47 Acute Pediatric Airway

Question 1

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

Answer 1

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

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

Question 2

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

Answer 2

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

In smaller airways, minimal swelling can produce a significant narrowing of the airway. This is because of Poisuelle’s law, which states that resistance is inversely proportional to the radius to the fourth power. As such, 1 mm of obstruction in the infant subglottis (4 mm) leads to a 16-fold increase in resistance and a 75% decrease in airway cross-section compared to the same obstruction in an adult airway (12 mm), which only causes a 30% decrease in cross-sectional area and a 2-fold increase in resistance (Figure 47-1). Additionally, quicker oxygen desaturations occurs in children due to a greater chest wall compliance allowing easier collapse, a higher oxygen consumption at baseline, and a smaller lung capacity.

Figure text: 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 to the same amount of edema in an adult.

Question 3

What is stridor? What is stertor?

Answer 3

What is stridor? What is stertor?

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

Question 4

Identify the three types of stridor.

Answer 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, though fixed narrowing in other locations can also result in this sound.

Question 5

What are the signs of impending respiratory failure?

Answer 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

Question 6

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

Answer 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, and trachea (Table 47-1).

Question 7

What are the possible causes of neonatal nasal obstruction?

Answer 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.

Question 8

What is choanal atresia?

Answer 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.
Diagnosis is made by failure to pass catheters through the nose and confirmed with flexible endoscopy and CT scan. Treatment is surgical resection of the atretic plate to create patent choanae.

Question 9

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

Answer 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

Question 10

What is Robin sequence?

What are other causes of obstruction at the same level?

Answer 10

What is Robin sequence? What are other causes of obstruction at the same level?

Robin sequence (RS) describes a triad of micrognathia, glossoptosis, and airway obstruction. Glossoptosis and retrognathia result in obstruction at the level of the base of tongue and oropharynx. Micrognathia and glossoptosis can prevent fusion of palatal shelves at the midline, resulting in a U-shaped cleft palate.
RS can occur in isolation or with a syndrome (Treacher Collins, Stickler, velocardiofacial syndrome, and many others). Presence of a syndrome with mandibular hypoplasia should raise suspicion for multilevel obstruction.

Question 11

Discuss the evaluation and management of children with Robin sequence.

Answer 11

Discuss the evaluation and management of children with Robin sequence.

In addition to a complete history and physical, flexible fiber-optic/rigid laryngoscopy, bronchoscopy, sleep endoscopy, and polysomnogram are commonly used to characterize the degree of obstruction.
Many cases of RS can be managed with supplemental oxygen, prone positioning, placement of a nasopharyngeal trumpet, and/or continuous positive airway pressure (CPAP). Failure to thrive, obstructive sleep apnea, and respiratory failure require escalation of management.

Definitive surgical management options include tongue-lip adhesion, mandibular distraction, and tracheostomy.

Question 12

Name four congenital laryngeal anomalies that cause respiratory distress.

Answer 12

Name four congenital laryngeal anomalies that cause respiratory distress.

• Laryngomalacia (most common)
• Collapse of the supraglottic larynx resulting in inspiratory stridor
• May result from aryepiglottic fold shortening, redundant supraglottic tissue, and/or hypotonia
• Vocal fold paralysis
• Congenital subglottic stenosis
• Congenital laryngeal web

Question 13

What is the cause of bilateral vocal fold paralysis (BVCP)?

Answer 13

What is the cause of bilateral vocal fold paralysis (BVCP)?

Bilateral vocal cord paralysis is most commonly idiopathic (46%). Other causes include Arnold Chiari malformation, cerebral palsy, hydrocephalus, spina bifida, birth trauma or hypoxia. Workup consists of an MRI of the brain to evaluate for intracranial abnormalities, genetic consultation to evaluate for chromosomal abnormalities, and laryngoscopy with palpation of the cricoarytenoid joint to delineate BVCP from joint fixation.

Question 14

How does bilateral vocal fold paralysis present and how is it managed?

Answer 14

How does bilateral vocal fold paralysis present and how is it managed?

Patients typically present at birth with respiratory distress and inspiratory or biphasic stridor. Flexible fiber-optic laryngoscopy should be performed to evaluate supraglottic architecture and cord mobility. The mainstay of treatment is tracheotomy; most cases of idiopathic BVCP demonstrate recovery of function in time, and decannulation is often possible.

Question 15

How do infections of the different divisions of the larynx differ in presentation?

Which pathogens are most commonly associated with each?

Answer 15

How do infections of the different divisions of the larynx differ in presentation? Which pathogens are most commonly associated with each?

See Table 47-2.

Question 16

What radiographic findings are classically found in supraglottitis, croup and bacterial tracheitis?

Answer 16

What radiographic findings are classically found in supraglottitis, croup and bacterial tracheitis?

• Supraglottitis: “Thumb sign” on lateral neck x-ray
• Thickening and rounding of the epiglottis with loss of the normal air space of the vallecula
• Croup: “Steeple sign” on AP neck x-ray
• Narrowing at the level of the subglottis
• Bacterial tracheitis: “Pseudomembranes” on lateral neck x-ray
• Ratty or irregular tracheal borders indicative of thick, purulent secretions or sloughing mucosa

Figure text: Imaging characteristics of pediatric airway infections. A, Supraglottitis. Rounded epiglottis (white arrow), thickened aryepiglottic folds (white arrowheads), and distention of the hypopharyngeal space. B, Croup. Narrowed subglottis (black arrows), showing a “steeple sign.” C, Bacterial tracheitis. Tracheal lumen obscured by sloughed mucosa (black arrows). Note normal epiglottis (black arrowhead). D, Retropharyngeal abscess. Widened retropharyngeal soft tissues compared to the vertebral bodies.

Question 17

What is another name for supraglottitis?

Describe the change in incidence in the last several decades.

Answer 17

What is another name for supraglottitis? Describe the change in incidence in the last several decades.

Epiglottitis is another name for supraglottitis, but this is somewhat inaccurate because this clinical entity typically involves the entire supraglottis. Most cases of supraglottitis were due to hemophilus influenza type b (HIB), the incidence of which has dropped dramatically since implementation of the HIB vaccine in 1988.

Question 18

Discuss the presentation and management of supraglottitis.

Answer 18

Discuss the presentation and management of supraglottitis.

Patients with supraglottitis most commonly present with odynophagia (pain with swallowing), dysphagia (difficulty swallowing), voice change (muffled voice, hoarseness), and difficulty tolerating secretions. Stridor and respiratory distress are less common signs, but suggest an impending surgical emergency. The “tripod” positioning of the patient is associated with respiratory distress.
Management consists of close airway surveillance with possible operative intervention to establish an airway. Parents are counseled that intervention spans a wide spectrum from direct laryngoscopy or fiber-optic endotracheal intubation to placement of a tracheotomy; however, in most cases, this is not necessary. Airway intervention is more common in younger patients, with a mean of 4 years of age (almost two thirds are 2 years old or younger). Anxiety-provoking maneuvers should be avoided when handling a patient with a tenuous airway; all instrumentation and interventions should be performed in the operative suite.
If operative intervention is necessary, direct laryngoscopy should be performed after the airway is secured to obtain swab cultures from the epiglottis and evaluate for an abscess at the lingual surface of the epiglottis. Intravenous antibiotics should be started and a 10- to 14-day course should be completed. Extubation can generally be accomplished within 48 hours when supraglottic edema improves and an air leak is present around the endotracheal tube.

Question 19

How is croup managed?

Answer 19

How is croup managed?

Croup is very common; 3% to 5% of all children have one episode in their lifetime. Most cases can be managed conservatively with supportive care only. For more significant symptoms, corticosteroids have been shown to decrease hospitalization rate and severity of disease. Generally one dose of dexamethasone is sufficient and nebulized racemic epinephrine can also be used to decrease airway edema. Between 85% and 99% of patients can be managed as outpatients. Hospitalized patients should be treated with repeated doses of intravenous dexamethasone and racemic epinephrine until symptoms resolve. Only 1% to 5% of patients require intubation for severe airway obstruction.
Direct laryngoscopy should be considered in very young children or those with recurrent or severe croup to rule out underlying airway pathology (i.e., subglottic stenosis, hemangioma, subglottic cyst, etc).

Question 20

How is bacterial tracheitis managed?

Answer 20

How is bacterial tracheitis managed?

Though severity of symptoms is usually not as dramatic as in acute epiglottitis, airway obstruction is not infrequent with bacterial tracheitis and management includes rigid bronchoscopy with debridement of secretions. About 60% to 80% require intubation and repeated endoscopies can be performed for recurrent plugging and crusting. Extubation can be achieved after fevers resolve, secretions diminish, and an air leak is present around the endotracheal tube. Intravenous antibiotics are directed toward Staphylococcus aureus for a 10- to 14-day course.

Question 21

Describe how pharyngeal infections can lead to airway obstruction.

Answer 21

Describe how pharyngeal infections can lead to airway obstruction.

Peritonsillar, parapharyngeal, and retropharyngeal abscesses can all present with airway obstruction and require surgical drainage for management. Peritonsillar abscesses present with a “hot potato” voice and stertor, as the level of obstruction is at the oropharynx. Airway symptoms are usually milder than with parapharyngeal and retropharyngeal abscesses. Parapharyngeal and retropharyngeal abscesses present with fevers, sore throat, dysphagia, and decreased neck mobility and should be considered in the differential diagnosis of croup and bacterial tracheitis. Airway obstruction is more likely and severe with retropharyngeal abscesses. Management of the airway should be carefully planned in patients with large abscesses. Care should be taken with sedation because endotracheal intubation can be challenging or even impossible and the airway can be lost. Tracheostomy may have to be considered. See Figure 47-2, panel D.

Question 22

When evaluating a pediatric patient with acute airway obstruction, what should always be included in the history of present illness?

Answer 22

When evaluating a pediatric patient with acute airway obstruction, what should always be included in the history of present illness?

Always ask if there is concern for or possibility of foreign body (FB) aspiration. About half of aspiration events are not witnessed. If the foreign body does not immediately cause airway obstruction, symptoms can be more subtle and mimic other airway infections, asthma, or pneumonia. A high index of suspicion should be maintained for FB aspiration and history regarding possible aspiration events should always be included when working up children with airway symptoms.

Question 23

What are risk factors for foreign body aspiration?

Answer 23

What are risk factors for foreign body aspiration?

FB aspiration is most common in toddlers between 1 and 3 years of age. This is because they are more likely to explore their environment with their mouths, they have poor coordination of swallowing, they lack posterior dentition necessary for chewing food properly, they lack an appreciation of what is edible, and they are likely to be playing while eating. Other risk factors include male gender and developmental delay or neurologic impairment.

Question 24

Which items have the highest risk for aspiration?

Answer 24

Which items have the highest risk for aspiration?

Toddlers are most likely aspirate or ingest incompletely chewed food, most commonly nuts, seeds, and beans. Other common objects include small plastic or metal toys or pieces. Coins are the most common esophageal foreign bodies.

Question 25

What are the symptoms of foreign body aspiration?

Answer 25

What are the symptoms of foreign body aspiration?

Symptoms vary depending on the location of the foreign body and how long it has been present.

• Larynx: FB in the larynx can cause an airway emergency requiring emergent intervention. Patients can present with obstruction, cough, and hoarseness. Delay in diagnosis can allow edema to progress and cause a partial obstruction to become a complete obstruction.
• Trachea: Symptoms include stridor, wheezing, dyspnea, and coughing. Hoarseness is absent in comparison to laryngeal FB.
• Bronchi: This is the most common location for airway FB to lodge (80% to 90%). The classic triad of cough, wheeze, and decreased unilateral breath sounds may not always be present, but nearly all patients will have at least one of these symptoms.
• Esophagus: Dysphagia, odynophagia, drooling, and vomiting are common symptoms of esophageal foreign bodies. Esophageal FB are more common than airway FB. Common sites of esophageal FB are at the cricopharyngeus and at the level where the esophagus crosses the aortic arch.

Question 26

What is the x-ray of choice in diagnosis for airway foreign bodies?

Answer 26

What is the x-ray of choice in diagnosis for airway foreign bodies?

Inspiratory and expiratory chest films. As the lodged FB can cause air to enter but not escape, air trapping or hyperinflation can be appreciated on x-ray and exaggerated by the expiratory phase. Other changes seen on plain films include atelectasis and pneumonia. Radiopaque objects and those in the bronchi are more likely to be detected on x-ray. A negative film should not rule out FB aspiration, as between 25% and 50% of patients can have completely normal radiographs.

Question 27

What is the management of foreign body aspiration?

Which situations require urgent intervention?

Answer 27

What is the management of foreign body aspiration? Which situations require urgent intervention?

Management includes direct laryngoscopy and bronchoscopy for evaluation and endoscopic removal of the foreign body. Intubation and treatment with steroids are considered for those patients with severe obstruction, mucosal damage, or significant airway edema. Bronchial foreign bodies can result in postobstructive pneumonia distal to the point of obstruction. Always consider evaluation of the esophagus when a child presents with airway obstruction or a positive history and has a normal bronchoscopy because esophageal foreign bodies can cause effacement of the airway. Coins in the esophagus have a high rate of passage through the GI tract and watchful waiting can be considered in older children and those in the distal esophagus when there are no signs of airway compromise.
Urgent intervention is necessary for acute or potential airway obstruction, concern for esophageal injury, or suspicion of disc battery ingestion.

Question 28

Discuss button battery ingestion and describe the differences in management compared with ingested coins.

Answer 28

Discuss button battery ingestion and describe the differences in management compared with ingested coins.

A button battery can be mistaken for a coin, but will often have a characteristic “double halo” or “double ring” sign on AP view or may have a step off on lateral view.

The incidence of button battery ingestion has remained relatively stable (about 10 to 12 per million per year), but there has been a dramatic rise in complications and fatalities over the past 10 years as more household objects utilize batteries and battery size has increased. Though hearing aid batteries are the most commonly ingested battery, they are smaller, pass more easily, and pose less of a risk of serious injury to the aerodigestive tract.

Urgent intervention is indicated because button batteries can begin to cause mucosal damage due to caustic injury within 1 hour and esophageal perforation can occur within 6 hours. Twelve percent of young children who ingest batteries greater than 20 mm in diameter will experience a major complication, such as perforation, tracheoesophageal fistula, major vessel injury, esophageal stricture, vocal cord paralysis, or cervical spine injury.