Difficult Airways Secondary to Acute Infectious Causes
Examples of acute infectious processes that alter an otherwise normal anatomy include the following:
Epiglottitis
Croup
Bacterial tracheitis
Retropharyngeal abscess
Ludwig’s angina
Epiglottitis is the classic paradigm for an acute infectious process causing a difficult airway. Although disease incidence has declined dramatically since the introduction of the
Haemophilus influenzae type b (Hib) vaccine, cases continue to be reported secondary to vaccine failures or alternative bacterial etiologies, most commonly gram-positive cocci.
1 Progressive edema and swelling of the epiglottis and surrounding structures can quickly lead to proximal airway obstruction. Despite the rarity of this diagnosis, hospitals should have protocols in place to rapidly summon anesthesia and surgical personnel for any child with a concerning presentation. Agitation of children with epiglottitis can increase turbulent flow and aggravate airway obstruction. Ideally airway evaluation and intervention should occur in the controlled setting of an operating room where equipment and staff are available for rigid bronchoscopy
and surgical airway management as needed. However, if a child deteriorates, attempts at bag-mask ventilation (BMV), direct laryngoscopy and endotracheal intubation may be necessary in the emergency department (ED). If these efforts are unsuccessful, needle cricothyrotomy (see
Chapter 25) can be lifesaving. Epiglottitis represents the prototype indication for an invasive airway, bypassing the proximal obstruction and allowing oxygenation and ventilation through the patent trachea.
Croup is a common reason for children to present to the ED with airway compromise. Although commonly grouped with epiglottitis, croup is usually a clinically distinct entity (see
Table 26-3). Respiratory distress is common, as subglottic airway narrowing can have a profound effect on airway resistance on the smaller diameter trachea in children (see
Table 26-4). However, croup patients are rarely toxic appearing. Fortunately, patients with croup respond well to nebulized epinephrine and steroids, and intubation is rarely required. If patients present in extremis or medical therapy fails, bagging may be difficult given the increased airway resistance, however visualization during laryngoscopy is not usually affected.
Importantly, if a child with croup is ill enough to require intubation, a smaller endotracheal tube (ETT) should be used because the narrowed subglottis may not accommodate age- or length-predicted ETT size. It is important to remember, however, that the ETT insertion distance (i.e., lip-to-tip distance) is not affected despite using a smaller-sized tube. Therefore, while length-based references such as a Broselow-Luten tape will remain accurate, formulaic calculation based on the tube diameter (i.e., three times ETT size) should be based on the age appropriate sized ETT, not the downsized tube.
Bacterial tracheitis has become a leading cause of respiratory failure from acute upper airway infections.
2 As in croup, inflammation in tracheitis is subglottic, although affected children tend to be older and often more ill appearing. Airway management is similar to croup. Again, visualization is rarely compromised; however, a smaller ETT size should be used. In addition, given the presence of thick purulent secretions within the trachea, patients with tracheitis will require vigilant monitoring for tube obstruction.
Retropharyngeal abscess rarely presents with airway compromise, although it is frequently included in the differential diagnosis of acute life-threatening upper airway obstruction. These patients most commonly present with odynophagia and neck stiffness. Lateral neck films reveal thickening of the retropharyngeal space. Most of these patients respond to antibiotics, although in some patients, drainage in the operating room is required. Rarely, if ever, is it necessary to actively manage the airway of these patients in the ED. If the obstruction is large enough to require emergent airway intervention, it is important to remember that placement of an extraglottic device may not be feasible, and alternative backup approaches should be considered.
Ludwig’s angina. is an exceedingly rare pediatric diagnosis and unlikely to require emergency airway management in the ED. If encountered, difficulty with displacement of the tongue into the inflamed submandibular space should be anticipated, and approaches other than direct laryngoscopy should be readily available.
