return to: Pediatric Airway
see also: The Evaluation of Stridor in Pediatric Patients and Pediatric Airway Sizing (password protected)
Note: last updated before 2013
General
- Defined as the inward collapse of the supraglottic structures during inspiration, leading to partial occlusion of the airway.
- Laryngomalacia is the most common cause of stridor in pediatric patients
- Responsible for 65-75% of cases of stridor
- The exact cause of laryngomalacia is still unknown and is an area of great interest, however, it is thought to be caused by a combination of three factors:
- Redundant tissue in above the vocal folds
- Decreased neuromuscular control of the supportive cartilaginous structures of the airway
- Supraglottic edema due to laryngeal inflammation
- Most cases of laryngomalacia resolve by 18-24 months, however, 10% will present with severe features requiring surgical intervention
Epidemiology
- Laryngomalacia is the most common congenital abnormality of the larynx and the most common cause of stridor in pediatric patients
- In a study of 205 pediatric patients presenting with the primary concern of stridor:
- Laryngomalacia was the cause in 75% of cases. (BLANK)
- In a study of 205 pediatric patients presenting with the primary concern of stridor:
- Males are 2x as likely to have laryngomalacia than females
- Premature infants have a greater propensity to have poor neuromuscular control of the airway and are at increased risk
Anatomy
- The epiglottis is formed from the 3rd and 4th branchial arches.
- Overgrowth of the 3rd branchial arch structures leads to redundant tissue in the supraglottis.
- Contrary to previous belief, patients with laryngomalacia do not have "soft cartilage."
- Histologic studies of the cartilage in patients with laryngomalacia are indistinct when compared to patients without laryngomalacia.
Pathophysiology
- Redundant tissue present in the supraglottis collapses to obstruct the airway during inspiration
- Decreased area of the airway leads to increased resistance to air flow
- Airway resistance is inversely proportional to the radius of the airway by a power of four.
- The velocity of the air increases as it passes the site of obstruction via the Venturi effect
- This increase in velocity creates a low-pressure vacuum at the site of obstruction, leading to further airway collapse via the Bernoulli Principal
- Gastroesophageal Reflux Disorder (GERD) is commonly seen in patients with laryngomalacia
- 65-100% of patients with laryngomalacia also have GERD
- Reflux and continued irritation of the laryngeal structures leads to tissue edema and further airway obstruction.
- The velocity of the air increases as it passes the site of obstruction via the Venturi effect
- This increase in velocity creates a low-pressure vacuum at the site of obstruction, leading to further airway collapse via the Bernoulli Principal
- Gastroesophageal Reflux Disorder (GERD) is commonly seen in patients with laryngomalacia
- 65-100% of patients with laryngomalacia also have GERD
- Reflux and continued irritation of the laryngeal structures leads to tissue edema and further airway obstruction.
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Proposed Mechanism of Laryngomalacia
Classification:
- Type I: Prolapse of the mucosa overlying the arytenoid cartilages
- Type II: Foreshortened aryepiglottic folds
- Type III: Posterior displacement of the epiglottis
(Olney, et al. The Laryngoscope 1999. Used with permission from John Wiley and Sons)
Clinical Presentation
- The most common presenting symptom in laryngomalacia is inspiratory stridor.
- Symptoms typically start during the first few weeks of life and resolve by 18-24 months of age.
- Parents may report that the stridor is increased when the child is:
- Supine
- Feeding
- Agitated
- Crying
- Infants may present with feeding difficulties such as:
- Regurgitation, coughing, choking, and slow feedings.
Physical Exam
- The first step in evaluation of any patient with stridor is to assess for signs of respiratory collapse:
- Cyanosis
- Intercostal, subxyphoid, and supraclavicular contractions
- Nasal flaring
- Marked agitation
- Assess the timing of stridor with the respiratory cycle
- Inspiratory stridor is classically associated with supraglottic pathology (such as laryngomalacia)
- Expiratory stridor is associated with subglottic pathology
- Biphasic stridor is seen in "fixed airway lesions", typically at the level of the vocal folds.
- Evaluate for failure to thrive (weight for age that falls below the 5th percentile and/or weight deceleration that crosses two major percentile lines on the growth chart)
- Often due to difficulties with feeding and/or increased energy expenditure due to increased work of breathing.
Diagnostic Testing
Flexible Fiberoptic Laryngoscopy
- Laryngomalacia is best diagnosed via flexible fiberoptic laryngoscopy in an awake patient
- Sedation can promote the collapse of supraglottic structures, leading to a greater number of false-positives
- Flexible fiberoptic laryngoscopy may demonstrate:
- Elongation and lateral extension of the epiglottis that collapses posteroinferiorly during inspiration
- Redundant arytenoids that collapse anteromedially during inspiration
- Shortening of the aryepiglottic folds, which leads to tethering of the arytenoids to the epiglottis
- Inward collapse of the aryepiglottic folds during inspiration
- The vocal cords demonstrate appropriate function and mobility
- Up to 19% of patients with laryngomalacia will have additional synchronous lesions of the airway
- Some investigators mandate direct laryngoscopy and bronchoscopy to identify these potentially life-threatening lesions.
Direct Laryngoscopy
- Patients presenting with "severe features" should undergo direct laryngoscopy.
- Severe features include (Smith):
- Severe respiratory distress
- Failure to thrive
- Recurrent pneumonia
- Infants with symptoms that do not match their exam with FFL
- Synchronous lesions of the airway
- Patients with laryngomalacia requiring surgical intervention
Imaging
Flexible fiberoptic laryngoscopy demonstrating classic 'omega-shaped' epiglottis in a patient suspected for laryngomalacia
(Image property of Wikimedia Commons - released to public domain)
Management
- The management of laryngomalacia depends on the severity of airway obstruction
- Most cases resolve without surgical intervention by 18-24 months (90%).
Medical Management
- Children with laryngomalacia should be serially assessed to ensure adequate weight gain.
- Airway collapse during feeding can lead to feeding difficulties and food aversion.
- Chronically increased work of breathing can dramatically increase calorie consumption, especially in a newborn.
- Treatment of GERD
- Use of weight-adjusted PPIs or H2 blockers reduces airway inflammation and edema:
- Eg: omeprazole 0.7 mg/kg/dose once daily or ranitidine 3 mg/kg 3 times a day
- Note that PPIs should not be used in premature infants until >40 weeks of age due to an increased risk for necrotizing enterocolitis (NEC).
- Encourage upright feeding and bottles that minimize aerophagia to decrease the occurrence of reflux.
- Providing small, frequent feedings and/or thickening of formula can decrease reflux symptoms.
- 24 hour pH and impedance studies may be useful in assessing management in infants with refractory reflux symptoms despite maximum acid suppression dosing.
- Use of weight-adjusted PPIs or H2 blockers reduces airway inflammation and edema:
Surgical Management
Surgical management is indicated in cases of airway compromise or in cases with severe features such as:
- Life-threatening airway obstruction
- Refractory hypoxia/apneic episodes
- Recurrent cyanosis
- Cor pulmonale/pulmonary hypertension
- Failure to thrive
References
Daniel R. Olney; John H. Greinwald, Jr., MD; Richard J. H. Smith, MD; Nancy M. Bauman, MD. Laryngomalacia and its Treatment. The Laryngoscope. November 1999.