II. Pathophysiology

  1. Turbulent air flow in a partially obstructed upper airway results in a high pitched sound
  2. Location of obstruction determines inspiratory or biphasic timing
    1. Obstruction above the glottis results in Inspiratory Stridor
    2. Obstruction at or immediately below the glottis results in both inspiratory and expiratory Stridor (Biphasic Stridor)
  3. A child's small airways are impacted most significantly by even relatively small partial obstructions (Poiseuille's Law)
    1. Infant: Airway edema of 1 mm reduces a 2 mm radius airway to 1 mm
      1. Resistance to flow increases by 16 fold (Resistance = 1/r^4)
    2. Adult: Airway edema of 1 mm reduces a 5 mm radius airway to 4 mm
      1. Resistance to flow increases by 2-4 fold
  4. Airway Radius By Age at Cricoid Cartilage
    1. Age 0 to 1 year: 3 mm
    2. Age 1 to 2 years: 3.75 mm
    3. Age 2 to 4 years: 4 mm
    4. Age 4 to 5 years: 4.5 mm

III. Epidemiology

  1. Most common in younger children
    1. Airway diameter reduction of 25% results in a cross-sectional airway reduction of 50% (see above)

IV. Precautions

  1. See Awake Nasotracheal Intubation
  2. Maintain airway and consider differential diagnosis
  3. Ready all airway management equipment (RSI, intubation, failed airway)

VI. Causes: Congenital

  1. Choanal Atresia
  2. Maxillofacial dysplasia
  3. Vascular anomalies (e.g. Vascular Ring)
  4. Laryngeal or tracheal abnormalities
  5. Laryngomalacia
  6. Tracheomalacia
  7. Bronchomalacia
  8. Subglottic Stenosis

VIII. Causes: Neoplasm

  1. Airway Papilloma
  2. Airway Hemangioma

IX. Causes: Neurogenic

XI. Causes: Allergy

  1. Spasmodic Croup
  2. Angioneurotic edema

XII. Precautions

  1. Do not distress a child with suspected partial airway obstruction (e.g. croup)
    1. Avoid unnecessary procedures (e.g. delay Intravenous Access until stable)
    2. Position child as they are most comfortable

XIII. Management

  1. Evaluate and treat specific conditions
  2. Emergent management
    1. See Rapid Cardiopulmonary Asessment in Children
    2. See ABC Management
    3. See Respiratory Distress in the Newborn
    4. See Newborn Resuscitation

XIV. References

  1. Dahan, Campbell and Melville (2020) Crit Dec Emerg Med 34(11): 3-10

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Related Studies

Ontology: Stridor (C0038450)

Definition (NCI_CTCAE) A disorder characterized by a high pitched breathing sound due to laryngeal or upper airway obstruction.
Definition (NCI) A symptom resulting from laryngeal obstruction. It is characterized by a high pitched breathing sound.
Concepts Sign or Symptom (T184)
MSH D012135
ICD9 786.1
ICD10 R06.1
SnomedCT 207064008, 158382006, 70407001
LNC LA17612-5
English Stridors, STRIDOR, [D]Stridor (context-dependent category), [D]Stridor, stridor (physical finding), stridor, stridor was observed, stridors, [D]Stridor (situation), Stridulous breathing, Stridor (finding), Stridor
Portuguese ESTRIDOR, Estridor
Spanish ESTRIDOR, [D]estridor (categoría dependiente del contexto), Estridor, [D]estridor, [D]estridor (situación), estridor (hallazgo), estridor, respiración estridulosa
Italian Stridore
Japanese 上気道性喘鳴, ジョウキドウセイゼンメイ
French Stridor, STRIDOR
German Stridor, STRIDOR
Czech Stridor, stridor
Korean 그렁거림
Hungarian Stridor
Norwegian Stridor, Hes piping
Dutch stridor, Stridor