Case Study : Respiratory

164. Acute asthma

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Breathlessness of sudden onset

Presentation : A 28-year-old man attends a same-day appointment reporting sudden-onset breathlessness the previous night.

During the consultation, his breathing rate is normal and chest auscultation reveals mild expiratory wheeze.

Peak expiratory flow rate (PEFR) is 510 l/min and he says he only attended because his partner told him to.

His records show that he has a repeat prescription for salbutamol


The IMPRESS algorithm is designed to assist clinicians during the initial assessment of a patient presenting with acute or chronic breathlessness and is intentionally broad-based because of the large number of possible diagnoses.(1) 

These algorithms reflect that a patient may well have more than one condition contributing to the symptom of breathlessness and the existence of terms such as ‘cardiac asthma’ demonstrates that it is very easy to be led astray by symptoms more typical of other causes.

Important aspects of a clinical assessment of breathlessness

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Despite improvement of the patient’s symptoms by the time of presentation, it is likely that he experienced an episode of asthma of unknown severity the previous night.


Further questioning, including discussion of a past episode, suggests that this patient’s trigger is exposure to cat hair.

It is an important part of asthma care planning for patients to be aware of their individual triggers.(2) (3)

Be aware that the normal ranges for peak flow measurement in younger adults are quite high (depending on age, gender, and height) so it is sensible to calculate PEFR as a percentage of the predicted (or best-ever) reading.

For this patient, the reading was somewhat below the expected figure, but the history suggests that the overnight episode may well have met the criteria for a severe exacerbation of acute asthma.

Night-time waking or significant diurnal or day-to-day variability of symptoms should alert the clinician to the possibility of asthma. (2)


Clinical features differentiating COPD and asthma4

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For this patient, whose symptoms have improved spontaneously, re-prescribing past reliever medication (salbutamol inhaler) alongside an assessment of inhaler technique is likely to cover the immediate episode, provided that no further exposure to the patient’s trigger occurs.


However, because of the uncertainty of the severity of the episode overnight, a short course of oral corticosteroid (prednisolone 40–50 mg daily) may also be considered (steroid tablets are as effective as injected steroids, provided they can be swallowed and retained). (2)


Safety-netting advice should be given in case of recurrence and a plan made for future asthma review in case this episode heralds a change in previously intermittent asthma.

Clinical outcome

This patient responded well to beta2-agonist treatment alone and his symptoms cleared fully within 2 days.


Going forward, he made arrangements to avoid contact with his friend’s cat and his medical notes were updated to accurately reflect his condition of allergic asthma.


1. Acute breathlessness assessment

Improving and Integrating Respiratory Services in the NHS (IMPRESS).

The Health Foundation,




2. British guideline on the management of asthma.

British Thoracic Society (BTS) and the Scottish Intercollegiate Guidelines Network (SIGN).

SIGN Guideline 153.



3. Your asthma action plan.

Asthma UK 

Last updated September 2018


4. Chronic obstructive pulmonary disease in over 16s: diagnosis and management.

NICE Clinical Guideline CG101.

June 2010.


Breathlessness: what's the diagnosis?

Dr Chris Cooper

Guidelines in practice

October 2017


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