Wheezing in Infants and Preschool Children
On this page
Direct answer
Wheezing in infants and preschool children reflects airway narrowing, and most early episodes are triggered by viral infection rather than asthma. The asthma predictive index identifies children who are likely to have asthma at school age, separating persistent wheezers from transient early wheezers. Before accepting a diagnosis of asthma in this age group, bronchiolitis, foreign body aspiration and structural or congenital airway causes must be excluded.
What you must remember
- Transient early wheezers: children who wheeze in the first three years and settle by about six years, often linked to small airways, prematurity or smoke exposure.
- Persistent wheezers: children whose asthma-like features continue into school age, often with atopy in the child or family.
- Asthma predictive index: major criteria are parental asthma, physician-diagnosed atopic dermatitis and sensitisation to inhalant allergens; minor criteria are wheeze apart from colds, sensitisation to milk, egg or peanut, and eosinophilia of at least four per cent.
- Positive index: requires at least four wheezing episodes in the past year (at least one physician-diagnosed) plus one major or two minor criteria.
- Bronchiolitis: usually the first episode in a child under two, often caused by RSV, with coryza and fine crackles.
- Foreign body: sudden onset with focal wheeze or reduced breath sounds on one side points to aspiration.
- Other causes: vascular ring, tracheomalacia, gastro-oesophageal reflux, cystic fibrosis and immunodeficiency must be considered in atypical cases.
Transient or persistent: a practical comparison
A 2-year-old has had several wheezing episodes since birth, each with a cold, and his father has asthma. The question is whether he is a transient or a persistent wheezer, and the comparison below separates the two groups.
| Feature | Transient early wheezer | Persistent wheezer |
|---|---|---|
| Pattern | Wheeze in the first three years, usually with colds | Wheeze continuing into school age |
| Lung function | Reduced at birth, linked to small airways | Asthma-like airway inflammation |
| Typical triggers | Viral infection, smoke exposure, prematurity | Allergens and viral triggers |
| Atopy | Usually absent | Often present, including eczema or sensitisation |
| Asthma predictive index | Usually negative | Often positive |
| Follow-up | Review at school age | Review regularly and consider controller therapy |
The index is used to decide on preventive treatment and follow-up, not to diagnose asthma in a child who is wheezing today. A transient wheezer usually needs only short-acting treatment during episodes, and parents are counselled that most early wheezers outgrow their symptoms and that avoiding smoke exposure helps.
Where the exam tries to catch you
Students lose marks by treating the index as a diagnostic test or by starting daily steroids too early.
- Trap: treating the asthma predictive index as a diagnostic test Correct: the index predicts asthma later in childhood, and it does not confirm asthma in a child who is wheezing today.
- Trap: starting daily inhaled corticosteroids for every wheezing toddler Correct: transient early wheezers respond to short-acting bronchodilators during episodes, and daily controllers are reserved for persistent disease.
- Trap: calling a first wheezing episode in a 9-month-old asthma Correct: bronchiolitis, often from RSV, is the usual first episode, and asthma in this age group is a clinical diagnosis made after recurrence.
Frequently asked questions
What is the asthma predictive index?
The asthma predictive index is a tool that predicts which preschool children with recurrent wheeze are likely to have asthma at school age. A positive index requires at least four wheezing episodes in the past year, one of them physician-diagnosed, plus one major or two minor criteria, and it guides follow-up and preventive treatment.
Which features distinguish bronchiolitis from asthma in a toddler?
Bronchiolitis is usually a first episode in a child under two years, often caused by RSV, with coryza, fine crackles and a viral prodrome. Recurrent episodes, a family history of atopy and a response to bronchodilators favour asthma, but in a toddler the diagnosis remains clinical.
What is the first-line treatment for an acute wheezing episode in a preschool child?
A short-acting beta-2 agonist given through a spacer with a mask is the first-line treatment for an acute wheezing episode in a preschool child. Oral corticosteroids are added for severe or prolonged episodes, and daily controllers are reserved for persistent wheezers.
Why must foreign body aspiration be excluded in a child with wheeze?
Foreign body aspiration must be excluded because it causes sudden, focal wheeze that can mimic asthma and may need bronchoscopy. Reduced breath sounds on one side and a history of choking are the key clues, and a normal chest X-ray does not exclude it.