Chapter 19. Airway Management with Blunt Anterior Neck Trauma

A 25-year-old man drives into an unseen wire while he is snowmobiling. The wire strikes his anterior neck and throws him from his snowmobile. Paramedics failed to place an endotracheal tube (ETT) in the field and he arrives in the emergency department (ED) immobilized on a long spine board, with a cervical collar in place. He is unconscious, unresponsive to painful stimuli, and with stridor. Initial vital signs include a heart rate of 120 beats per minute (bpm), a blood pressure of 160/90 mm Hg, a respiratory rate of 24 breaths per minute, and an oxygen saturation of 93% on room air. A non-rebreather oxygen mask is applied, and his oxygen saturation increases to 97%.

Palpation demonstrates no obvious subcutaneous air, but there is a large abrasion across the anterior and lateral areas of the neck (Figure 19-1). Palpation of the larynx demonstrates crepitus and slight anatomic distortion. Plans begin immediately to protect and secure the airway.

19.2.1 What Are the Important Considerations in Evaluating This Patient?

Upon arrival at the ED, the team should follow a protocol that is consistent with the guidelines of the Subcommittee of Advanced Trauma Life Support® of the American College of Surgeons Committee on Trauma.1 Aggressive initial management and a high index of suspicion for associated injuries are key steps in the successful management of patients with this type of injury.

A young patient with no significant medical history should have adequate cardiorespiratory reserve. His initial oxygen saturation is concerning, but it improves with supplemental oxygen. His depressed level of consciousness could be due to a number of factors, and anoxic injury to the brain or spinal cord must be a consideration. His normotension, elevated pulse rate, and use of accessory muscles of respiration would suggest that his cervical cord is essentially intact. Despite two small studies which suggest that laryngotracheal injury is compatible with a normal cervical spine,2,3 the airway practitioner must assume that this patient has a cervical spine fracture until proven otherwise.4

Other associated injuries can occur with this type of clothesline injury. These include facial laceration, laceration of the esophagus, and injury to the recurrent laryngeal nerve.5 It is imperative to thoroughly evaluate the patient after first ensuring airway, breathing, and circulation.

19.2.2 What Are the Airway Priorities in This Patient?

Considerations in this patient include laryngeal fracture, tracheal disruption, and a hematoma which could impinge on the airway; all of these may be difficult to detect.6 Blunt anterior neck trauma can influence all four choices of initial airway management in this patient: bag-mask-ventilation, use of the extraglottic devices (EGDs), laryngoscopy and intubation, and cricothyrotomy.

Difficulty with bag-mask-ventilation could stem from either anatomical upper airway distortion due to the trauma itself, tracheal disruption, or to trauma related to prior intubation attempts. Unfortunately, the use of EGDs may be contraindicated in the setting of supraglottic or glottic disruption, or distortion.7,8

Anticipate difficult laryngoscopy. Supraglottic or glottic distortion may hinder visualization of the vocal cords. In the event the practitioner elects to pursue direct laryngoscopy, a Miller blade may be the preferable blade, as it may provide better control of the epiglottis and a more direct line-of-sight vision.9

One must recognize that blunt anterior airway trauma may result in disruption of the trachea distal to the glottis. Tracheal transection may result in obstruction to tube passage or placement of the tube in a false passage through the tracheal disruption. Orotracheal laryngoscopy cannot detect this injury and may lead to a false sense of security relative to the ease of intubation.10 One case series demonstrated six of seven tracheal disruptions to be at the cricothyroid/tracheal junction; four of these seven were successfully intubated while the others required emergency tracheotomy.10

Cricothyrotomy may be very difficult in laryngeal trauma, as normal anatomic landmarks may be distorted, making it difficult to identify the larynx, the cricothyroid membrane, and the cricoid ring. In addition, subcutaneous air may compromise the capacity to identify the trachea to perform percutaneous needle puncture and for this reason, an open surgical technique is the preferred surgical approach (see Chapter 13 for details).

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

19.4.1 What Are the Concerns with Ventilation and Postintubation Care?

Once intubated, confirmation of ventilatory exchange takes priority. The presence of end-tidal CO2 indicates that the ETT is in the trachea and that the lower respiratory tree is being ventilated. Care must be taken to secure the ETT in place. Sedation is in order, as continued protection of the cervical spine until fracture, dislocation, and ligamentous disruption of the cervical spine have been ruled out. Paralysis may also be in order if this patient is endangering his spine by excessive movement.

19.4.2 What Are Potential Postsurgical Complications Associated with Clothesline Injuries?

The outcome is generally very good if the patient survives the initial injury, and receives prompt aggressive resuscitation and airway management.16 However, following the repair of the laryngotracheal and cervical spine injuries, several serious postoperative complications may occur. These include: mediastinal infection; tracheoesophageal fistula; and subglottic stenosis.5 In a retrospective review of clothesline injury in children and adolescents (on all-terrain vehicles), between 1998 and 2003, Graham et al reported that all patients (n= 7) had significant neck and/or facial lacerations, with long-lasting disfigurement.17 One of the patients also had a functional impairment.

19.4.3 What Other Alternative Should Be Considered If Securing the Airway Is Not Possible for a Patient with a Clothesline Injury?

Extracorporal circulation via a femoral-femoral cardiopulmonary bypass (CPB), placed with the use of local anesthesia and a portable unit, can be a lifesaving method of oxygenation and could have an important role in managing patients with a severely disrupted trachea. This can provide a safe solution for oxygenation when tracheal intubation or a surgical airway is either unsuccessful or too hazardous. However, a review of the literature did not reveal the use of CPB in airway compromise from clothesline injury. Furthermore, establishment of a femoral-femoral bypass requires at least 15 to 20 minutes, even in experienced hands,18 making it impractical and difficult to apply in emergency situations.

In summary, blunt anterior neck injury poses a unique challenge to airway management. Care must be taken to protect airway reflexes whenever an inability to intubate is anticipated. The airway practitioner must recognize many barriers to airway management which can prevent intubation, including an obstructing hematoma or a transected trachea. Intubation using a flexible bronchoscope is the ideal method of intubation in these patients, as the indirect visualization provides the reassurance that the trachea is contiguous.