23.3.1 What Would Be the Best Way to Manage This Airway?
This patient represents potential difficulties to laryngoscopy and intubation, as well as ventilation with a bag-mask. Cricothyrotomy is possible despite the burn but the open technique is preferred. Despite the difficulties discussed earlier, the extent of the burns, the involvement of the face and neck, and the potential for associated inhalation injury mandate definitive airway management. As stated previously, the fundamental principle is early airway intervention. Any existing difficulties will only become worse with delay.
Anticipating these difficulties, there are a few options possible in this patient. Regardless of the strategy employed, there needs to be a bedside rescue device and surgical airway available before proceeding with any airway management technique. With limited mouth opening and restricted neck movement in the patient described earlier, it is advisable to have a device at the bedside that may be inserted blindly. When mouth opening and neck extension is restricted by loss of skin elasticity, or oral swelling is anticipated, video laryngoscopy may be a preferred alternative to traditional laryngoscopy.
Rescue devices such as the lightwand (Trachlight™), the intubating LMA, the Combitube™, or a rigid fiberoptic laryngoscope, such as the Shikani scope or the Bullard laryngoscope, may be used in this setting. One case report describes the successful use of a Combitube™ in a patient with facial burns, reduced oral opening, and known tracheal stenosis.9 Due to the potential for severe delayed facial edema, the placement of an oral tube is preferred over a nasal approach. However, severe oral swelling from local chemical burns (ingestions, Freon "huffing", etc) may prevent an oral approach, and blind nasotracheal or flexible bronchoscope-assisted nasal intubation may be the only nonsurgical option. Regardless of the intubating technique chosen, an open surgical cricothyrotomy kit should be available at the bedside.
Three approaches may be considered in this patient:
Inspection with the patient awake following topicalization and sedation using a laryngoscope or video laryngoscope. This technique has been well described in other chapters. If assessment suggests that the cords are likely to be visualized, the practitioner may undertake a rapid-sequence induction (RSI) technique. The urgency of the situation may preclude the use of an antisialagogue as it takes 15 to 20 minutes to be effective in enhancing a topical application of local anesthetic agent. A combination of IV midazolam and ketamine would be reasonable choices in this patient. The analgesic properties of ketamine are desirable and the potential for inhalation-induced bronchospasm favor this agent. Pain associated with this injury and respiratory distress may make it difficult to achieve an adequate level of cooperation unless high doses are used. Inability to gain cooperation without compromising ventilation may require the practitioner to move directly to RSI as outlined in option three, later.
Assessment of the airway with a flexible bronchoscope. The technique is similar to that described earlier, including topical anesthesia of the nares. This also requires a level of cooperation that cannot be achieved without sedation and analgesia. Utilizing the flexible bronchoscope, the practitioner may consider intubation over the scope, or proceeding to RSI if assessment suggests this is likely to be successful.
Another option is going directly to RSI. This may be considered if:
Difficulty with laryngoscopy and intubation is not anticipated.
The urgency or uncooperative state of the patient prevents the two options described earlier.
Success was felt to be likely after an awake look.
The RSI procedure should not begin until Plan B and C are prepared and available at the bedside. Plan B should incorporate one of the rescue devices discussed earlier. Plan C should include rapid surgical cricothyrotomy. If difficulties are anticipated but urgency requires RSI, a double setup with the neck prepped and the surgical kit open is recommended. Attendance by another practitioner skilled in cricothyrotomy is desirable. An intubating stylet should be part of the initial laryngoscopic attempt, particularly since the glottic opening may be narrowed or difficult to visualize. Failure of laryngoscopy should be recognized early, allowing no more than three attempts. Persistent laryngoscopic attempts are unlikely to be successful and are associated with adverse outcomes. Instead, be prepared to move rapidly to Plan B or C.
23.3.2 If the Airway Appears Normal on Presentation, Should the Trachea Be Intubated Prophylactically?
As described earlier, not all airway injuries manifest immediately. Edema and associated obstruction will continue for at least 24 hours. Significant generalized edema may progress over several days because of the increased microvascular permeability of all tissues and the significant fluid requirements of burn patients. Tracheal intubation and paralysis may be required to facilitate care such as escharotomies, wound management, associated traumatic injuries, and pain control. If patient transport is required, the initial presentation at the scene or hospital may offer the best conditions for airway management and tracheal intubation, and is strongly encouraged before transportation takes place.3 Even if the upper airway is normal, progression of inhalation injury, particularly in the face of an increased work of breathing, may require tracheal intubation and positive-pressure ventilation. In the care of a burn patient, as a general rule, it is always better to intubate the trachea early than late.
23.3.3 Is Cricothyrotomy Contraindicated in a Patient with Burns Involving the Anterior Neck?
No. In fact there are no absolute contraindications to a surgical airway when the patient cannot be oxygenated and the trachea cannot be intubated, since the alternative is death. Many of these patients have a tracheotomy in their course of treatment (see discussion later), even when burns involve the neck. However, endotracheal intubation is the preferred method of primary airway control. In patients with burns to the anterior neck, elective tracheotomy is generally delayed until 5 to 7 days after skin grafting.10
A cricothyrotomy remains the rescue airway of choice should attempts to secure the airway fail and the trachea cannot be ventilated. In this patient, the significant anterior neck burns have created a noncompliant skin and eschar, obscuring landmarks and causing difficulty with neck extension. An open cricothyrotomy technique using an adequate midline vertical incision, as opposed to a percutaneous Seldinger technique, is therefore recommended in this patient. This will serve as an escharotomy to release the contracted tissue and enhance the ability to identify the cricothyroid space by palpation through the wound.