48 Chronic Pediatric Airway Disease

Question 1

List the three most common congenital disorders of the larynx.

Answer 1

List the three most common congenital disorders of the larynx.

In order of most to least common: laryngomalacia, vocal cord paralysis, subglottic stenosis.

Question 2

What is stridor?

Answer 2

What is stridor?

Stridor is an audible breath sound due to turbulent airflow from airway narrowing.

Question 3

What is the most common cause of stridor in the neonate and infant?

Answer 3

What is the most common cause of stridor in the neonate and infant?

Laryngomalacia.

Question 4

Describe the characteristics of laryngomalacia.

Answer 4

Describe the characteristics of laryngomalacia.

There are several theories regarding the etiology of laryngomalacia, including anatomic changes resulting in short folds of tissue between the epiglottis and arytenoids as well as neuromuscular control of the supraglottis. Inspiratory stridor occurs with collapse of the supraglottic tissue on inspiration. Affected infants typically present with intermittent inspiratory stridor within the first two weeks of life. Stridor is usually worse with feeding, while supine, or while agitated. The child may need to take breaks while feeding to breathe. The majority of cases are self-limited, with resolution of symptoms by age 18 months. However, approximately 10% of patients will experience significant upper airway obstruction resulting in feeding difficulties, failure to thrive, pectus excavatum, apneic episodes, cyanosis, and hypoxia. These patients warrant consideration for surgical intervention.

Patients may have associated gastroesophageal reflux disease (GERD). This condition may contribute to airway edema, further compromising the airway. Acid suppression may improve mild cases of laryngomalacia and is often instituted empirically.
Diagnosis is made with awake flexible fiber-optic laryngoscopy, which allows for rapid diagnosis without need for anesthesia.

Question 5

What is the typical size of the pediatric airway?

Answer 5

What is the typical size of the pediatric airway?

Airway size is determined based on the narrowest portion of the airway. In the pediatric population, this site is the subglottis at the level of the cricoid cartilage. In a term infant, the subglottic lumen measures 4.5 to 5.5 mm.

Question 6

How is an endotracheal tube size chosen?

Answer 6

How is an endotracheal tube size chosen?

Endotracheal and tracheostomy tube sizes are based on the inner diameter of the tube. For example a 4.0 endotracheal or tracheostomy tube correlates to an inner diameter of 4 mm. The smallest tube that provides adequate ventilation should be chosen. Several size-predictive formulas exist and are based on parameters such as age, height, weight, and/or finger width. One commonly used formula is based on the age of the patient: inner diameter = 4 + age/4. This formula is more accurate for older children.

Question 7

Describe the characteristics of subglottic stenosis.

Answer 7

Describe the characteristics of subglottic stenosis.

Subglottic stenosis (SGS) is narrowing of the subglottis and can be either congenital or acquired. Congenital SGS occurs in the absence of a history of endotracheal intubation or other causes of acquired stenosis. Causes of congenital SGS include an elliptical cricoid, congenital narrowing (as in Down syndrome), and trapped first tracheal ring.

Acquired stenosis is more common than congenital SGS. Endotracheal intubation is the most common acquired cause. Duration of intubation and endotracheal tube size are the two most important factors in the development of stenosis. Stenosis occurs as a result of pressure necrosis and subsequent scar formation. Prevention of subglottic stenosis via selection of the proper endotracheal tube and a short duration of intubation is ideal. Other causes include neck trauma, laryngeal procedures, caustic ingestions, radiotherapy, and tracheal infection. Diagnosis is made at the time of direct laryngoscopy and bronchoscopy.

Question 8

Describe the most commonly used grading system for subglottic stenosis.

Answer 8

Describe the most commonly used grading system for subglottic stenosis.

The Myer-Cotton classification system is the most widely used system for grading the degree and severity of subglottic stenosis (Figure 48-1).

Question 9

How is subglottic stenosis treated?

Answer 9

How is subglottic stenosis treated?

Surgical methods of managing subglottic stenosis include endoscopic and open transcervical techniques. Choice of method depends on many patient factors including degree of stenosis, comorbid conditions, and age of the lesion. Thin weblike lesions that are identified early, when the scar is immature, may be amenable to endoscopic procedures including scar lysis by balloon dilation. More mature, thicker lesions with greater superior-inferior dimension may require augmentation or resection procedures. Augmentation procedures involve placing cartilage grafts into the airway to make the lumen bigger. Resection procedures involve removing the affected segment and anastomosing the airway.

Question 10

What is the underlying embryologic defect that leads to the development of a laryngeal cleft?

Answer 10

What is the underlying embryologic defect that leads to the development of a laryngeal cleft?

The tracheoesophageal septum forms from two opposing ridges in the midline of the primordial aerodigestive tract into what will eventually become the larynx/trachea and the esophagus. The septum forms in a caudal to cranial direction. Laryngeal clefts are a result of incomplete development and fusion of the tracheoesophageal septum resulting in an abnormal communication between the airway and the hypopharynx/esophagus.

Question 11

Describe the most commonly used classification system for laryngeal clefts.

Answer 11

Describe the most commonly used classification system for laryngeal clefts.

The Benjamin-Inglis system is the most commonly used classification system (Figure 48-2).

Figure text: Type 1: The cleft is isolated to the supraglottic interarytenoid region located above or at the level of the vocal cords. Type 2: The cleft extends into the upper portion of the cricoid but not through the inferior border. Type 3: The cleft extends through the inferior border of the cricoid cartilage, can variably extend into the cervical trachea. Type 4: The cleft extends into the thoracic trachea and may extend to the carina.

Question 12

Discuss the typical presentation of laryngeal clefts.

Answer 12

Discuss the typical presentation of laryngeal clefts.

The presentation of this anomaly depends on the severity of the defect. For type I and certain type II laryngeal clefts, symptoms may be subtle and include hoarse voice, mild stridor, chronic cough, lingering upper respiratory infections, and recurrent pneumonia. Because the presentation may be subtle, a high index of suspicion is needed to make the diagnosis. More severe types of laryngeal clefts present at birth with respiratory distress and aspiration with po intake.

Question 13

Which syndromes are associated with laryngeal cleft?

Answer 13

Which syndromes are associated with laryngeal cleft?

See Table 48-1.

Question 14

What is the most common cause of unilateral vocal cord paralysis?

Answer 14

What is the most common cause of unilateral vocal cord paralysis?

Iatrogenic complications are the leading cause of unilateral vocal fold paralysis with patent ductus arteriosus (PDA) ligation resulting in left vocal cord paralysis being the most frequent cause. The incidence of iatrogenic vocal cord paralysis has increased as the number of pediatric cardiothoracic procedures has increased. Other surgical procedures that can lead to unilateral vocal fold paralysis include repair of tracheoesophageal fistulas and esophageal atresia repair. Birth trauma may also result in vocal cord paralysis.
Unilateral vocal cord paralysis also may be congenital in origin. Arnold Chiari malformations can lead to vocal cord paralysis but are classically thought to cause bilateral rather than unilateral paralysis. Other less commonly encountered causes of unilateral paralysis include neoplasms of the central nervous system, neck, or mediastinum causing recurrent laryngeal nerve dysfunction.

Question 15

Describe the clinical course of unilateral vocal cord paralysis.

Answer 15

Describe the clinical course of unilateral vocal cord paralysis.

Unilateral vocal cord paralysis presents with stridor, a weak cry, and feeding difficulty with possible aspiration. This condition is the second most common cause of stridor in the infant. The diagnosis is made with an awake, flexible fiber-optic laryngoscopy. Further workup may be needed in patients in whom an underlying cause is not apparent (idiopathic). Imaging the course of the recurrent laryngeal nerve from skull base to mediastinum may be performed to identify potential etiologies. Patients with difficulty feeding may benefit from evaluation for aspiration via modified barium swallow or fiber-optic endoscopic evaluation of swallowing.

Seventy percent of idiopathic causes of unilateral vocal cord paralysis are expected to resolve spontaneously, most within 6 months of age. Cases of iatrogenic paralysis are less likely to resolve, with 35% of patients noted to recover function at 16-month follow-up. For those patients who are severely symptomatic, vocal cord medialization may improve speech and swallow function at the cost of increasing airway narrowing at the glottis and stridor.

Question 16

What is an infantile hemangioma?

Answer 16

What is an infantile hemangioma?

Infantile hemangiomas are benign vascular neoplasms that develop during infancy as a result of disordered angiogenesis. These lesions may occur throughout the body but are most commonly found within the head and neck, including the airway. Symptoms and signs are dependent on the location and natural history of the hemangioma. These are the most common tumors of infancy.

Question 17

What signs and symptoms could indicate the presence of an airway hemangioma?

Answer 17

What signs and symptoms could indicate the presence of an airway hemangioma?

Infantile hemangiomas of the airway present in early infancy during the rapid proliferative phase with symptoms of progressive airway compromise. Patients may present with biphasic stridor or a chronic cough which may be misdiagnosed as croup. Failure to respond to standard treatment should lead to consultation with ENT. A particularly high degree of suspicion is warranted in the stridulous child with cutaneous hemangiomas of the lower face. Up to 50% of patients with cutaneous hemangiomas within a beard distribution will have a synchronous airway lesion. Diagnosis of an airway hemangioma is made on fiber-optic laryngoscopy and/or direct laryngoscopy in the operating room. Plain films of the neck may reveal an asymmetric narrowing of the subglottis as well.

Question 18

What is the standard treatment of a subglottic infantile hemangioma?

Answer 18

What is the standard treatment of a subglottic infantile hemangioma?

While many infantile hemangiomas do not require treatment, those in the airway and in particular those in the subglottis warrant therapy. Medical therapy includes oral systemic steroids and propranolol. Steroids aim to stop angiogenesis and decrease surrounding inflammation and swelling. Systemic steroid treatment, however, is only effective in the proliferative phase. Multiple studies have documented rapid regression of hemangiomas with the use of propranolol. The exact mechanism to explain the effect of propranolol on hemangiomas has not been identified.

Surgical therapy is an option for those patients who are not adequately treated with medical therapy alone. Endoscopic treatment includes laser treatment and steroid injection into the lesion. In addition, the lesion may be excised via open transcervical approach. Finally, tracheostomy may be needed in certain patients in order to bypass the site of obstruction in the subglottis until spontaneous involution occurs.

Question 19

What is tracheomalacia?

Answer 19

What is tracheomalacia?

Tracheomalacia is softness/collapsibility of the trachea. It is diagnosed during rigid or flexible bronchoscopy when there is greater than 50% loss of airway diameter during coughing. Lateral chest x-rays during inspiratory and expiratory phases may also demonstrate collapsibility of the tracheal airway. Tracheomalacia presents as expiratory stridor (sometimes biphasic), barky cough, and prolonged or recurrent pulmonary infections. This condition may be classified as extrinsic or intrinsic.

Intrinsic tracheomalacia occurs if the tracheal cartilage is weak or absent. The majority of children with intrinsic tracheomalacia outgrow the condition during the first few years of life. Management for these children includes the potential need for early intervention for pulmonary illnesses, inhaled steroids for airway edema, and the understanding that the barky cough is not necessarily croup. A condition commonly associated with intrinsic tracheomalacia is tracheoesophageal fistula.

Extrinsic tracheomalacia implies that a structure outside of the airway is compressing the tracheal cartilage. This is most commonly related to cardiac and vascular anomalies (i.e., vascular rings which may encircle the airway). A barium esophagram may suggest a vascular ring encircling the airway. Rigid bronchoscopy and CT or MRI are also diagnostic of vascular ring.

Question 20

What is recurrent respiratory papillomatosis?

Answer 20

What is recurrent respiratory papillomatosis?

Recurrent respiratory papillomatosis (RRP) is a neoplasm of the airway that is caused by human papilloma virus (HPV). It is the most common benign neoplasm of the pediatric larynx, leading to symptoms of dysphonia and stridor. This disease does occur in adults and tends to be less aggressive.

Question 21

What are the most common types of HPV that lead to RRP?

Answer 21

What are the most common types of HPV that lead to RRP?

HPV types 6 and 11 are the most common HPV types that lead to RRP. Specific viral types are associated with disease severity. For example, HPV 11 subtype has been associated with more airway obstruction, tracheal disease, pulmonary disease, and need for tracheostomy.

Question 22

How is RRP transmitted?

Answer 22

How is RRP transmitted?

Vertical transmission via contact through an infected birth canal is the proposed method of disease transmission from mother to child. It has been suggested that newly acquired genital lesions are more likely to shed viral particles, which is thought to account for the higher incidence of disease in patients born to young mothers of low socioeconomic status. However, the overall risk of contracting RRP from a mother with active genital condylomata at the time of birth is generally low (1 in 231 to 400). Cesarean section is then likely of limited use to prevent vertical transmission, especially given the risks and significant costs associated with the procedure. The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists do not currently recommend cesarean section to solely protect the neonate from HPV infection.

Question 23

List the risks factors for the development of RRP.

Answer 23

List the risks factors for the development of RRP.

• First born child
• Teenage mother
• Vaginal delivery (it should be noted that several cases exhibit in utero transmission)

Question 24

How is RRP treated?

Answer 24

How is RRP treated?

There is no single treatment modality that has been shown to eradicate RRP once and for all. The current mainstay of therapy is surgical reduction of disease burden (to debulk as much disease as possible while maintaining normal morphology and anatomy). Methods include cold steel excision with or without powered instrumentation (e.g., microdebrider) versus laser excision (carbon dioxide, potassium titanium phosphate (KTP)).

Adjuvant medical treatments also exist, though none have demonstrated efficacy in double blind, randomized controlled trials. The most well-known adjuvant therapy is topical injection of the antiviral medication cidofovir. There are multiple statements from the RRP Task Force regarding counseling on and potential use of cidofovir as an option.

Question 25

How is RRP prevented?

Answer 25

How is RRP prevented?

HPV vaccination is likely the most important mode of prevention. There are currently multiple vaccines in development and one commercially available FDA-approved vaccine. Gardasil is a quadrivalent HPV vaccine which addresses HPV subtypes 6, 11, 16, and 18.

Question 26

Define aspiration. How does it differ from penetration?

Answer 26

Define aspiration. How does it differ from penetration?

Aspiration occurs when a material passes from the upper airway below the true vocal cords. Alternatively, penetration occurs when a material passes into the larynx but not past the true vocal cords. Penetration deep into the larynx is a risk factor for aspiration.

Question 27

List the four phases of swallowing.

Answer 27

List the four phases of swallowing.

See Table 48-2.

Question 28

How do abnormalities of the phases of swallowing contribute to aspiration?

Answer 28

How do abnormalities of the phases of swallowing contribute to aspiration?

Any abnormality, whether anatomic or functional, of any phase of swallowing can contribute to swallowing dysfunction and ultimately result in aspiration. Dysfunction can be broken down into the affected phase of swallowing. For example, vocal cord paralysis can result in abnormal glottic closure during the pharyngeal phase of swallowing and possible aspiration. Neurologic disorders, on the other hand, can result in muscular weakness and dysfunction of any phase of swallowing.

Question 29

What are anatomic abnormalities that may predispose a pediatric patient to aspiration?

Answer 29

What are anatomic abnormalities that may predispose a pediatric patient to aspiration?

Cleft palate, tracheoesophageal fistula, laryngeal cleft, macroglossia, and micrognathia are all examples of anatomic abnormalities of the head and neck that can lead to dysfunctional swallow and aspiration.

It is important to note that neurologic conditions, hypotonia, and certain syndromes (e.g., Down syndrome) are highly associated with aspiration during oral intake. Providers should keep this in mind when caring for these select patient populations.

Question 30

Discuss the workup of suspected pediatric aspiration.

Answer 30

Discuss the workup of suspected pediatric aspiration.

Evaluation for aspiration includes obtaining a history consistent with aspiration (coughing and choking with feeds, recurrent pneumonia, wheezing, respiratory distress, etc.) as well as supportive radiographic or endoscopic testing. Modified barium swallow studies (MBS) are used to evaluate the oral cavity, pharynx, and upper esophagus during swallowing. During MBS, different consistencies of barium preparations are given to the patient during fluoroscopy of the upper aerodigestive tract. Penetration and aspiration with different consistencies may be noted and recommendations regarding safe oral intake can be made.
Flexible or fiber-optic endoscopic evaluation of swallowing (FEES) is an additional method of evaluating the airway during oral intake. FEES relies on the direct visualization of swallow via a nasopharyngeal fiber-optic examination. During the examination, the patient is asked to swallow foods of varying consistency. MBS and FEES each have their strengths and weaknesses as tools for the evaluation of aspiration. Patients may undergo both exams in order to gain the greatest amount of information regarding their disease process.