Pediatric Journey - Pediatric Practice Quarterly Newsletter Vol 9 - December 2022 - Stridor and Airway Anomalies

Sep 5, 2026

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Quarterly pediatric newsletter focusing on stridor and airway anomalies, explaining how turbulent airflow in the upper airway produces harsh or musical sounds and why quiet stridor can still signal impending respiratory collapse. Discusses airway dynamics using Poiseuille’s Law and Bernoulli’s Principle to relate airway radius, flow velocity, and intraluminal pressures. Covers key conditions including laryngomalacia, vocal fold immobility (unilateral and bilateral), and the clinical presentation of subglottic stenosis, with emphasis on initial assessment, airway stability, and diagnostic approaches.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages4

Reading Time10 min

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Stridor and Airway Anomalies

Introduction

Airway Dynamics

Laryngomalacia

Vocal Fold Immobility (VFI)

Subglottic Stenosis (SGS)

VOL . 9 DECEMBER, 2022 Quarterly Newsletter of Pediatric Practice at THE PEDIATRIC JOURNEY STRIDOR AND AIRWAY ANOMALIES Jonathan Chiao, MD, MPH PEDIATRIC OTOLARYNGOLOGIST AT EL PASO CHILDREN’S HOSPITAL Introduction: Stridor is characterized as a harsh or musical whistling sound that results from turbulent airflow in a child’s upper airway. When there are obstructive lesions of the airway, the typical laminar airflow pattern becomes disturbed and chaotic. This can be contrasted with stertor which is typically a lower pitched vibratory sound akin to snoring. Turbulent airflow, and thus stridor, can occur during inspiration, expiration, or both – anytime there is air moving in the respiratory system. The initial workup of stridor should be focused on airway stability and assessing the patient’s overall respiratory status and providing support as needed. Loudness of stridor is not indicative of the severity-even quiet stridor can be an ominous sign of impending respiratory collapse as the body tires and the airflow velocity decreases. Airway Dynamics: Poiseuille’s Law (Q = ∆Pπr4 / 8μL) describes the relationship between the flow (Q) of air in the tracheobronchial tree and the cross-sectional radius (r) of the airway. Resistance (1/Q) is therefore inversely proportional to the radius of the airway to the fourth power. A child’s subglottis is the narrowest portion of the upper airway, and small changes in its radius can drastically decrease effective airflow to the lower airways. Bernoulli’s Principle describes the relationship between intraluminal radial airway pressure and flow velocity as air moves through the system. According to Poiseuille’s Law, a narrowed airway will have higher velocity flow and thus by Bernoulli’s Principle will have decreased intraluminal radial pressure to keep the airway patent. Increased flow rate, turbulent flow from luminal collapse, and obstructive lesions all create a turbulent flow pattern that results in stridor. This can occur anytime there is air moving in the respiratory tree – inspiration, expiration, or both. Laryngomalacia: The supraglottis is defined asthe space between the lingual epiglottis and the superior most aspect of the vocal folds. Infants have less rigid cartilage structure of the supraglottic larynx, and increased flow velocity which decreases the transluminal pressures, yielding a higher propensity for collapse. This is exacerbated by feeding, supine position, agitation, and anatomic differences such as short aryepiglottic folds that may tether the epiglottis posteriorly causing supraglottic obstruction of the glottic inlet (Figure 1) . Additionally, redundant mucosa or arytenoid tissue may physically obstruct the inlet causing turbulence and stridor on inspiration. This is diagnosed with awake fiberoptic laryngoscopy and may be performed at bedside or in the office without sedation. This yields a dynamic assessment of the supraglottic airway and is the gold standard for laryngomalacia diagnosis. Symptomatic onset is traditionally described at 2 weeks of age as the child’s respiratory effort increases airway flow velocity, but the physical dimensions of the airway have not substantially increased. This may lead to increased work of breathing, suprasternal tugging, subcostal retractions, and perioral cyanosis. With increased respiratory effort, the caloric expenditure to maintain respiratory homeostasis also increases. Vocal Fold Immobility (VFI): Children may be born with congenital or later acquire unilateral or bilateral vocal fold immobility. This creates glotticlevel obstruction that may present as inspiratory or biphasic stridor. Unilateral VFI is most commonly iatrogenic, but neurologic conditions such as Chiari malformation should also be ruled out. Unilateral VFI is often managed conservatively but requires assessment of the child’s ability to protect their airway during swallow. Aspiration is most common with thin liquids, is often silent without c

FAQs

How should initial workup of a child with stridor prioritize assessment?

Initial workup should focus on airway stability and assessing the child’s overall respiratory status, providing support as needed.

Why is quiet stridor not necessarily less severe?

Loudness does not reliably reflect severity; quiet stridor can still indicate impending respiratory collapse as the body tires and airflow velocity decreases.

How is laryngomalacia diagnosed and what is considered the gold standard?

Laryngomalacia is diagnosed with awake fiberoptic laryngoscopy, which can be performed at bedside or in the office without sedation; it is the gold standard for diagnosis.

Sep 5, 2026

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