Recurrent Croup

Recurrent croup is repeated episodes of acute barking cough, stridor and hoarseness, usually defined as 2 or 3 or more episodes in a year, or episodes beyond the usual age of 6 months to 6 years. It may represent spasmodic croup or an underlying airway abnormality.

Acute viral croup affects about 3% of children, mostly at 6 months to 3 years, and recurrence is common, with about 5 to 6% having several episodes. Recurrent or severe episodes, particularly with onset in the first year of life, suggest structural narrowing.

Causes include subglottic stenosis, tracheomalacia, laryngeal cleft, subglottic haemangioma, vascular ring, laryngeal papillomatosis, gastro oesophageal reflux, eosinophilic disease, atopy and foreign body.

Pathophysiology.

Viral infection (parainfluenza virus most commonly) causes subglottic mucosal oedema, and the subglottis is the narrowest part of the child airway. A fixed narrowing greatly increases resistance, so even mild oedema produces stridor.

In spasmodic croup, allergy, reflux and airway hyper-responsiveness are suspected, and episodes are typically sudden at night without fever.

• Barking cough, hoarse voice and inspiratory stridor, worse at night and with crying, often after a mild upper respiratory illness.
• Retractions, tachypnoea, agitation and cyanosis in severe episodes.
• Between episodes the child may have persistent noisy breathing, history of intubation, feeding difficulty or reflux.

Red flags.

• Onset under 6 months, stridor at rest between episodes, or failure to thrive.
• Previous prolonged intubation, congenital anomalies, or cutaneous haemangiomas (subglottic haemangioma).
• More than 3 episodes in a year, severe episodes, or poor response to treatment.
• Drooling, high fever or toxic appearance, suggesting epiglottitis, bacterial tracheitis or foreign body.

• Clinical diagnosis of acute episodes. Assess severity by stridor at rest, retractions, oxygen saturation and level of consciousness.
• Airway endoscopy (flexible laryngoscopy and rigid or flexible bronchoscopy under general anaesthetic) in children with recurrent, severe, atypical or early onset episodes, to look for subglottic stenosis, haemangioma, malacia, cleft or papillomas.
• Reflux assessment (pH-impedance monitoring), allergy testing, and neck and chest radiographs or CT for vascular ring.
• Swallow assessment when aspiration is suspected.

Differential diagnosis. Subglottic stenosis, tracheomalacia, laryngomalacia, vocal cord palsy, subglottic haemangioma, bacterial tracheitis, epiglottitis, foreign body, retropharyngeal abscess, anaphylaxis and angioedema.

Acute episode.

• Dexamethasone 0.15 mg/kg orally as a single dose (up to 0.6 mg/kg for severe croup, maximum 16 mg). Prednisolone 1 mg/kg is an alternative.
• Nebulised adrenaline 1 in 1000 (1 mg/mL) 0.5 mL/kg (maximum 5 mL) for stridor at rest, repeated after 20 to 30 minutes if needed. Observe for at least 2 to 4 hours after adrenaline for rebound.
• Nebulised budesonide 2 mg is an alternative. Give humidified oxygen if oxygen saturation is under 92%.
• Admit for severe or recurrent stridor, poor response, young age, or unreliable home care. If intubation is needed, use a tube smaller than usual for age.

Prevention of recurrence.

• Treat the identified cause: airway surgery for stenosis or haemangioma (propranolol 1 mg/kg/day for infantile haemangioma, increased to 2 to 3 mg/kg/day in 2 to 3 divided doses under specialist direction), reflux therapy and allergy management.
• Review exposure to smoke, and avoid irritants.

Monitoring. Follow up after each episode and after endoscopy for growth and symptoms.

Referral and escalation. Refer to paediatric ENT or airway services after the second episode in a year, or after one severe episode in an infant.