Cricothyrotomy and Percutaneous Translaryngeal Ventilation

Indications and Contraindications

The chief indication for surgical cricothyrotomy is an inability to secure the airway with less invasive techniques in a patient with impending or ongoing hypoxia.

Surgical cricothyrotomy, like any invasive procedure, is associated with significant complications and should not be attempted until less invasive measures have failed. No simple algorithm fits all cases. When time and the clinical situation allow, it may be appropriate to attempt to intubate multiple times with traditional laryngoscopy or to try alternative intubation techniques. Emergency decisions are subject to controversy and differ on a case-by-case analysis, but alternatives to cricothyrotomy include bag-valve-mask ventilation, the gum elastic bougie, and laryngeal mask airways. At some point, further attempts at intubation become futile and the benefits of a surgical airway outweigh the risks associated with ongoing hypoxia.

When approaching a patient with a compromised airway, the clinician must have a clear potential algorithm in mind with a well-defined plan that shifts the airway approach from laryngoscopy to alternative techniques, and then to cricothyrotomy. The first step in deciding whether cricothyrotomy is indicated is anticipating a possible difficult intubation.

Several studies in the anesthesia and emergency medicine literature have attempted to identify predictors of a difficult airway. A Mallampati score can be determined in cooperative patients who are able to sit upright. It classifies the degree that the faucial pillars, soft palate, and uvula can be visualized ( Fig. 6.3 ). A higher score predicts a more difficult ET intubation. A Mallampati score can be obtained only in a limited number of ED patients requiring intubation. A modified LEMON (Look externally, Evaluate, Mallampati score, Obstruction, Neck mobility) score, when excluding the Mallampati score, is more easily applied to ED patients for prediction of more difficult ET intubation ( Fig. 6.4 ). Additional indicators of a difficult airway include obesity, oropharyngeal edema, hemorrhage, and laryngospasm ( Box 6.1 ). In anticipation of a failed airway, it may be reasonable to mark the cricothyroid membrane using ultrasound guidance to prepare for the possibility of a cricothyrotomy.

Cricothyrotomy is indicated when a difficult airway becomes a “failed airway”. Various algorithms have been designed to define a failed airway. The American Society of Anesthesiologists suggests defining a failed airway as an inability to maintain oxygen saturation greater than 90%, signs of inadequate ventilation (cyanosis, absent breath sounds, hemodynamic instability) with positive pressure bag-mask ventilation, or more than three failed attempts at ET intubation or failure to intubate after 10 minutes by an experienced operator. As more rescue airway adjunctive devices (such as the laryngeal mask airway, gum elastic bougie, or lighted stylet) become available, it is reasonable to continue beyond three attempts at ET intubation if adequate ventilation and oxygen saturation greater than 90% can be maintained.

Because of the anatomic differences between children and adults, including a smaller cricothyroid membrane and a rostral, funnel-shaped, and more compliant pediatric larynx, surgical cricothyrotomy has been contraindicated in infants and young children. The exact age at which surgical cricothyrotomy can be performed is controversial and not well defined. Various textbooks list the lower age limit from 5 years to 10 years or 12 years. The advanced cardiac life support and pediatric advanced life support define an infant airway as age up to 1 year and a child airway as age 1 to 8 years.

Some authors also identify tracheal transection or low tracheal obstruction (below the cricoid) as absolute contraindications to cricothyrotomy because of the need to secure the airway below the injury ( Box 6.2 ).

Equipment

The equipment necessary to perform a traditional surgical cricothyrotomy includes a scalpel with a No. 11 blade, a Trousseau dilator, a tracheal hook, and a tracheostomy tube or modified ET tube (see Review Box 6.1 ). Bent 18-gauge needles may substitute for tracheal hooks. In addition, the sterile tray may include a syringe and lidocaine with epinephrine for local anesthesia, sterile drapes or towels, antiseptic preparation solution, 4 × 4-cm sterile gauze, scissors, hemostats, and suture material. The average adult's cricothyroid membrane is approximately 9 mm longitudinally and 30 mm horizontally. Familiarity with the dimensions of several standard tracheostomy and ET tubes is essential when selecting the appropriate size for surgical airways. Cuffed tracheostomy tubes are recommended, and they come in various sizes. Shiley tracheostomy tubes are commonly available in most EDs. The No. 4 tube has an inner diameter (ID) of 5.0 mm and an outer diameter (OD) of 9.4 mm, and the No. 6 tube has an ID of 6.4 mm and an OD of 10.8 mm. Shiley tracheostomy tubes have three parts: a cuffed outer cannula, a removable inner cannula, and a removable obturator that is solid and removed after insertion ( Fig. 6.5 ). ET tubes are often used temporarily in place of a tracheostomy tube. With respect to ID, ET tube OD can vary with the manufacturer. As an example, the Mallinckrodt TaperGuard Evac Endotracheal Tube with IDs of 6.0 and 8.0 mm have ODs of 9.0 and 11.8 mm, respectively. Although a No. 11 scalpel blade is most commonly used, a No. 20 blade is recommended in some variations of the technique. Commercially available kits include the Melker Cricothyrotomy Kit (Cook Critical Care, Bloomington, IN) for percutaneous cricothyrotomy, which uses the Seldinger technique to insert a cuffed or uncuffed airway catheter.

Procedure

Positioning plays a critical role in success, and the ideal patient position may be impossible because of clinical parameters. For example, hypoxic patients often cannot recline. Ketamine anesthesia does not suppress the respiratory drive and may aid in patient cooperation and positioning. Ketamine is theoretically the superior agent to facilitate the procedure. When feasible, use the supine position with the neck exposed. Unless the patient has a known or suspected cervical spine injury, hyperextend the neck to more readily identify the landmarks. Surgical cricothyrotomy can safely and successfully be performed with minimal cervical spine movement. Preoxygenate the patient by bag-mask ventilation. Prepare the skin of the anterior aspect of the neck with antiseptic solution and create a sterile field with the use of drapes or towels. If the patient is awake or responding to pain, give a subcutaneous and translaryngeal injection of lidocaine with epinephrine as a local anesthetic. Test the integrity of the balloon on the tracheostomy or ET tube by inflating it with 10 mL of air. Wear sterile gloves and take standard precautions by wearing a mask, goggles, and gown. Some preparatory steps may be omitted depending on the urgency of the procedure.