage in place with the nondominant hand, and rolling the index finger caudally by 1 or 2 cm until a small depression or “hollow” is felt. This is the cricothyroid membrane. This may be the technique of choice in an edematous patient or a patient with a larger neck. Attention should be paid to the vessels that run at the superior border of the membrane. In severe bleeding, or whenever a landmark cannot be located, a skin incision is made and a finger should be used to locate a key landmark.

   3. The thumb and middle finger of the nondominant hand are then used to stabilize the two cartilages.

   4. A vertical skin incision is then made in the midline of the region between the two cartilages. A vertical skin incision is crucial because this incision can be extended if it is too high or too low, whereas a horizontal incision would require a new incision. Also, a vertical midline skin incision has less chance of cutting a vessel. The initial incision should go through the skin and subcutaneous tissues, but no deeper because of the risk of injuring the cricoid or thyroid cartilages or vascular structures.

   5. With the scalpel blade now positioned horizontally, the cricothyroid membrane is perforated at the midline inferior portion of the membrane using a horizontal stabbing motion. The reason for the horizontal cut is to have a good horizontal aperture and to not cut the cricoid cartilage with the scalpel blade. The scalpel blade will slice the cricoid cartilage if inserted vertically. The blade should only enter the membrane by 1 cm in order to avoid complications.

   6. Insert the back end of the scalpel handle through the cricothyroid membrane incision and rotate it 90° to widen the opening. The handle is slightly wider than the width of the blade.

   7. Finally, the ETT tube can be placed in the opening and the balloon inflated as in a traditional intubation. With the practitioner holding the ETT in place, the tube can be connected to a bag–valve–mask, and tube placement should be confirmed as with a traditional intubation (auscultation, color capnometry, esophageal detector, etc.).

   8. Finally, the tube is secured with a ribbon or adhesive tape.

   9. As always, a portable chest x-ray should be obtained to assure proper placement of the tube relative to the carina and to check for pneumothorax.

2. Seldinger technique: The procedure here is based on the Cook Melker kit.

   1. Open the kit and insert the dilator with wire into the airway catheter (there are two dilators in the kit: one with a hole for the guidewire and one for the open technique that is blunted).

   2. The cricothyroid membrane is located in same manner as with the open surgical technique.

   3. Attach the needle with the sheath to the syringe and fill the syringe with a small amount of water or saline. Insert the needle into the cricothyroid membrane. With the tip of the needle pointing to the feet in a 45–50° angle, gently puncture the membrane until bubbles are apparent in the syringe. This will confirm you are in the trachea. Use slow, gentle pressure so as not to damage the posterior wall of the trachea.

   4. As soon as there is a “bubble” of air in the syringe (signaling entrance into the lumen of the larynx) (Figure 3-4), the sheath is advanced over the needle and into the larynx, still at 45°. As with advancing an ETT via a surgical cricothyroidotomy, overzealous posterior advancement of the sheath may cause the sheath to get stuck on the cricoid cartilage posteriorly. In this case, the syringe with sheath should be withdrawn slightly, and readvanced taking care not to displace the sheath posteriorly.

   5. Once placed, the needle can be removed leaving the sheath in place in the larynx/trachea. The wire should be advanced through the sheath (Figure 3-5). The plastic sheath is then removed leaving only the wire in place.

   6. With the provided 15-blade scalpel, a 0.5-cm vertical skin incision should be made on both sides of the wire (taking care not to cut the wire). Remember that the catheter size is 0.5 cm so a slightly larger incision will be necessary.

   7. Insert the external end of the wire into the dilator, which was already placed into the cricothyroidotomy catheter. Advance them as a unit, following the curvature of the dilator, through the subcutaneous tissue and into the trachea. A twisting motion may be required so as not to bend the wire. Advance until the cricothyroidotomy catheter is flush against the skin (Figure 3-6). Once in place, the dilator is removed and the cuff inflated.

   8. Secure the cricothyroidotomy catheter with the provided wrap. Confirm placement as discussed in the section “Surgical Technique.”

3. Holmes et al reported a rapid four-step technique, a modified version of the open surgical technique that was found to be easier and quicker (performed in one third the time) when compared with the open technique.12 In another variation, Hill et al found that insertion of a tracheal tube directly through the incision was challenging and modified the technique by placing a bougie through the incision. The cricothyroidotomy catheter was then advanced over the bougie. In their randomized study conducted on sheep, they found that this was easier and faster to perform.13

Needle cricothyroidotomy is the preferred emergency surgical airway technique in patients under the age of 10–14 years. This is because larger endotracheal or tracheostomy tubes placed through the cricothyroid membrane have a high complication rate in this age group as previously discussed.14 Ventilation may be achieved, poorly, for approximately 20–30 minutes in a patient with normal lungs, which makes this procedure an inappropriate choice in a sick ICU patient. Furthermore, the airway established by a needle cricothyroidotomy is only a temporary measure. This measure will, however, provide an additional 30 minutes or so until a more definite airway can be established. Note that even if placed correctly, there will be great resistance to ventilatory airflow because of the small lumen of the 12- or 14-gauge catheter.

See Table 3-2 for the needle cricothyroidotomy equipment.

Needle Cricothyroidotomy Technique

1. The cricothyroid membrane is located in the same manner and, as with a surgical cricothyroidotomy, the thumb and middle finger of the nondominant hand are used to stabilize the two cartilages.

2. A sheathed 14- or 12-gauge needle with a syringe attached is placed over the location of the cricothyroid membrane at 90° to the skin. Adding water or saline will create a “bubble” once air is aspirated from the trachea. If no water is added, a “gush” of air into the syringe will confirm tracheal placement.

3. Once the needle is in the trachea, the needle should be angled 45° caudally. The sheath is then advanced and the needle is removed. As with advancing an ETT via a surgical cricothyroidotomy, overzealous posterior advancement of the sheath may cause the sheath to get stuck on the cricoid cartilage posteriorly.

4. The adapter from the end of a 3.0-mm ID ETT can be attached to the end of the catheter, and an Ambu bag or ventilator attached to the adapter. Alternately, a 3-mL syringe (without plunger) can be attached to the catheter to “step up” the size of the connection. An adaptor from the end of a 7.0-mm ID ETT can then be attached to the syringe barrel and the Ambu bag or ventilator can be attached to the adapter.

5. The catheter must be held in place manually by a provider until a proper tracheostomy is performed (which should be immediately). Because of the pressure delivered through the small lumen, the sheath cannot be secured with tape or any other device; it must be manually held in place.

6. While preparations are being made for an emergent tracheostomy, a chest x-ray should be obtained. Massive subcutaneous air could imply misplacement of the catheter into the subcutaneous tissues of the neck.

The question frequently arises as to how long to leave a cricothyroidotomy tube in place in the larynx and at what point it should be converted to a formal tracheostomy. A tube left in place in the narrow space between the two cartilages can erode either one or both of these cartilages and bacterial chondritis may occur. This can lead to scarring and subsequent laryngeal or tracheal stenosis with loss of laryngeal function. As a rule of thumb, if the airway will be needed for more than 2 days, the cricothyroidotomy should be changed to a tracheostomy; otherwise, the cricothyroidotomy tube may be left in place. For example, in a patient who needs a surgical airway because of anaphylactic or angioedema-related airway swelling, the condition may resolve in a matter of hours, allowing for simple decannulation. If the cricothyroidotomy is to be converted to a tracheostomy, it should be done in a controlled setting with proper instruments and lighting by an appropriate practitioner, whether a surgeon in an OR or an intensivist in the ICU.

Needle cricothyroidotomy and surgical cricothyroidotomy (whether done in an open manner or with the Seldinger technique) share some common complications.

Bleeding may occur, especially if the thyroid ima artery is injured. This artery is present in 4–10% of individuals, arises from the aorta or brachiocephalic artery, stays in the midline, and may travel cephalad as high as the thyroid cartilage.15 Once an injury to this artery is recognized, the patient should be taken to the OR to have the artery controlled by ligation. Most bleeding, however, is from small branches of the anterior jugular veins. These veins usually have very high venous pressures due to the high airway pressure in many sick ventilated ICU patients, or in the patient trying to breathe against an obstructed airway (Valsalva). Once the airway is obtained, the intravenous pressure drops and the bleeding usually stops.

Pneumothorax from placement of a surgical airway is usually due to barotrauma from forceful ventilation and high airway pressures toward the end of the procedure. Once the airway is secure, a pneumothorax should be treated just as one that arose from any other condition, with tube thoracostomy.

In an obese or edematous neck or in one with altered anatomy from a tumor or prior surgery, it is possible to misplace the cricothyroidotomy catheter, ETT, or needle anterior to the larynx and trachea and into the mediastinum. Ventilation in this setting is obviously not possible. Manifestations of an incorrectly positioned tube are high airway pressures, absent breath sounds, and massive subcutaneous emphysema. When a malpositioned tube is recognized, the tube should be removed and a second attempt should be made.

Laceration or perforation of the structures of the neck, such as the trachea, esophagus, or recurrent laryngeal nerves, is extremely rare and is usually due to inadequate knowledge of the anatomy of the neck. Laceration of the thyroid ima artery, when present, may be unavoidable because it cannot be visualized through the incision.

Late airway complications may occur in up to 52% of cases. These complications include voice changes and laryngeal and/or tracheal stenosis.16–19 They usually manifest after the course of the critical illness and are not emergent conditions, although they require evaluation and treatment as they may be debilitating for the patient.