Table of Contents
Definition
Croup is an acute viral inflammatory disease of the upper airway involving the larynx, trachea, and bronchi, leading to subglottic edema and airway obstruction.
Epidemiology
- Age: 6 months – 3 years (can occur up to 6 years)
- Male > Female
- Peak: Autumn & early winter
- Usually preceded by URTI
Etiology
Viral (most common)
- Parainfluenza virus type 1 (most common)
- Parainfluenza 2 & 3
- RSV
- Influenza A & B
- Adenovirus
- Human metapneumovirus
Rare bacterial causes
- Mycoplasma
- Secondary bacterial infection (uncommon)
Pathophysiology
- Viral infection → inflammation & edema of subglottic region
- Subglottis is the narrowest part of pediatric airway
- Small edema → marked increase in airway resistance
- Leads to inspiratory stridor & respiratory distress
Clinical Features
Prodrome
- Low-grade fever
- Coryza
- Cough
Characteristic features
- Barking (seal-like) cough
- Hoarseness
- Inspiratory stridor
- Worse at night
- Aggravated by crying & agitation
Severe disease
- Stridor at rest
- Chest retractions
- Tachypnea
- Hypoxia
- Fatigue / altered sensorium (late sign)
Severity Assessment (Westley Croup Score – concept)
| Feature | Mild | Moderate | Severe |
|---|---|---|---|
| Stridor | None / with agitation | At rest | Loud, biphasic |
| Retractions | None | Mild–moderate | Severe |
| Air entry | Normal | Decreased | Markedly reduced |
| Cyanosis | None | None | Present |
| Mental status | Normal | Normal | Altered |
Investigations
- Diagnosis is clinical
- No routine labs required
- Neck X-ray (AP) (only if diagnosis unclear):
- Steeple sign (subglottic narrowing)
⚠️ Avoid throat examination if severe obstruction suspected.
Differential Diagnosis
| Condition | Key Differentiating Feature |
|---|---|
| Epiglottitis | High fever, drooling, muffled voice |
| Bacterial tracheitis | Toxic child, high fever |
| Foreign body | Sudden onset, no prodrome |
| Retropharyngeal abscess | Neck stiffness, drooling |
| Angioedema | Facial/lip swelling |
Management
General Measures
- Keep child calm
- Minimal handling
- Oxygen if hypoxic
- Humidified air (comfort measure only)
Pharmacological Treatment
1️⃣ Corticosteroids (All cases)
Dexamethasone (Dexona)
- Dose: 0.6 mg/kg
- Max: 10 mg
- Route: Oral / IM / IV
- Single dose usually sufficient
2️⃣ Adrenaline Nebulization (Moderate–Severe)
L-Adrenaline (1:1000)
- Dose: 0.5 mL/kg (max 5 mL)
- Dilute with NS to 5 mL
- Rapid onset (10–15 min)
- Duration: ~2 hours
⚠️ Observe 2–4 hours after neb (rebound stridor)
Indications for Admission
- Stridor at rest
- Need for repeated adrenaline
- Hypoxia
- Poor oral intake
- Age < 6 months
- Social concerns
Indications for ICU / Intubation
- Exhaustion
- Altered consciousness
- Severe hypoxia
- Poor air entry
- Failure to respond to treatment
Complications
- Respiratory failure
- Secondary bacterial infection
- Pneumonia
- Rarely death
Prognosis
- Excellent
- Self-limiting (3–7 days)
- Recurrence possible
Key Takeaway
- Single dose dexamethasone for all croup
- Adrenaline = temporary relief
- Steeple sign = croup
- Drooling → think epiglottitis
- Avoid agitation at all costs
