Viral-Induced Wheeze

Viral induced wheeze is episodic wheeze in preschool children triggered by viral respiratory infections, with no symptoms between episodes.

• It affects up to a third of children by age 3 years, mostly aged 1 to 5 years.
• Triggers are rhinovirus, respiratory syncytial virus and other respiratory viruses.
• It is thought to reflect narrow airways in early childhood, and most children outgrow it by age 6 years.
• A minority develop asthma, especially with atopy, eczema, parental asthma, eosinophilia or wheeze between colds.

Wheeze accompanies the cold.

• Coryza, cough and fever, followed by wheeze and breathlessness on day 1 to 2 of a cold.
• Well between episodes with no night cough or exercise symptoms.
• Tachypnoea, subcostal recession, expiratory wheeze and hyperinflated chest.
• Severity ranges from mild to severe distress.
• Response to bronchodilator is often poor in infants.
• Differential diagnosis: asthma, bronchiolitis, foreign body, gastro-oesophageal reflux with aspiration, cystic fibrosis, tracheomalacia, vascular ring, heart disease and immunodeficiency.
• Complications: respiratory distress, hospital admission, hypoxia, and recurrence.

Diagnosis is clinical.

• History confirms symptoms only with colds and normal health between.
• Examination between episodes is normal; growth is normal.
• Chest X-ray not required unless atypical, focal signs or poor response.
• Consider atopy tests, sweat test or other investigations if wheeze is persistent, atypical or severe.
• Oxygen saturation in acute episodes.

Short-acting bronchodilator at onset of symptoms.

• Supportive: oxygen if saturation below 92 percent, fluids, parental education, avoid smoke exposure.
• Pharmacological: salbutamol 2 to 10 puffs (100 micrograms each) by spacer with mask, every 4 hours, increasing to every 20 minutes if needed in the first hour.
• Oral prednisolone 1 to 2 mg/kg once daily (maximum 20 mg in 2 to 5 years) for 3 days in moderate to severe attacks, especially in children with atopy or asthma risk. Ipratropium bromide 250 micrograms nebulised in severe episodes.
• Maintenance treatment is not routinely required. Montelukast 4 mg nightly (ages 2 to 5 years) for frequent attacks on a time-limited basis, or an inhaled corticosteroid for 4 to 8 weeks in recurrent or frequent episodes with atopy.
• Procedures: none routine. Hospital care with oxygen and respiratory support for severe attacks.
• Special groups: infants under 12 months need caution with bronchodilator effect.
• Red flags: severe breathlessness, cyanosis, poor feeding, exhaustion, and symptoms between viral illnesses.
• Follow-up: review in 1 to 2 weeks. If frequent or between-illness symptoms, reassess for asthma. Review again at 4 to 6 weeks if on time-limited treatment.