19.3.1 What Should We Consider in Managing This Patient's Airway?
This airway is not a crash airway, but it is a difficult one. Difficulty is expected with bag-mask-ventilation and laryngoscopy; the airway is possibly disrupted and neck mobility is limited. Difficulty can also be anticipated with EGD utilization and with cricothyrotomy (potential for hematoma and laryngeal/tracheal distortion).
Summoning help is the first step in the management of this patient. There is time to formulate a plan. The use of paralyzing agents or drugs that might lead to respiratory depression should be avoided in this patient. Conversely, coughing could worsen the injury, or could further compromise a traumatized spinal cord. Careful sedation and topical anesthesia is appropriate in this patient, and in-line stabilization of the cervical spine is an absolute requirement.
Typically, orotracheal intubation should be performed by the most experienced laryngoscopist immediately available. In addition, in-line stabilization of the cervical spine should be employed to guard against exacerbating an unstable cervical injury. Further, in a patient who has a potentially disrupted distal airway, the procedure of choice is intubation using a flexible bronchoscope (FB).11,12 This technique permits visualization as one advances into the trachea and ensures that the endotracheal tube is not advanced into a blind passage. Orotracheal laryngoscopy, following the gentle placement of an Eschmann Introducer (EI) (gum-elastic bougie), may be a distant second choice.1,13 The tactile response transmitted through the EI when it is slid against the tracheal rings may help to confirm that the EI is in the trachea and will guide the ETT into place.14 Confirmation of correct placement with an FB is important, if feasible. A failed airway mandates a tracheotomy.
19.3.2 Step by Step, What Is the Best Way to Intubate the Trachea of This Patient?
Equipment ought to be available to carry out bronchoscopic intubation, orotracheal intubation with an EI, and a tracheotomy. Tracheotomy equipment should be opened at the bedside and the patient's neck should be prepped and anesthetized. A bag-mask-ventilation device, Magill forceps, functioning suction, and airway adjuncts (such as oral and nasal airway devices) should be prepared.
Denitrogenation with a bag-mask-ventilation device is essential. A well-oxygenated patient gives the airway practitioner a cushion of time in the event it is needed. Steadily declining oxygen saturations may mandate assisted ventilation by a bag-mask. It is important to reiterate that EGDs are contraindicated in this patient as they may actually worsen the existing airway distortion. The inability to oxygenate with a bag-mask at any point mandates an immediate surgical airway. Pretreatment with intravenous medications is not indicated in this patient, unless other conditions exist that would mandate their use. Nebulized or atomized 4% lidocaine could be considered for use, provided that adequate denitrogenation can be carried out. Topical anesthesia will help to blunt the protective cough reflex that could aggravate cervical spine injury, or possibly disrupt the patency of a tenuous airway.
Numerous sedating agents may be considered, including ketamine, propofol, midazolam, or etomidate. Ketamine is a good choice for this patient as it carries the benefit of analgesia, along with sedation, with the rare complication of associated laryngospasm, or emergence reaction. Propofol and midazolam may have the advantage of practitioner's familiarity and ease of titration, although both drugs can potentially precipitate complete obstruction through a loss of muscle tone. The advantage of etomidate is its relative cardiovascular stability. However, the potential myoclonus associated with etomidate may place the potential unstable cervical spine and patency of a possible tenuous airway at risk.
Neuromuscular blocking agents ought to be avoided, as suggested earlier, although they may have a role in a crash airway. As mentioned earlier, the FB is the intubation technique of choice for this patient. The amount of time the practitioner has to perform bronchoscopy and intubation will depend on the ability to maintain oxygen saturation. Blood and secretions may make the procedure difficult. In the event a flexible bronchoscope is not readily available, and the patient requires urgent intubation, an oral direct laryngoscopy guided by an EI is a logical alternative. The EI may be gently inserted into the larynx, with the tip of the EI sliding across the tracheal rings to confirm intratracheal placement. However, because of the injury, the trachea may not be contiguous with the larynx. While an awake look may reveal that the glottis can be viewed, this does not guarantee that the trachea is contiguous with the larynx. An inability to visualize glottic structures on the awake look mandates a change of plan and precludes the use of neuromuscular blockade in all but the most extreme circumstances. Further, BURP (backwards, upwards, rightwards pressure) on the larynx may not be possible to do due to the trauma.
Unsuccessful oral intubation after three attempts, oxygen desaturation, or failure in ventilation indicates a failed airway. In this circumstance, tracheotomy is in order. Open tracheotomy is preferable to percutaneous techniques for the reasons stated earlier. This method allows the practitioner to identify the trachea and intubate under direct visualization. Blind attempts at finding the distal airway are rarely successful.15,16