Key learning points
- Preschool wheeze is associated with significant morbidity
- A thorough history is key to diagnosis
- Educating parents about inhaler technique, concordance with medication and the need to use preventer and reliever medications is important in symptom management
- Many children with preschool wheeze can be managed with watchful waiting and as-needed symptom relief
Wheeze has been defined as ‘a continuous high-pitched sound with musical quality emitting from the chest during expiration’.1,2 It should not be considered as a standalone disorder but rather a clinical finding that suggests narrowing or obstruction in some part of the respiratory airways. Airway narrowing by secretions, airway wall oedema, will produce a wheeze that does not respond to bronchodilators. Airway malacia, fixed intrinsic or extrinsic narrowing, also leads to bronchodilator unresponsive wheeze.
Preschool wheeze is increasingly common,3 and has a major impact on children and their families because of the significant morbidity associated with acute episodes. It has been classified into transient, persistent and late-onset wheeze or other latent classes.4–6 While such classifications may help us understand the mechanisms and natural history of preschool wheeze, they are not much use to clinicians in diagnosis.
For a more useful classification that can help to guide management, a European Task Force proposed dividing preschool wheeze into two groups according to symptoms: episodic viral wheeze (EVW) and multiple-trigger wheeze (MTW), which resembles classical asthma.1,7 However, intra-patient variation and overlap in phenotype over time, as well as within-patient phenotype switching,8,9 means a reliable distinction between EVW and MTW, deduced from the clinical history, may not be always possible.
Multiple and complex factors interact in the development, persistence and phenotypes of preschool wheeze and it can be challenging to diagnose and treat. It is associated with many diseases so management is easiest when the underlying disorder is accurately identified. Otherwise managing wheeze is akin to managing abdominal pain or fatigue when the underlying cause is not known.11
A focused history is the key to diagnosing preschool wheeze. It should be remembered that some conditions give rise to noisy breathing and could be misinterpreted as wheeze. It can be difficult to distinguish EVW from acute bronchiolitis in young infants. The healthcare professional needs to confirm wheeze reported by parents.10,12
The history should assess the frequency, persistence and severity of episodes; and whether they required hospital, paediatric intensive care or high dependency unit admissions.10
How the child responded to previous treatments and any unusual or atypical features that would suggest another underlying condition should be ascertained. Investigations are not usually needed unless wheezing episodes are very frequent and/or unusually severe, if they are resistant to treatment, are accompanied by unusual features or when the diagnosis is unclear.10
Non-pharmacologic management measures including any avoidance of secondhand smoking or vaping should be emphasised. Although avoiding inhaled allergens may be desirable in MTW, the measures needed as well as the costs may be prohibitive.10
As well as teaching good inhaler technique, parents need education to understand how treatment can reduce the severity of wheezing episodes, so a discussion about why their child needs to continue treatment when they appear well is important, as well as the reason for using both reliever and preventer medications. A written personalised acute management plan should be discussed and provided.10
A course of daily inhaled corticosteroids should be initiated for any child with very frequent and/or severe symptoms, while intermittent high-dose inhaled corticosteroids may be better for those with moderate-to-severe EVW. There is no guidance about the exact frequency and severity of wheezing episodes that would warrant initiation of daily therapy or the optimum duration of therapy. Therefore an 8-week trial of low-dose maintenance inhaled corticosteroids would appear sensible. The results of any treatment regimen should be reviewed regularly.10,11
However, using corticosteroids long-term does not appear to change the course of the disease later in life. There is no evidence to support the use of montelukast as intermittent or maintenance treatment, although a small subgroup of children with a 5/5 ALOX5 promoter genotype may derive benefit.10,13–17
Azithromycin has had mixed results in treating preschool wheeze. A randomised controlled trial of azithromycin in children with recurrent asthma-like symptoms showed that it was associated with a significant reduction in the duration of symptoms, particularly when initiated early in the episode.18 Another study found a reduced likelihood of severe lower respiratory tract illness developing in children with recurrent severe wheezing when it was used early in the illness.19 However, a study in which azithromycin was given to preschool children presenting to an emergency department found that it did not reduce the duration of respiratory symptoms or the time to respiratory exacerbation in the six months after treatment.20
Watchful waiting, along with as-needed symptom management, may be a safe approach for many children with preschool wheeze.21
Dr Jayesh Mahendra Bhatt is a consultant respiratory paediatrician at Nottingham Children’s Hospital
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