Novel role of focused airway ultrasound in early airway assessment of suspected laryngeal trauma

Laryngeal injuries are often undiagnosed in the initial evaluation of the trauma patient. They are rare, with an estimated incidence of one in every 30,000 emergency department admissions [1]. Delayed recognition and intervention may prove fatal in the presence of upper airway obstruction [2].

Blunt laryngeal trauma may present with varying degrees of severity, from mild to life-threatening extremes. A tracheostomy may be required to gain airway access distal to the site of injury. A systematic classification and management approach of blunt laryngeal trauma is crucial to guide early decision-making and improve patient outcome in the emergency department.

Current standard of care for laryngeal trauma is determined according to the Schaefer classification of laryngeal injury. Schaefer group 1 and group 2 with minor endolaryngeal injuries can be managed conservatively with observation, antibiotics, steroids, voice rest and anti-reflux medications. However, for more severe Schaefer type 3–5 injuries, open surgical repair will be required to secure a definitive airway [1, 2].

Good history taking, detailed clinical examination and a high index of suspicion are critical in the diagnosis of laryngeal trauma. The diagnosis can be aided using flexible nasendoscopy by direct visualization of the airway. CT scanning of the neck is still considered the gold standard to grade the severity of the injury and to direct appropriate management. Obtaining a timely CT scan may often be challenging due to logistical problems, primarily availability of radiology service support especially in resource-limited area, and stability for patient transfer.

Of late, studies have integrated the use of upper airway ultrasound into point-of-care ultrasound examination, a paradigm shift in upper airway assessment [3‐5]. The incorporation of ultrasound into the diagnostic arm may expedite the intervention process by removing some logistics problem and provide rapid information to guide timely management.

We discuss the role of focused airway ultrasound in upper airway trauma performed by point-of-care ultrasound trained emergency physician and propose a focused airway ultrasound classification in relation to Schaefer classification of laryngeal injury.

The ABCs of trauma, a mantra that prioritizes the primary survey starts, with “A” for airway. In this case series, we describe four encounters in which ultrasound of the upper airway was performed for suspected laryngeal trauma and correlated with CT scan assessment of severity based on the Schaefer classification of laryngeal injury.

Upper airway obstruction as a consequence of laryngeal injury may be catastrophic. Apart from blunt force trauma, iatrogenic injuries can occur after percutaneous dilatational tracheostomy, fiberoptic bronchoscopy, airway manipulations and procedures, even tracheal intubation [6, 7, 8]. The lack of correlation between symptoms, physical findings and severity of laryngeal injury may result in delayed recognition of such injuries. Additionally, patients with laryngeal injury are at risk of false passages, transforming an incomplete fracture to total separation of the upper airway, converting mild upper airway obstruction to complete obstruction especially in undiagnosed laryngeal trauma [9‐11]. For these reasons upper airway ultrasound may play an important role in the early assessment for laryngeal injury.

For the past three decades the internationally accepted Schaefer classification of laryngeal injury stratification system has been used to categorize laryngeal injury. This classification not only categorizes, but it also guides management. It divides the management plan into 2 categories; non-invasive or conservative airway management for group 1 and group 2 injuries, and invasive airway management for higher grade injuries (group 3 to group 5). Further study is needed to determine if focused upper airway ultrasound can reliably be used to determine injury grade [1].

While the authors could not find previous publication of ultrasound assessment for upper airway injury in trauma, prior research by Osman et al. and You-Ten et al. briefly illustrated the usage of airway ultrasound in a step-by step manner to delineate the normal sonoanatomy of the upper airway such as thyroid cartilage, epiglottis, cricoid cartilage, cricothyroid membrane, tracheal cartilages, esophagus and the surrounding soft tissues [3‐5]. Schick et al. published promising evidence on the use of airway ultrasound in the emergency setting to identify airway edema and impending threats to the airway [12]. Airway ultrasound can also be used to assess laryngeal edema in the post-extubation period. [13‐15]. Kameda et al. [16] identified airway edema as hypoechoic thickening of the tracheal wall on airway ultrasound in a patient with inhalational burns. The findings on the sonogram were later confirmed by CT scan, demonstrating good correlation between focused ultrasound and CT Scan.

Cheng et al. [17] found good correlation between sonographic visualization of abnormal vocal cords movement and laryngoscopic examination. They demonstrated that clinician-performed airway ultrasound is an accurate screening tool for preoperative assessment of vocal cord movement.

Upper airway ultrasound findings that correlate with the Schaefer Classification System may be especially relevant in hemodynamically unstable patients where CT imaging is not feasible. While larger trials are needed, we propose that focused airway ultrasound can be used to correlate with the Schaefer Classification System (Table 1) and therefore propose it be assimilated into the work-up of laryngeal trauma.

Possible advantages of focused upper airway ultrasound in the diagnostic classification of blunt laryngeal trauma are:

Ultrasound assessment of the upper airway is a promising adjunct in the rapid evaluation of patients with suspected laryngeal trauma. Early diagnosis and injury classification stratification with point-of-care ultrasound may play an important role in trauma patient care, particularly those too unstable for CT imaging or when advanced imaging is unavailable.