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Gone are the days of rampant cricothyrotomies, yet the competent emergency physician needs to know the ins and outs of the surgical airway.   

Thirty years ago a surgical airway was considered the ultimate means of rescue ventilation and rescue intubation. Today, it is neither. The LMA, similar devices, and the King LT (or Combitube) have become the default means of rescue ventilation when mask ventilation fails. Video laryngoscopes have become the default means of rescue intubation if direct laryngoscopy fails. When I started at Bellevue Hospital in NYC, a major trauma center with over 100,000 ED visits, one third of the trauma airways were managed with cricothyrotomy. This was in a setting where RSI was infrequent and it was believed that a cervical collar was a contraindication to oral intubation. Within ten years, after the establishment of an EM program, and routine use of RSI, the incidence became less than a handful a year. Most ED physicians trained in the last twenty years have had limited or no experience with an emergent surgical airway.

Surgical airways require approximately 100 seconds until ventilation. If the procedure is begun on a dead patient it rarely changes the outcome. The best surgical airways are initiated on patients without significant hypoxia, in whom the procedure can be done carefully and methodically. In many emergency airways the potential need for a surgical airway (difficulty with both rescue intubation and rescue ventilation) is predictable. Such common examples are extreme facial trauma, and pathology about the upper airway like Ludwig’s Angina, angioedema, head and neck cancers, and laryngeal fractures. With foreign bodies stuck in the upper airway it may only become evident after failed efforts at intubation and inability to pass a tracheal tube. For emergency patients with distorted oral and supraglottic anatomy in whom a surgical airway is an inevitable part of their care, the surgical airway may be the best choice for intubation. If time permits and consultation is available, the OR is a better venue for the procedure than the ED. Not uncommonly, this is not an option in emergency airways. When the pathology is at the level of the larynx (laryngeal fracture or neoplasm), a tracheostomy – not a cricothyrotomy – is probably needed. The following discussion applies to cricothyrotomy.

Commonly available surgical airways in emergency departments include wire-guided or needle guided percutaneous devices, large trocars with overlying catheters, and traditional open surgical airway kits. In order to become proficient deploying these devices in the time period required, it is mandatory that practitioners familiarize themselves with the specific equipment kept in their department. For the purposes of this article we will specifically review the most common percutaneous device, the Melker kit (Cook Critical Care), and the open techniques (standard and Rapid Four-Step).

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Like many procedures in emergency medicine, planning and positioning is critical. First, maximize oxygenation as much as possible. Leave the patient upright as much as you can. Head elevation, up to 45 degrees, improves pulmonary function, lessens risk of regurgitation, and decreases the amount of blood that will pool at the surgical site. To maximize FiO2 combine face-mask oxygenation with nasal cannula. Heliox is useful to reduce resistance and turbulent flow, and lessen the work of breathing in situations of airway narrowing.

Anesthetizing the airway is helpful to minimize bucking and coughing as the trachea is entered. This can be done with topical sprays at the base of the tongue (LMA MADgic) or more effectively through nebulized lidocaine. Alternatively, trans-tracheal puncture (3 cc of lidocaine, using a short 23 gauge needle) through the cricothyroid membrane is fast and simple. Depending on patient agitation and cooperation, small aliquots of IV ketamine (10-20 mg) can be titrated to effect to minimize patient movement. I have usually combined this with a small dose of midazolam, although the need for concurrent benzodiazepines to prevent emergence reactions is debated. If adjunctive medications are used, it may be necessary to maintain the patient upright and distract the mandible forward to maintain airway patency.

Few physicians are equally skilled performing fine motor tasks with each hand. I find it far easier when performing a surgical airway to be positioned to the patient’s right side (lateral to their right upper thorax). This allows me to keep my non-dominant left hand on the thyroid, while using my right hand to manipulate instruments.

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Landmark identification is critical. The cartilages of the neck make up a rhomboid structure from the hyoid to the thyroid and the cricoid [see images]. In males the thyroid notch and cartilage is quite prominent; it makes sense to move down from the thyroid to the cricothyroid membrane. In females, coming up from the sternal notch and the cricoid is more useful. The cricothyroid membrane is approximately three finger-breaths above the sternal notch.

The Melker Cricothyrotomy Kit (Cook Critical Care) uses a Seldinger approach and a dilator in order to insert a specialized short airway catheter. Unlike some smaller, needle guided surgical catheters, the Melker is available in a 5.0 mm cuffed form. For emergency airways, the placement of a cuffed catheter is critical. In order to prevent aspirating a skin plug, and improve the likelihood of recognizing air aspiration, a small incision (<1 cm) at the cricothyroid membrane should be done first. A few cc’s of water in the syringe will permit recognition of bubbles and air aspiration upon insertion. The syringe is then removed and the wire inserted through the needle. Although the Melker does have a dilator, in my experience the larger the incision made on the wire, the easier it will be to insert the dilator and catheter. As the dilator and catheter is introduced over the wire, a fair amount of force may be needed. Unless the dilator and catheter are held rigidly together, they will separate [image]. Any gap between the wire, dilator, and catheter will prevent insertion, especially if the skin incision and cricothyroid membrane incision is not large enough. After insertion of both the dilator and catheter into the trachea, the wire and dilator are removed.

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For most emergent surgical airways I advocate using an open approach. If the cricothyroid membrane is obvious, cutting through skin and membrane is fastest. If the landmark is uncertain, a vertical incision and blunt dissection (with forefinger or clamps) is used to identify the membrane. The Rapid Four Step technique uses a larger scalpel (#20) that cuts through both skin and membrane. Regardless of what type of scalpel blade is chosen, the cricothyroid membrane is always incised horizontally. A tracheal hook has a small sharp point that pierces the membrane and then permits traction on the thyroid superiorly (or cricoid inferiorly). The hook lifts up the trachea while the membrane is cut. After incision through the membrane, in a spontaneously breathing patient, air will forcefully move through the incision and the patient will cough. If a hook is not used, leave your forefinger, clamp, or base of scalpel inside the trachea until the tube is inserted.

The cricothyroid membrane has an average vertical height of 8-11 mm. It is far easier to insert a small diameter (6.0 mm ID) tracheal tube than a Shiley catheter. Since the cricothyroid membrane is below the vocal cords (the distance from the cords to the cricoid is 1-2 cm), and the distance from the vocal cords to the carina is approximately 10 centimeters, only a small section of the tube needs to be inserted. Carefully check the markings on the tube to avoid main-stem intubation.

The OD of a 6.0 Shiley is 10.8 mm. If a Shiley is used, it is best to use a 4.0 mm ID cuffed version. On insertion the orientation of the Shiley (with the trocar inside it) must be perpendicular to the orientation of the trachea (i.e., it is inserted from the side until the tip is introduced, and then the catheter is pivoted caudally, parallel to the trachea to allow full insertion). If the tip is inserted directly from above, parallel to the trachea, the curvature and rigidity of the Shiley typically prevents tracheal entry. Once the Shiley has been inserted, the trocar is removed and the inner cannula—which has a 15 mm connection—is necessary to ventilate the patient.

Verify ventilation through a surgical airway using clinical signs, pulse oximetry, confirmation of end-tidal CO2, and chest radiography. If the patient deteriorates after an emergency airway consider pneumothorax resulting from air dissection into the thorax.


Dr. Levitan teaches emergency medicine at Jefferson Medical College and at the Univ. of Maryland and helps run a monthly airway management course involving specially prepared cadavers:
jeffline.jefferson.edu/jeffcme/Airway

 

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