Croup

Croup is acute viral laryngotracheobronchitis causing barking cough, hoarseness, inspiratory stridor and respiratory distress from subglottic inflammation.

• It affects children aged 6 months to 6 years, peak at 1 to 2 years, with a seasonal pattern in autumn.
• Parainfluenza virus type 1 is the commonest cause. Other causes include influenza, respiratory syncytial virus, adenovirus and measles.
• Most cases are mild and last 3 to 5 days, with symptoms worse at night.
• About 1 to 5 percent of hospitalised children need intubation.
• Severity is classified by stridor at rest, retractions and general condition.

Illness starts with a coryzal prodrome.

• Upper respiratory symptoms and low-grade fever for 1 to 3 days.
• Barking (seal-like) cough, hoarse voice and inspiratory stridor.
• Mild: stridor only on crying or agitation, no resting stridor.
• Moderate: stridor at rest with mild to moderate chest retractions, but alert.
• Severe: marked stridor, severe retractions, cyanosis, agitation or lethargy, and tiring.
• Impending respiratory failure: drowsiness, pallor, reduced stridor from tiring (a bad sign).
• Differential diagnosis: epiglottitis, bacterial tracheitis, foreign body aspiration, retropharyngeal abscess, anaphylaxis, diphtheria (in unimmunised children), laryngomalacia, subglottic stenosis and angioedema.
• Complications: respiratory failure, hypoxia, pneumonia, bacterial tracheitis, pulmonary oedema and rare recurrence.

Diagnosis is clinical.

• Assess severity with oxygen saturation, respiratory rate and work of breathing. Avoid distressing the child (do not examine the throat with a spatula).
• Neck X-ray (steeple sign) is rarely necessary and only if the diagnosis is uncertain and the child is stable.
• Viral tests are rarely required.
• Consider foreign body, epiglottitis or tracheitis if the child is toxic, drooling, has a high fever, or fails to respond to treatment.

A single dose of corticosteroid is the mainstay.

• Supportive: keep the child calm and comfortable, in the parent's lap. Humidified air has no proven benefit. Encourage oral fluids. Give oxygen if saturation is below 92 percent.
• Pharmacological: dexamethasone 0.15 to 0.6 mg/kg once orally (maximum 10 mg) for all severities, or prednisolone 1 to 2 mg/kg once. Nebulised budesonide 2 mg is an alternative when oral therapy is not possible.
• Moderate to severe croup: nebulised adrenaline (epinephrine) 1:1000, 0.5 mL/kg up to 5 mL, observed for at least 2 to 4 hours after because of rebound. May repeat after 20 to 30 minutes.
• Antibiotics are not indicated unless bacterial tracheitis is suspected.
• Procedures: intubation with a tube smaller than expected for age, for impending respiratory failure, by an experienced operator.
• Special groups: children under 6 months, with underlying airway abnormality, Down syndrome, or no oral intake need closer observation. Unimmunised children with a grey membrane in the throat need throat swab testing for diphtheria.
• Red flags: stridor at rest, cyanosis, severe retraction, drooling, toxic appearance, lethargy, and not improving after steroids and adrenaline.
• Follow-up: home with safety-net advice if mild, or after observation. Return if stridor at rest, difficulty breathing or drinking. Recurrent croup needs airway assessment.