What is peak expiratory flow rate?

Peak expiratory flow rate (PEFR) or ‘peak flow’  is a simple bedside test of lung function, most commonly used in people with asthma or chronic obstructive airways disease (COAD).

How is a PEFR test performed?

A PEFR test is a quick and simple bedside measurement. A small tube with a slider device measures how fast air is driven through the tube by the subject exhaling rapidly.

The subject takes a deep breath in, then breathes out as hard and as fast as possible, with a good airtight seal of the lips around the tube.

This is best done standing up; the best of three attempts is usually taken, with a short rest between attempts.

When would you need a PEFR test?

A PEFR may be requested by your doctor for symptoms such as shortness of breath (dyspnoea), cough or wheezing.

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PEFR test results explained

The normal range for peak fow measurements depends on your gender, age, and height.

There is a reasonable ‘spread’ of normal values for any group of people with the same age, height and gender.

The individual’s “personal best” measurement is a more reliable guide to predicting an asthma attack or assessing the severity of illness.

Related specialists

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Also known as

  • Peak flow
  • PEFR



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This article is for informational purposes only and should not be taken as medical advice. If in doubt, HealthEngine recommends consulting with a registered health practitioner.