Introduction

• Affects children under the age of 5 years old
• There tends to be two patterns of recurrent wheezing in this age group:
  • Episodic and viral induced wheezing which occurs as discrete episodes of wheeze secondary to viral infections and the child is well in between these episodes with no signs of respiratory distress
  • Multi-Trigger wheeze which presents as wheezing with upper respiratory tract infections but also with allergic triggers and airway irritants, e.g. pollution, smoke, house dust mite, pets
• Episodic viral induced wheezing has a different underlying pathophysiology to atopic asthma and children with viral induced wheeze do not all go on to develop asthma, hence why not all children who wheeze are diagnosed as asthmatic.
• Viruses trigger wheeze through infection of respiratory epithelial cells which leads to the release of inflammatory cytokines, promoting cellular infiltration by T cells, eosinophils and basophils. These go on to release inflammatory mediators and lead to airway inflammation and hyperresponsive bronchioles, causing airway obstruction. (Gern JE, 2002)
• There is a link between bronchiolitis and subsequent episodes of viral induced wheeze. Studies have shown around 40-50% of infants with RSV bronchiolitis go on to have recurrent wheezy episodes (Bacharier LB, 2012)

History

• How long have they been unwell for?
• Has there been a preceding cold like illness or is anyone else at home unwell with a cold?
• Have they been managed for wheeze before? If so, did they need any IV medication or to go to HDU / PICU? (This predicts increased severity of disease. If you see a child with wheeze who has previously had a HDU or PICU admission for wheeze you should have a very low threshold to admit)
• If they have been managed for wheeze before do they have a salbutamol inhaler? This is a good point in the history to check inhaler technique and ensure they are using a spacer
• Are they prescribed preventers? Such as a clenil inhaler or montelukast
• Are they feeding well?
• Are they growing and developing well?
• Is there a personal or family history of atopy?
• Is there a history of interval symptoms? (nocturnal cough, cough/ shortness of breath/ audible wheeze on exertion, cough/ shortness of breath/ audible wheeze in response to allergens such as pet hair)
• Are there any smokers at home? – This is important as second hand smoke inhalation can trigger wheeze and this is an opportunity for you to give smoking cessation advice to the parents
• Are there pets at home?

Examination

• Signs of increased work of breathing (subcostal, intercostal recession, tachypnoea, tracheal tug, abdominal breathing, sternal recession, nasal flaring, head bobbing, grunting)
• Check oxygen saturations, do they look cyanosed?
• On auscultation there will be widespread expiratory wheeze, there may be a prolonged expiratory phase
• If the chest is particularly tight you may not hear much as there will be reduced air entry. In cases like this where you are unsure if you can hear wheeze you can give a one off salbutamol neb and re-auscultate and you may start to hear wheeze as they open up.
• Are they able to talk in full sentences?
• Whilst examining make sure to look for other signs of viral URTI such as coryza, cough, low grade fever.
• Also look out for signs of atopy, e.g. eczema, allergic rhinitis
• If you feel there is an underlying chronic lung condition look for signs such as clubbing, faltering growth, Harrisons sulcus (this is a horizontal groove seen along the chest wall which occurs secondary to chronic excessive diaphragmatic usage with persistent respiratory distress)
• An ENT examination is always useful to looks for signs of a viral URTI such as red inflamed tonsils and cervical lymphadenopathy. However, if the child is very short of breath this can wait until they are more stable

Differentials

• Inhaled foreign body– In the case of an inhaled FB there will usually be a history of very sudden onset of coughing / choking with increased work of breathing, Wheeze will also often be focal rather than widespread and there may be a stridor
•  Anaphylaxis – Anaphylaxis can present with severe wheeze but there will also be other signs of allergic reaction such as angioedema, urticarial rash and history of allergen exposure
• Mediastinal mass- This tends to present as severe refractory wheeze in older age groups but it is important to keep in the back of your mind with a child with wheeze who is not responding well to bronchodilators
• Bronchiolitis – Between the ages of 1-2 years it can be difficult to distinguish between bronchiolitis and viral induced wheeze. In bronchiolitis there are often widespread crackles audible with wheeze and they won’t respond well to bronchodilators
• Underlying lung disease such as PCD / bronchiectasis / CF – these will often come with other signs and symptoms such as failure to thrive, recurrent lower respiratory tract infections, persistent wet cough

Investigations

• Viral NPA to identify if there is an underlying viral cause for the wheeze
• If moderate – severe increased work of breathing consider a capillary blood gas
• Bloods and CXR are rarely warranted in these situations. Neither are likely to influence your management plans / decision making. However, the exception to this would be if the wheeze is severe and you’re considering magnesium sulphate or escalation to highflow. This is to make sure you’re not missing a large pneumonia / effusion / collapse / mediastinal mass / foreign body

Management

Dependant on severity which can be graded similar to an exacerbation of asthma

*Back to back combi nebs means 3 combi nebs given one after the other or every 20 minutes. At the time of deciding to start back to back nebs, it is a good idea to also put emla/ametop cream on the child (a local anaesthetic used for cannulation) in case you need to escalate your management to IV treatment

Antibiotics are rarely useful in the management of wheeze but if a child is febrile and very unwell or if there are signs of a focal lower respiratory tract infection it would be reasonable to cover with antibiotics, either amoxicillin or a macrolide such as azithromycin.

NICE guidance advises prescribing a short course of oral prednisolone (3 days) if there is a diagnosis of asthma or a significant personal or family history of atopy.

The BTS (British Thoracic Society) recommends a 3 day course of pred for preschool children with moderate or severe wheeze.

Reasons for Admission

• Oxygen requirement
• Requiring salbutamol more frequently than 4 hourly to control symptoms
• If the child has previously been admitted to HDU / PICU for wheeze but looks relatively well this time it would still be reasonable to refer for a paediatric opinion
• Refer to paediatrics if the child has any features of a chronic underlying condition which has been undiagnosed, such as a wet cough, failure to thrive, clubbing etc.

Safety Net Advice for Discharge

• Give the parents a reasonable stretching plan for salbutamol. Most trusts have leaflets on the intranet with wheeze step down plans but there are also generic plans on asthma charity websites
• There is no fixed way to stretch out inhalers but generally we discharge once the child is on 6 puffs 4 hourly, then tell the parents to stretch every 24 hours, first to 4 puffs 4 hourly, then 2-4 puffs every 4-6 hours, then 2-4 puffs as and when needed. Advise the parents if they are worried about the childs respiratory effort or if they start to sound very wheezy again, to give 10 puffs of salbutamol and bring to ED. Also advise them to bring back to ED if they are needing to give salbutamol more often than 4 hourly
• If the child has had frequent admissions with wheeze it would be reasonable to discharge them on a preventer medicine (either a beclametasone inhaler or montelukast) but this would be a consultant decision and they would need follow up.
• NICE guidance states that all children with wheeze who are not admitted to hospital need follow up within 2 working days. This is usually best done by community nurses but you can also ask the GP to follow up.

Evidence Base

• A 2013 Cochrane review showed that beta-agonists given via a spacer are as effective as nebulised treatment in managing moderate – severe asthma when there is no oxygen requirement. Furthermore, children who received beta-agonists via a spacer have a reduced length of stay in ED compared to those who received nebulised beta-agonists. (Cates CJ, 2013)
• There have been many studies looking at the efficacy of steroids in reducing length of hospital stay and the majority conclude that steroids are not particularly useful in pre-school wheeze.
  • An RCT in 2009 compared a 5 day course of oral pred in children aged 10 months to 6 years presenting to hospital with wheeze, to placebo. This found no significant difference in duration of hospitalisation between the two groups. Oral pred was found to not be superior to placebo in this study. (Panickar J, 2009)
  • A systematic review and meta-analysis undertaken in 2019 looked at the evidence for oral steroids in pre-school wheeze and found good evidence that oral steroids should not be used routinely in the management of pre-school wheeze in the ED. There was uncertain evidence regarding the efficacy of steroids in children with severe wheeze who are hospitalised. (Murphy J, 2019)
  • A 2021 RCT in Auckland compared 2mg/kg prednisolone to placebo in children presenting with acute wheeze aged 24-59 months and found no difference in outcomes at 24 hours or beyond between the two groups. (Wallace A, 2021)

Bibliography

Bacharier LB, C. R. (2012). Determinants of Asthma After Severe Respiratory Syncytial Virus Bronchiolitis. The Journal of Allergy and Clinical Immunology, 91-100.

Cates CJ, W. E. (2013). Cochrane Review: Holding Chambers (Spacers) Versus Nebulisers for Delivery of Beta-Agonist Relievers in the Treatment of an Asthma Attack. Cochrane Library.

Gern JE, B. W. (2002). Relationship of Viral Infections to Wheezing Illnesses and Asthma. Nature Reviews Immunology, 132-138.

Murphy J, K. ,. (2019). Oral Steroids For Preschool Children With Acute Wheeze: A Systematic Review and Meta-Analysis. European Respiratory Journal.

Panickar J, L. M. (2009). Oral Prednisolone for Preschool Children with Acute Virus-Induced Wheezing. The New England Journal of Medicine, 329-338.

Wallace A, S. O. (2021). Impact of Oral Corticosteroids on Respiratory Outcomes in Acute Preschool Wheeze: A Randomised Clinical Trial. BMJ: Archives of Disease in Childhood.

Written by Dr Rebecca Evans Paediatrics ST3