Wheezing in Children

Wheezing is a high pitched, whistling sound that occurs when smaller airways are narrowed by presence of any of the following:

• Bronchospasm
• Swelling of mucosal lining
• Excessive amounts of secretions
• Inhaled foreign body

• Common throughout childhood, except in immediate neonatal period when it relatively rare.
• 18.9% of 10 year old children shown to be wheezing on Isle of Wight with average age of onset of 3 years.¹

• Two main forms of presentation depending upon onset and age:
  • Acute onset of wheezing in an infant
  • Recurrent or persistent wheeze
• Wheezing starting perinatally suggests structural abnormalities.
• Clubbing occurs in chronic lung infection, congenital heart disease and rarely in uncomplicated asthma.
• Allergic rhinitis, urticaria and eczema suggest asthma (or an allergic reaction in a child with eczema).
• Nasal polyps are found in allergic conditions or cystic fibrosis.

Transient wheezing in infancy

• Transient early wheezing defines recurrent wheezing in non-atopic infants or toddlers and tends to disappear by the age of 3.²
• The most common cause for non-atopic wheezing is viral infection, especially by respiratory syncytial virus.²
• Short-term management with inhaled bronchodilators is sufficient if required.²
• Early sensitisation to indoor allergens, especially to pets, and atopic dermatitis predict subsequent development of asthma after wheezing in infancy.³
• If hospital admission for wheezing occurs in infancy, more than a third of children will suffer from asthma at early school age. The risk is significantly increased with recurrent wheezing in infancy and the development of allergic manifestations (e.g. blood eosinophilia, atopic dermatitis, elevated total serum IgE).

Bronchiolitis

• Bronchiolitis usually presents at age 1-9 months with 2-5 day history of cold symptoms with progressive tachypnoea (may occasionally reach above 100 breaths per minute), difficulty with feeding and gross hyperinflation. Fine crepitations, sometimes with rhonchi.
• Chest X-ray shows hyperinflation, occasionally with patchy areas of collapse/consolidation.⁴
• Nasopharyngeal secretions usually tested for respiratory syncytial virus, parainfluenzae, influenza A and B, adenovirus.
• Give oxygen to maintain transcutaneous O₂ saturation at above 92%.
• Monitor heart and respiratory rates. May require IV fluids or nasogastric tube feeding.
• Antibiotics used empirically for very ill child or evidence of pneumonia with secondary bacterial infection.
• Assisted ventilation via CPAP or endotracheal intubation is indicated if there is inadequate ventilation (i.e. rising CO₂ or falling oxygen saturations), severe respiratory distress, falling level of consciousness, exhaustion, cyanosis or respiratory failure.
• Infants usually recover within 10-14 days but may have recurrent bouts of coughing and wheezing for several years.⁵

Recurrent or persistent wheeze

• Caused by obstruction anywhere from intrathoracic trachea to large bronchioles.
• Wheezing persisting for or recurring for more than 4 weeks is most commonly caused by reactive airways disease (asthma).
• This diagnosis is also suggested by recurring cough and response to bronchodilator therapy.

Other causes

• Cigarette smoke or other forms of pollution
• Infection-associated airways reactivity
• Asthmatic bronchitis
• Other hypersensitivity reactions
• Aspiration of foreign body: often sudden onset of severe wheezing in previously healthy child (look for tracheal deviation)
• Cystic fibrosis
• Gastro-oesophageal reflux

Rarer causes

• Aspiration of food, saliva or gastric contents (laryngotracheo-oesophageal cleft; tracheo-oesophageal fistula; pharyngeal incoordination or neuromuscular weakness)
• Primary ciliary dyskinesia
• Heart failure
• Bronchiectasis
• Bronchiolitis obliterans
• Extrinsic compression of airways (tumours, vascular rings, etc.)
• Tracheobronchomalacia
• Endobronchial masses
• Pulmonary haemosiderosis
• Sequelae of bronchopulmonary dysplasia
• 'Hysterical' glottic closure

• Chest X-ray: can demonstrate presence of foreign body, structural anomalies, enlarged heart, masses, pulmonary infiltrates
• Sweat chloride test for cystic fibrosis
• Allergy testing
• Barium swallow for tracheo-oesophageal fistula and other anomalies⁶
• Spirometry in children aged over 6 years

May need further investigations for rarer causes, e.g. echocardiogram, MRI/CT scan of chest.