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Croup (Laryngotracheobronchitis)

Basics

  • Infection causing inflammation/edema of larynx and subglottic airway
  • Presents with barking cough, inspiratory stridor, hoarseness, and respiratory distress
  • Usually viral; spasmodic croup is recurrent, often without viral prodrome
  • Most common airway obstruction cause in young children

Epidemiology

  • Age: 6 months to 3 years, peak at 18 months; rare outside 3 months to 6-7 years
  • Male predominance
  • Seasonal peak: fall and early winter but can occur year-round
  • Incidence: 1.3% of ED cases; 3-7% require hospitalization; <3% require airway intervention
  • 4.4% return ED within 48 hours

Etiology and Pathophysiology

  • Viral causes:
  • Parainfluenza virus types 1 & 2 (>80%)
  • RSV, influenza A/B, adenovirus, rhinovirus, enteroviruses, measles (unvaccinated), metapneumovirus
  • Bacterial causes (less common): Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis
  • Spasmodic croup: unclear etiology; possibly allergy, airway hyperreactivity, reflux
  • Congenital subglottic stenosis may present as recurrent croup
  • Narrow pediatric airway + negative inspiratory pressure → airway narrowing and stridor

Risk Factors

  • Prior intubations, airway abnormalities, prematurity, age <3 years

Prevention

  • Spread via droplets; contagious up to 3 days after illness onset or until afebrile
  • Influenza vaccination may reduce risk
  • Hand hygiene important

Associated Conditions

  • Possible future asthma association with hospitalization for croup
  • Consider anatomical or allergic causes if recurrent
  • COVID-19 may cause atypical or severe croup

Diagnosis

  • Clinical diagnosis: abrupt onset barking cough, inspiratory stridor, hoarseness, chest wall indrawing
  • Fever usually low-moderate; absence does not exclude croup
  • Severity signs: nasal flaring, retractions, tripoding, tachypnea; late signs include cyanosis, fatigue
  • Westley Croup Severity Score for assessment (≤2 mild; 3-7 moderate; 8-11 severe; ≥12 respiratory failure)
  • SARS-CoV-2 testing if severe or prolonged

Physical Exam

  • Tachypnea, tachycardia common
  • Pulse oximetry usually normal unless severe
  • Stridor at rest, aggravated by agitation
  • Hoarseness present
  • Decreased breath sounds or signs of respiratory failure = concern

Differential Diagnosis

  • Foreign body aspiration
  • Bacterial tracheitis (high fever, rapid worsening)
  • Retropharyngeal/peritonsillar abscess
  • Allergic reactions/angioedema
  • Epiglottitis (rare post-Hib vaccination)
  • Anatomic anomalies (tracheomalacia, subglottic stenosis)
  • COVID-19 related severe croup

Diagnostic Tests

  • Usually clinical; labs not routinely needed
  • WBC mild lymphocytosis; bandemia suggests bacterial infection
  • Imaging not routine; neck films show "steeple sign" (40-60%) but nonspecific
  • Imaging and laryngoscopy reserved for atypical cases or suspicion of alternative diagnoses

Treatment

General Measures

  • Supportive care; minimize agitation to reduce distress
  • Oxygen for hypoxia or distress
  • Frequent clinical monitoring
  • Heliox may be used but evidence limited

Medications

  • Corticosteroids for all severity levels; dexamethasone preferred 0.6 mg/kg PO/IM/IV (max 16 mg)
  • Nebulized epinephrine for moderate to severe (Westley ≥3) cases:
  • Racemic epinephrine 0.05 mL/kg of 2.25% (max 0.5 mL)
  • L-epinephrine 0.5 mL/kg of 1:1000 (max 5 mL)
  • Observe 2 hours post-epinephrine for rebound
  • Avoid antitussives and decongestants
  • Antibiotics only if bacterial infection suspected
  • Humidified air has no proven benefit

Surgery/Procedures

  • Intubation rare; use smaller size tube (0.5–1 mm smaller)
  • Indicated for respiratory failure or fatigue from work of breathing

Admission and Nursing

  • Admit if poor response to treatment, recurrent stridor after epinephrine, oxygen requirement, pneumonia, or other serious conditions
  • Discharge criteria:
  • ≥2 hours since last epinephrine dose
  • Received steroids
  • No stridor at rest or breathing difficulty
  • Tolerating oral fluids
  • Normal color, air entry, and consciousness
  • Established home care and follow-up

Ongoing Care

  • Diet: cool liquids, small frequent feedings
  • Educate on illness course, avoid agitation, hydration, hand hygiene
  • Seek emergency care for cyanosis, lethargy, drooling, severe respiratory distress
  • COVID-19 croup may require quarantine guidance

Prognosis

  • Generally good with supportive care
  • Severe cases respond to intensive management
  • Recurrence rare; if frequent, investigate other causes

Complications

  • Subglottic stenosis (post-intubation)
  • Bacterial tracheitis
  • Cardiopulmonary arrest
  • Pneumonia

ICD10: - J05.0 Acute obstructive laryngitis [croup] - J20.9 Acute bronchitis, unspecified - J38.5 Laryngeal spasm

Clinical Pearls: - Most common in fall/winter, children 6 months to 3 years - Inspiratory stridor is hallmark and should raise suspicion - Nighttime symptoms common - Prioritize clinical diagnosis and management over labs/imaging - Recurrence warrants further evaluation - Consider alternate diagnoses in toxic or atypical presentations - Decreasing noise or air movement can signal respiratory failure - Corticosteroids are mainstay; oxygen and epinephrine for moderate-severe cases