Author and Questions: Jo Anderson / Codes: ResC1, ResC11, ResP2, ResP4, SLO5 / Published: 21/01/2022

Wheeze and acute asthma in paediatrics

The child with respiratory distress can be difficult to assess, especially in the under 5’s. 

This is because intermittent wheezing attacks in young children are usually triggered by viral infections and their response to asthma medication may be inconsistent. 

The experts at BTS-SIGN have produced helpful guidance for managing asthmatic children over 1 year. However, use it with caution in 2-5 year olds who do not yet have a considered diagnosis of asthma and are presenting with a viral induced wheeze episode.

Children under 1 year are likely to have another cause for their wheeze. Consider bronchiolitis, tracheomalacia, complications of underlying conditions or congenital anomalies and don’t forget about first presentations of heart failure. 

Telling the difference between bronchiolitis and viral wheeze can be challenging (there is a whole blog about this that can help) – so if unsure, it is worth giving a trial of 5-10 puffs of salbutamol and having a second listen to their chest a few minutes after to see if there was any improvement. 

So do they have asthma?? 

Several factors are associated with increased probability that a child presenting with respiratory symptoms to PED will develop asthma or persisting wheeze throughout childhood. 

You don’t have to diagnose asthma in the PED but children with these factors may respond well to acute and preventative asthma treatments.

Prematurity and low birth weight 

  • Symptoms of wheeze, cough, breathlessness and chest tightness that vary over time
  • History of recurrent episodes (attacks) of symptoms
  • Previous recorded observation of wheeze heard by a healthcare professional (ED/GP attendances)
  • Personal/family history of other atopic conditions (atopic eczema/dermatitis, allergic rhinitis)
  • No symptoms/signs to suggest alternative diagnoses. 

Assessment of children with respiratory distress:

There are different scoring systems which can help you determine how severe their symptoms are. 

Ie  Moderate – Severe –Life threatening…… or   Table 17 in BTS guidelines – asthma severity scoring  

In your assessment look for:

  • Pulse rate
  • Respiratory rate and degree of breathlessness 
  • Use of accessory muscles of respiration 
  • Amount of wheezing 
  • Degree of agitation and conscious level

You can use these parameters to monitor improvement with treatment

What Tests: 

  • Pulse oximetry
  • PEF 
  • CXR is not routinely indicated
  • Blood gas measurements only if severe-life-threatening and not responding to treatment 

What about Peak flow? 

Peak expiratory flow (PEF) should be recorded as the best of three forced expiratory blows from total lung capacity with a maximum pause of two seconds before blowing. The patient can be standing or sitting. Children can normally manage this from age 4-5years. 

Mild-moderate = PEF ≥50% best or predicted

Acute – severe  = PEF 33–50% best or predicted

Life threatening = < 33% best or predicted

What if I’m not sure if it is asthma or viral induced wheeze?

The good news is that the acute treatment is the same! Start a trial of treatment salbutamol. If they have a good symptomatic and objective response, continue as required. 

Children with life-threatening asthma or SpO2 <92% should receive high-flow oxygen.

Plan A: Inhaled therapy

Inhaled β2 agonists is the first-line treatment for wheeze in children. 

For mild-moderate severity, give salbutamol via MDI and spacer. 

Check spacer technique! There are video aids available to help.

The dose is 5-10 puffs based on age and your local protocol. Inhalers should be actuated into the spacer in individual puffs and inhaled immediately by tidal breathing (for five breaths).

‘Burst’ salbutamol therapy can be used in moderate to severe cases in PED. This means giving 3 salbutamol doses 20 minutes apart before stretching doses out to 3-4hourly, at which point can safely go home.

Spacers or nebulisers??!!

A MDI + spacer is at least as good as a nebuliser at treating mild and moderate asthma attacks in children.

  • Less likely to have tachycardia and hypoxia than when the same drug is given via a nebuliser.   

If severe/life threatening, give salbutamol 2.5-5mg via a nebuliser in combination with nebulised ipratropium bromide.

What about steroids?

  • Oral steroids are not considered necessary for mild to moderate wheeze associated with viral infections. But in the acute situation, it is often difficult to determine whether a preschool child has asthma or episodic viral wheeze. 
  • For children with severe symptoms requiring hospital admission, even without an asthma diagnosis, it is still advisable to give oral steroids – but check your local protocol and consider the risk of frequent steroid use.
  • Oral and intravenous steroids are of similar efficacy – hold IV for those who cannot tolerate oral.  Some hospitals opt for oral dexamethose and others use prednisolone. 

# Do not give antibiotics routinely in the management of children with acute asthma.

Assessment of response should be based on accurately recorded clinical observations and repeat measurements of oxygenation. Do they need ward admission for oxygen or for slow stretching of salbutamol?

Plan B: Not responding to first line therapy?

IV magnesium sulphate given as a bolus has the lowest adverse side-effect profile and has been proven to work the fastest, but it doesn’t always work. Give it but get your next IV medication ready.  

IV salbutamol can be given as a bolus (15 micrograms/kg over 10 minutes) 

and/or is generally followed by a continuous infusion. Check your potassium and ECG before starting treatment and have the patient on an ECG monitor.

IV aminophylline is usually given as a loading dose (5 mg/kg over 20 minutes)

followed by a continuous infusion (omit the loading dose in those already on oral theophyllines) and have the child on an ECG monitor.

Consider complications –  ? pneumothorax, ?wrong diagnosis – ? anaphylaxis

#Transfer the patient to PHDU if on IV therapy or PICU 

What next?

Children can be discharged from the PED when stable with oxygen saturations normal sats +/- PEF >75%, on 3–4 hourly inhaled bronchodilators that can be continued at home.

-Check spacer technique
-Provide a wheeze /asthma action plan for subsequent attacks (including bronchodilator weaning advice). (Note this twitter thread too)
– Consider need for initiation or optimisation of asthma prevention treatment 
– Inform patient’s primary care practice within 24 hours of discharge 

Recurrent episodes of wheeze triggered by viruses does not always go on to develop atopic asthma but it is not a benign illness and these children benefit from good inhaler technique, education and access to salbutamol at home.


  1. BTS-SIGN Asthma guidelines July 2019
  2. RCH spacer technique