The Difficult Pediatric Airway

OVERVIEW

Age-related anatomic and physiologic differences in the normal infant or small child can make airway management challenging. However, these differences can be anticipated and addressed in most pediatric patients as discussed in Chapter 24. The difficult pediatric airway, as in adults, is defined by historical or physical examination attributes that predict challenges with mask ventilation, laryngoscopy, or intubation. In the pediatric population, most of these cases result either from acute insults that modify normal airway anatomy or from known congenital abnormalities. Difficulty related to unpredictable anatomic abnormalities revealed only after unsuccessful attempts at airway management, resulting in a failed pediatric airway, is rare in children.

The approach to the emergent difficult airway in the adult patient is described in Chapters 2 and 3, which should be read before this chapter. The same concepts of anticipation and planning are also applicable in children. The use of rapid, easy-to-remember, and sensitive tools to identify patients with potential difficulty is paramount. Children differ from adults, however, with regard to which predictors of difficulty are most common (see Table 26-1). For example, age-dependent features (e.g., beards and age > 55 years) and progressive disease processes (e.g., cervical rheumatoid arthritis) are less applicable in children. However, using LEMON to prompt recognition of abnormal facial features and assessing for signs of obstructive airway disease will be of high yield (see Table 26-2). The majority of children with difficult airways will present with recognizable disease processes or with known congenital abnormalities associated with airway difficulty. Therefore, this chapter will focus on these common etiologies of difficult pediatric airways and offer management strategies. Table 26-3 offers a general approach to the management of both normal and difficult pediatric airways.

TABLE

26-1

A Sample Comparison of Pediatric and Adult Risk Factors

A. Risk factors for adult difficult airway usually not present in infants and young children:

1. Obesity

2. Decreased neck mobility (excluding immobilization following trauma)

3. Teeth abnormalities

4. Temporomandibular joint problems

5. Beards

B. Risk factors for pediatric difficult airway not present in adults:

1. Small airway caliber susceptible to obstruction from edema or infection

2. Discomfort secondary to dealing with age- and size-related variables

3. Discomfort secondary to infrequency of patient encounters

TABLE

26-2

Key Features in Applying the LEMON Assessment in Children

Look	■ Gestalt is the most important predictor of airway difficulty in children ■ Presence of dysmorphic features is associated with abnormal airway anatomy and may predict difficulty ■ Small mouth, large tongue, recessed chin, and major facial trauma are usually immediately apparent
Evaluate (3:3:2)	■ Has not been tested in children ■ May be difficult to perform in an uncooperative child, or infant with a “pudgy” neck ■ Gross assessment of mouth opening, jaw size, and larynx position may be utilized instead ■ If 3:3:2 assessment is performed, use the child’s, not the provider’s fingers
Mallampati	■ Cooperation may be an issue ■ Mixed data in children (see “Evidence” section)
Obstruction Obesity	■ Airway obstruction is a relatively frequent indication for airway management in children ■ Second to the gestalt Look, assessing for obstruction is perhaps the most fruitful step in identifying difficulty airways in children ■ A focused, disease-specific history and physical examination (voice change, drooling, stridor, and retractions) can accurately identify children with acute or chronic upper airway obstructive pathology ■ Obesity is a growing epidemic in children, although the impact on the pediatric airway is less significant than in adults
Neck	■ Limited positioning in immobilized pediatric trauma patients is similar to that in adults ■ Intrinsic cervical spine immobility from congenital abnormalities is very rare, and acquired conditions (e.g., ankylosing spondylitis and cervical rheumatoid arthritis) are essentially nonexistent in young children

TABLE

26-3

General Approach to the Pediatric Airway Normal versus Difficult

The “Awake” Sedated look The determination of whether a given patient has a normal or difficult airway is a subjective clinical decision that guides which equipment will need to be utilized to secure the airway. When the clinical assessment is uncertain, the clinician can administer 2 mg/kg of ketamine, which produces a state of dissociation while maintaining respiratory effort that allows the clinician to insert a laryngoscope and assess whether glottic opening visualization is feasible or not, thus guiding the appropriate method of intervention.
Anticipated “normal” airway
Condition
Prerespiratory Failure	■ Non-rebreather ■ Noninvasive ventilation
Respiratory Failure—Immediate and/or Transient	■ Bag-mask ventilation^a
Respiratory Failure	■ Rapid sequence intubation ■ Direct or video laryngoscopy
Anticipated/unexpected “difficult” airway
Cannot Intubate, Can Ventilate^b	■ Extraglottic device ■ Video laryngoscopy
Cannot Intubate, Cannot Ventilate	■ “Surgical” airway (needle, Seldinger, or open)

^aMay be useful as temporizing measure with airway obstruction

^bMay include dysmorphic features

COMMON CAUSES OF DIFFICULT AIRWAYS IN CHILDREN

Causes of difficult airways in children can be categorized into four groups:

1. Acute infectious causes

2. Acute noninfectious causes

3. Congenital anomalies

4. No known abnormality, with unexpected difficulty

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. Progressive edema and swelling of the epiglottis and surrounding structures can quickly lead to proximal airway obstruction. Because the diagnosis is uncommon and the management is challenging, hospitals should promote protocols that allow emergency physicians, anesthesiologists, and surgical personnel to work quickly and collaboratively to construct an airway plan for any child with a concerning presentation. Agitating a child with epiglottitis can increase turbulent airflow 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 a cardinal 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 a clinically distinct entity (see Table 26-4). 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 26-5). 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 edematous subglottis will be narrowed and 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

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