Acute Laryngotracheobronchitis (Croup)
Upper Airway Viral Subglottic Stenosis
Primary risk age: 6 Months to 3 Years (Peak occurrence)
- Urgency
- Severe
- Typical age
- 6 Months to 3 Years (Peak occurrence)
- Body system
- Respiratory System
Typical course: 3 to 7 days total tracking period.
Reviewed against AAP · CDC · WHO · NHS guidance Last reviewed 2026-06-13
1. Summary & Pathophysiology
Upper Airway Viral Subglottic Stenosis
Pathophysiology (Development Path)
Viral invasion targets the mucosal lining of the larynx and trachea. Localized cellular infiltration results in severe subglottic edema. Because a child's airway is small, any swelling drastically narrows the radius, rapidly increasing airway resistance and causing a harsh inspiratory stridor and barking cough.
Primary Causes & Etiology
Human Parainfluenza Virus Type 1 & 2; Secondary targets include Respiratory Syncytial Virus (RSV) and Adenovirus.
2. Symptom Continuum
- Early Onset Signs
Mild low-grade fever, rhinorrhea, sore throat, clear nasal discharge, and a mild non-productive cough.
- Progressive Phase
Characteristic "barking" or brassy cough, inspiratory stridor developing during agitation, hoarseness, and intercostal retractions.
- Severe Indicators
Continuous inspiratory and expiratory stridor at rest, significant suprasternal and subcostal chest wall indrawing, nasal flaring, lethargy, cyanosis, and asynchronous thoracoabdominal motion.
3. Clinical Verification
Primarily clinical tracking based on stridor qualities and bark dynamics. Plain AP neck X-rays may reveal the diagnostic "steeple sign" due to subglottic narrowing.
4. Care & Elements Plan
Primary Care Treatment Plan
Secure airway patency. Reduce swelling with systemic corticosteroids. Administer nebulized therapies to provide rapid vasoconstriction if distress occurs at rest.
Home Support Elements
Keep child calm to prevent worsening airway resistance. Use cool mist vaporizers or take the child into cool night air to help reduce mucosal congestion.
Generic Active Ingredients (No Brands)
- Dexamethasone (oral or intramuscular active ingredient for systemic inflammation suppression)
- Nebulized Epinephrine (L-epinephrine or racemic formulation for local subglottic vasoconstriction).
Lists active elements only. Never administer self-designed therapies.
5. Doctor Critical Lines
Critical Thresholds: When to See a Doctor
Immediate emergency evaluation is required if the child exhibits stridor at rest, sustained chest wall retractions, inability to swallow clear fluids, or bluish tint around the lips.
6. Vaccine & Prevention
Routine Prophylaxis (Prevention)
Standard respiratory hygiene protocols, including regular hand washing and avoiding close contact with individuals experiencing active upper respiratory infections.
Immunization Context
No specific vaccine targeted directly at the Parainfluenza virus array; up-to-date Influenza coverage is recommended.
7. Timelines & Outlook
Active Timeline
3 to 7 days total tracking period.
Expected Prognosis
Excellent resolution window. Most cases resolve fully within 3 to 7 days without long-term structural airway damage.
Potential Untreated Complications
Hypoxemia, secondary bacterial tracheitis (Staphylococcus aureus vector super-infection), and respiratory failure.
More in Upper Respiratory Track & Airway Dynamic Inflammations
Emergency Acute Epiglottitis
Life-Threatening Upper Airway Supraglottic Cellulitis
2 to 6 Years (Peak occurrence, though rare now due to immunizations)
Moderate Laryngomalacia
Congenital Supraglottic Airway Collapse
Newborns to 18 Months (Typically presents in first few weeks of life)
Mild Common Cold (Viral Nasopharyngitis)
Self-limiting viral upper respiratory tract infection.
All ages; infants and preschoolers average 6–10 colds per year.