Asthma and Airway Centre

Managing Asthma

Peak Flow Monitoring

A peak flow metre is used to assess lung function by measuring the fastest flow of expired air. Peak flow metres are available in different colors, shapes and sizes, but the technique is basically the same.

Your peak expiratory flow rate (PEFR) is helpful in assessing how open or narrow your airways are. It can be measured at home whenever you have concerns about your asthma control.

Your doctor will calculate what your predicted peak flow rate should be (according to your height, age and sex) and will give you an action plan based on your best values.

It requires your best effort when using the peak flow metre, otherwise you will get misleading results.

Peak flow monitoring should be done early in the morning and in the evening or when you are not feeling well. It is helpful in diagnosing exercise induced asthma and occupational (job-related) asthma. If occupational asthma is suspected your doctor may recommend that you do your peak flows at home and work.

You may be asked to record your peak flow rate before and 15 minutes after a bronchodilator (relief inhaler) to assess its effect. Your nurse or doctor will show you how to record your peak flow rates.

Learn how to create a Peak Flow Action Plan and How to Use Your Peak Flow Metre.