Clinical Notes : Respiratory

30. Acute Asthma in Adults


The diagnosis of asthma in adults (and children) 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

  • any triggers that make symptoms worse

  • 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.

  • Check for possible occupational asthma by asking employed people with suspected new-onset asthma, or established asthma that is poorly controlled:

    • Are symptoms better on days away from work?

    • Are symptoms better when on holiday?


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 -

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


Predicted Peak Flow calculator



  • Oxygen to all hypoxic patients (aim for SpO2 94-98%)

  • Nebulised high dose beta-agonists

    • preferably driven by oxygen

    • or high-dose beta 2 agonists by spacers

    • Increasing inhaler dosages within an exacerbation is not effective

  • Give steroids in adequate doses,

    • and continue for at least 5 days or until recovery

    • Overwhelming evidence for benefit in exacerbations but underused

    • Reduce admissions, relapse rates and symptom duration in asthma exacerbations


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



  • 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


Asthma : When to Refer

BMJ Best Practice.png

BTS/SIGN British guideline on the management of asthma

British Thoracic Society November 2016


Asthma: diagnosis, monitoring and chronic asthma management

NICE guideline [NG80] Published date: November 2017


British guideline on the management of asthma

SIGN Quick Reference Guide QRG 14. October 2014


Asthma in adults

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


White,J.,  Paton, J.Y., Niven, R. and and Pinnock, H. (2017)

Guidelines for the diagnosis and management of asthma: a look at the key differences between BTS/ SIGN and NICE

Thorax 2018;73:293–297


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