Parainfluenza Enters the Laryngotracheal Airway
Placeholder short lead sentence about viral entry into airway epithelium.
- HPIV-1: Common pathogen (placeholder short caption)
- 6mo–3yr: Peak age group (placeholder short caption)
- Fall/Winter: Season (placeholder short caption)
- 2–6 days: Incubation (placeholder short caption)
Viral entry and epithelial spread
Placeholder short paragraph describing viral entry into airway epithelium.
Placeholder highlight callout about early infection stage.
Inflammatory Edema of the Subglottic Mucosa
Placeholder short lead sentence about subglottic inflammation and edema.
- Subglottis: Site of edema (placeholder short caption)
- Cytokines: Mediators (placeholder short caption)
- Loose areolar: Tissue type (placeholder short caption)
- 1–3 days: Onset (placeholder short caption)
Mucosal swelling mechanism
Placeholder short paragraph describing mucosal swelling and vascular leak.
Placeholder highlight callout about edema severity effects.
Steeple-Shaped Subglottic Lumen Narrowing
Placeholder short lead sentence about the classic steeple sign.
- Steeple sign: Imaging sign (placeholder short caption)
- AP neck X-ray: View (placeholder short caption)
- Cricoid ring: Narrowest point (placeholder short caption)
- Up to 80%: Typical narrowing (placeholder short caption)
Lumen geometry and airflow resistance
Placeholder short paragraph describing narrowed lumen and resistance rise.
Placeholder highlight callout about Poiseuille resistance scaling.
Barking Cough from a Narrowed Larynx
Placeholder short lead sentence about barking cough sound origin.
- Seal-like bark: Cough quality (placeholder short caption)
- Subglottic vibration: Sound source (placeholder short caption)
- Low-pitched: Frequency band (placeholder short caption)
- Forced expiration: Trigger (placeholder short caption)
Cough sound generation
Placeholder short paragraph describing barking cough sound generation.
Placeholder highlight callout about cough intensity scaling.
Inspiratory Stridor Appearing at Rest
Placeholder short lead sentence about stridor at rest indicating severity.
- Inspiratory: Sound timing (placeholder short caption)
- Severe sign: Rest stridor (placeholder short caption)
- Turbulent flow: Mechanism (placeholder short caption)
- Westley score: Score tool (placeholder short caption)
Stridor as a severity marker
Placeholder short paragraph describing stridor at rest as severe marker.
Placeholder highlight callout about escalation to severe croup.