Clinical Notes : Paediatrics

29. Acute asthma in children

Clinical history


The diagnosis of asthma in children (and adults) is based on the recognition of a characteristic pattern of

respiratory symptoms, signs and test results and the absence of any alternative explanation for these.

  • Take a structured clinical history in people with suspected asthma.

  • Specifically, check for:

    • wheeze, cough or breathlessness, and any daily or seasonal variation in these symptoms

    • More than one of the symptoms of wheeze, breathlessness, chest tightness and cough occurring in

    • episodes with periods of no (or minimal) symptoms between episodes. Note that this excludes cough as

    • an isolated symptom in children. For example:

      • a documented history of acute attacks of wheeze, triggered by viral infection or allergen exposure with symptomatic and objective improvement with treatment

      • recurrent intermittent episodes of symptoms triggered by allergen exposure as well as viral infections

      • and exacerbated by exercise and cold air, and emotion or laughter in children

      • any triggers that make symptoms worse

        • symptoms triggered by taking non-steroidal anti-inflammatory medication (e.g. ibuprofen)

    • a personal or family history of atopic disorders.

  • Do not use symptoms alone without an objective test to diagnose asthma.

  • Do not use a history of atopic disorders alone to diagnose asthma.


Expiratory wheeze

Wheezes are adventitious lung sounds that are continuous with a musical quality.

Wheezes can be high or low pitched. High pitched wheezes may have an auscultation sound similar to squeaking.

Lower pitched wheezes have a snoring or moaning quality.

The proportion of the respiratory cycle occupied by the wheeze roughly corresponds to the degree of airway obstruction.

Wheezes are caused by narrowing of the airways.

Expiratory wheeze -

Monophonic wheeze

Monophonic wheezes are loud, continuous sounds occurring in inspiration, expiration or throughout the respiratory cycle.

The constant pitch of these sounds creates a musical tone.

The tone is lower in pitch compared to other adventitious breath sounds. The single tone suggests the narrowing of a larger airway.

These lung sounds are heard over anterior, posterior and lateral chest walls.

These sounds can be more intense over lung areas affected by partial obstructions.

Monophonic wheeze -

Polyphonic wheeze

Polyphonic wheezes are loud, musical and continuous. These breath sounds occur in expiration and inspiration and are heard over anterior, posterior and lateral chest walls.

These sounds are associated with COPD and more severe asthma.

Polyphonic wheeze -

Determine probability of asthma

  • Low probability

    • If there is a low probability of asthma and/or an alternative diagnosis is more likely, investigate for the alternative diagnosis and/or undertake or refer for further tests of asthma.

    • Asthma diagnosis is now generally reserved for children over the age of 5. Before this, consider “preschool wheeze”.

  • Intermediate probability

    • Children who have some, but not all, of the typical features of asthma on an initial structured clinical assessment or who do not respond well to a monitored initiation of treatment have an intermediate probability of asthma.

  • High probability

    • The structured clinical history will single out those children with a high probability of asthma

Assess severity

  • Moderate exacerbation

    • PEF>50-75% best or predicted

    • increasing symptoms

  • Acute severe (admit if failing to respond to treatment)

    • PEF 33-50% best or predicted

    • inability to complete sentences

    • polyphonic wheeze

    • RR>25

  • Life threatening (emergency admission)

    • PEFR<33% best or predicted

    • Spo2 <92%

    • silent chest

    • poor respiratory effort

    • arrhythmia

    • exhaustion or altered conscious level


Record  clinical signs

  • Clinical signs correlate poorly with the severity of airways obstruction.

    • Some children with acute severe asthma do not appear distressed

  • Pulse rate

    • Increasing tachycardia generally denotes worsening asthma

    • A fall in heart rate in life-threatening asthma is a pre-terminal event

  • Respiratory rate and degree of breathlessness

    • Too breathless to complete sentences in one breath or to feed

  • Use of accessory muscles of respiration

    • Best noted by palpation of neck muscles

  • Amount of wheezing

    • Might become biphasic or less apparent with increasing airways obstruction

  • Degree of agitation and conscious level

    • Always give calm reassurance


In children under 2 with acute wheezing

  • Intermittent wheezing attacks are usually due to viral infection and the response to asthma medication is inconsistent

  • Prematurity and low birth weight are risk factors for recurrent wheezing

  • The differential diagnosis of symptoms includes

    • Aspiration pneumonitis

    • Pneumonia

    • Bronchiolitis

    • Tracheomalacia

    • Complications of underlying conditions such as congenital anomalies and cystic fibrosis

  • Refer all children <2


  • In children 5-12 the Metered Dose Inhaler (MDI) through a spacer is as effective as nebulisation

    • take 5 breaths through MDI per dose

  • Mild-moderate asthma attacks should be treated with MDI and spacer reserving nebulized medication for severe attacks

  • Prednisolone should be administered early and in high doses


Moderate asthma :

Salbutamol via pMDI (spacer) 1 puff every minute up to 10 puffs is as effective as nebulised salbutamol

Severe asthma :

only one attempt at nebulisation

then refer if not resolved 


If poorly responsive to Salbutamol, then switch to Ipatropium

0,25 mg via O2 driven nebuliser in child <2

0,5 mg via O2 driven nebuliser in adult


Moderate asthma : repeat every 30 minutes for 2 hrs

Severe asthma : refer after first failed attempt

Predicted Peak Flow calculator



  • Admit any patient with an acute severe attack failing to responds to treatment as evidenced by

    • Worsening PEFR

    • Worsening or persisting hypoxia

    • Exhaustion

    • Confusion, drowsy, altered metal state

    • Respiratory arrest 

  • Admit any patient with a life threatening attack

Second line medication in A+E includes

  • intravenous salbutamol (15 micrograms/kg over 10 minutes)

  • aminophylline

  • intravenous magnesium sulphate (40 mg/kg/day)


Asthma : When to Refer

BMJ Best Practice.png

Diagnosis and management of asthma in children

Andrew Bush, Louise Fleming.

BMJ 2015;350:h996. March 2015.


British guideline on the management of asthma

SIGN Quick Reference Guide QRG 14.

October 2014


Asthma in children

BMJ Best Practice

January 2019



2018 GINA Report, Global Strategy for Asthma Management and Prevention

The Global Initiative for Asthma


Australia's National Guidelines for Asthma Management

The Australian Asthma Handbook v1.3

December 2017


Australian Asrhma Handbook.png
Ireland notes.png

CPD Quiz and Certificate

This activity attracts 1,0 CPD point

29. Asthma child.jpg

Scroll down the box above to view its entire content

All users who successfully complete the quiz are e-mailed a copy of their personalised CPD certificate.