History and exam

Key diagnostic factors

common

shortness of breath

An increase in shortness of breath (including too breathless to complete sentences in one breath).

One of the symptoms of the ‘classic triad’ of asthma exacerbation symptoms.

Look for progressive worsening.[1] The degree of breathlessness is an aid in determining the severity of the exacerbation. Inability to complete sentences in one breath is a marker of acute severe asthma.[13]

cough

One of the symptoms of the ‘classic triad’ of asthma exacerbation symptoms.

Atypical presentation with predominant cough should raise the possibility of pertussis infection, which can be a mimic or trigger of an asthma exacerbation.[1]

wheeze

One of the symptoms of the ‘classic triad’ of asthma exacerbation symptoms. Look for progressive worsening.[1]

A patient with asthma in extremis without wheezing (so-called ‘silent chest’; due to severely decreased airflow) may be an indication of impending respiratory failure; however, other signs of respiratory failure are likely to be present too.[1]

risk factors

Ask about risk factors, such as:[1][13]

  • History of previous asthma attacks

    • In particular, near-fatal asthma requiring intubation or mechanical ventilation, or hospitalisation or emergency care for asthma in the last year.

  • Poor control

  • Inappropriate or excessive short-acting beta-2 agonist use

  • Age[13]

    • Elderly patients may be more at risk and require specialist care.

    • Reports indicate that people aged 18-29 have a high prevalence of poorly controlled asthma and an increased likelihood of an exacerbation.[48]

  • Female sex[13]

  • Reduced lung function

    • A decrease in home peak expiratory flow (PEF) measurements.

    • The Global Initiative for Asthma (GINA) advises that a low FEV₁, especially <60% predicted, is an important risk factor for exacerbations, even if the patient has few asthma symptoms.[1]

  • Obesity

  • Smoking (including e-cigarettes/vapes)

  • Depression, other psychological disease, or major psychosocial or socioeconomic problems

  • A history of anaphylaxis[13]

  • Food allergy

  • Comorbid gastro-oesophageal reflux disease

  • COPD[13]

  • Raised FeNO at routine reviews

    • GINA advises that elevated FeNO in adults with allergic asthma who are taking inhaled corticosteroids is associated with increased risk of exacerbations even in patients with few asthma symptoms.[1]​ Regular FeNO testing may lead to a reduction in exacerbations.[34]​

  • Blood eosinophilia

    • High blood eosinophil count, reflecting type 2 inflammation, is a risk factor for asthma exacerbations.[51]

  • Poor adherence with prescribed preventer (controller) medication, or poor engagement with routine asthma review or follow-up.

  • High bronchodilator reversibility[1]

  • Chronic rhinosinusitis[1]

  • Pregnancy[1]

progressive chest tightness

A symptom of impaired airflow.

progressive decrease in lung function

Measure PEF (before initiating treatment, if possible to do this without inappropriately delaying management) to help assess severity and direct decisions about management.[1][13]​ In acute settings, PEF may be more reliable than symptoms for determining exacerbation severity.[1]​ Consider the following peak flow criteria:[13]

  • Life-threatening asthma: PEF <33% of best or predicted

  • Acute severe asthma: PEF 33% to 50% of best or predicted

  • Moderate asthma: PEF >50% to 75% of best or predicted

Consider PEF in the context of other markers of severity. PEF alone does not determine the severity of an exacerbation. See  Diagnosis recommendations.

Enquire about a decrease in home PEF measurements.

tachypnoea

A sign of dyspnoea and airflow obstruction.

Measure respiratory rate.[1][13]

  • Respiration ≥25 breaths/minute indicates acute severe asthma.[13]

tachycardia

Measure pulse rate.[1][13]

  • Pulse ≥110 beats per minute indicates acute severe asthma.[13]

silent chest

Due to severely decreased airflow.[1]​ May be an indication of impending respiratory failure; however, other signs of respiratory failure are likely to be present too.[1]

An indication of a life-threatening exacerbation.[1][13]

accessory muscle use

Look for accessory muscle use as this is a sign of respiratory distress.

sleep disturbance

Nocturnal awakenings due to uncontrolled asthma or asthma-induced cough are common and are one of the criteria commonly used to stratify recent asthma control.[1]

Other diagnostic factors

common

exercise limitation

Exercise may be a trigger of asthma symptoms and its limitation may indicate an acute worsening of asthma.[1]

collapse

May be present together with other clinical features. May indicate a patient with severe asthma.[13]

altered consciousness

An indication of a life-threatening exacerbation.[13]​ Confusion and drowsiness may be caused by hypoxia and/or hypercapnia.[1]

skin symptoms

Enquire about and look for any associated skin symptoms, such as eczema. This indicates a history of other atopic disorders.[13]

uncommon

cyanosis

Indicates severe hypoxaemia.

An indication of a life-threatening exacerbation.[13]

arrhythmia

An indication of a life-threatening exacerbation.[13]

hypotension

An indication of a life-threatening exacerbation.[13]

exhaustion

An indication of a life-threatening exacerbation.[13]

stridor

May also indicate an alternative aetiology of the clinical presentation, such as vocal cord dysfunction.

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