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The Acute Pediatric Airway


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Key Points

  • 1.

    The assessment of the acute pediatric airway patient includes general appearance (degree of distress), vital signs, skin color, and level of consciousness.

  • 2.

    Stridor is not a diagnosis but rather a symptom or physical sign of turbulent airflow. Localization of the site of turbulence can be guided by the phase(s) of respiration in which stridor is present.

  • 3.

    In general, a rapid onset of airway compromise requires immediate attention, whereas chronic mild stridor without distress can be managed in an outpatient setting.

  • 4.

    Croup is a common viral infection in children. Most cases can be managed conservatively on an outpatient basis; atypical, severe, or recurrent episodes requiring prolonged medical management require further evaluation.

  • 5.

    Always ask about the possibility of foreign body aspiration when evaluating a pediatric patient with acute airway obstruction.

Pearls

  • 1

    The pediatric airway is significantly smaller than the adult airway; inflammation and narrowing of the airway can be far more clinically significant in an infant than a similar degree of edema in an adult.

  • 2

    Multilevel airway obstruction should be considered in children with syndromes.

  • 3

    Bilateral choanal atresia classically presents with respiratory distress and cyanosis at birth that is relieved with crying.

  • 4

    Respiratory distress with inspiratory or biphasic stridor in the setting of a strong cry raises suspicion for bilateral true vocal cord paralysis.

  • 5

    Epiglottitis can frequently be managed nonoperatively with medical management. Younger patients are more likely to require operative intervention.

  • 6

    Urgent intervention is necessary if there is suspicion of button battery ingestion.

Questions

1

How does an infant’s airway differ anatomically from an adult’s?

An infant’s larynx is one-third the size of an adult larynx. The subglottis is the narrowest segment of the pediatric airway compared with the glottis in an adult. The average diameter of a term infant’s subglottis is about 3.5 millimeters compared with 10 to 14 millimeters for an adult.

The neonatal larynx is initially located at vertebral level C2–3, allowing for the supraglottic structures to interdigitate with the soft palate. This protects and optimizes the airway for infant feeding (suck-swallow-breathe pattern). The larynx descends throughout development to level C7 by adulthood.

2

What unique physiologic and mechanical properties of the pediatric airway increase the risk of respiratory compromise in infants versus adults?

The narrow nature of the infant airway makes it much more susceptible to respiratory compromise compared with adults. Poiseuille’s law states that resistance is inversely proportional to the radius to the fourth power. As such, minimal swelling produces significant narrowing of the airway in infants and children. For instance, 1 millimeters of obstruction in the infant subglottis (4 millimeters) leads to a 16-fold increase in resistance and a 75% decrease in airway cross-sectional area. In an adult the same 1 millimeters of obstruction causes only 30% decrease in cross-sectional area and a 2-fold increase in resistance ( Fig. 49.1 ). Additionally, greater chest wall compliance allowing for easier collapse and higher oxygen consumption at baseline, and a smaller lung capacity leads to faster oxygen desaturation in children.

Fig. 49.1, Impact of minimal swelling on the pediatric versus adult airway. According to Poiseuille’s law, resistance is inversely proportional to the radius to the fourth power. A minimal amount of edema in the pediatric airway will have a more significant impact on airway diameter and resistance compared with the same amount of edema in an adult.

3

What is stridor? What is stertor?

Stridor is a harsh, high-pitched noise produced by turbulent airflow in the airway. It can resemble a squeak or whistle. Stridor is not a diagnosis or disease in itself but rather a symptom that indicates narrowing or obstruction of the upper airway. Stertor resembles snoring and indicates nasal or pharyngeal obstruction.

4

Identify the three types of stridor.

Inspiratory stridor reflects airflow impairment above or at the level of the vocal cords. It is generally high pitched when occurring at the vocal cords and may be low pitched (stertor) when obstruction is above the vocal cords (pharynx or supraglottic larynx).

Expiratory stridor is classically caused by obstruction in the distal trachea or bronchi. It gives rise to a more prolonged, sonorous sound and a prolongation of the expiratory phase of respiration.

Biphasic stridor has both an inspiratory and expiratory component and is suggestive of a fixed lesion. This typically suggests a narrowing of the subglottic region, although fixed narrowing in other locations can also result in this sound.

5

What are the signs of impending respiratory failure?

  • Biphasic stridor or quiet breathing after prolonged stridor and increased work of breathing

  • Suprasternal and/or subcostal retractions

  • Abdominal breathing/accessory muscle use

  • Nasal flaring

  • Diaphoresis

  • Mental status changes

  • Neck hyperextension or a “tripod” position (sitting leaning forward with chin up, mouth open, and bracing hands on the bed)

  • Tachypnea, tachycardia

  • Given compensatory mechanisms (tachypnea, tachycardia), oxygen desaturation is a late and ominous sign that frequently indicates impending decompensation

  • Pallor and cyanosis can accompany hypoxia

6

What is the differential diagnosis of respiratory distress that presents immediately at birth?

Airway obstruction that is present at birth is characteristic of a fixed anatomical narrowing of the airway. This can be due to obstruction at the level of the nose, oral cavity/oropharynx, hypopharynx, larynx, or trachea ( Table 49.1 ).

Table 49.1
Differential Diagnosis of Neonatal Airway Obstruction by Anatomic Site
Albert D, Boardman S, Soma M: Evaluation and management of the stridulous child. In: Flint PW, Haughey BH, Lund VJ, et al, eds, Cummings Otolaryngology: Head & Neck Surgery , 5th ed, Philadelphia, 2010, Mosby, table 205-1.
SITE OF OBSTRUCTION DIFFERENTIAL
Nose Rhinitis, piriform aperture stenosis, nasolacrimal duct cyst, nasal mass, choanal atresia, encephalocele or meningocele, midface hypoplasia (Crouzon’s, Down syndrome, etc.)
Oral cavity/oropharynx Micrognathia (Pierre Robin, Treacher Collins, etc.), macroglossia (Down syndrome), lingual thyroid, masses, cysts
Larynx Laryngomalacia, vocal fold paralysis, subglottic stenosis, laryngeal web, laryngeal atresia, cysts or masses
Trachea Tracheomalacia/bronchomalacia, tracheal stenosis or atresia, extrinsic/vascular compression (vascular ring, double aortic arch, pulmonary artery sling, etc.), complete tracheal rings

7

What are the possible causes of neonatal nasal obstruction?

The differential diagnosis includes rhinitis, piriform aperture stenosis, nasolacrimal duct cysts, midline nasal masses, and choanal atresia. Because neonates are obligate nasal breathers until 4 to 6 months of age, the classic presentation of respiratory distress from neonatal nasal obstruction results in difficulty breathing/cyanosis that is relieved with crying.

8

What is choanal atresia?

Choanal atresia is a failure of the posterior nasal cavity to communicate with the nasopharynx, postulated to represent the failure of the nasobuccal membrane to rupture. Two thirds of cases are unilateral and usually present later in life with chronic rhinorrhea and congestion. Bilateral atresia usually presents in the neonatal period with cyanotic events during feeding that are relieved with crying. Fifty percent to 75% of patients will have an associated congenital anomaly.

Suspicion for the diagnosis often arises with respiratory distress at birth and/or with failure to pass catheters through the nose. Diagnosis is made with flexible nasal endoscopy and computed tomography, which is also used for operative planning. Treatment is surgical resection of the atretic plate to create patent choanae.

9

Name a common genetic syndrome with which choanal atresia is associated.

Choanal atresia is a component of the CHARGE syndrome:

  • C = Coloboma

  • H = Heart anomalies

  • A = Atresia of the choanae

  • R = Retardation of growth and development

  • G = Genitourinary disorders (hypoplasia for males)

  • E = Ear anomalies and/or hearing loss

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