Peak flow spirometer: what to know

A peak flow result is most useful when compared with your own usual readings and symptoms. Spirometry may show how much air you exhale and how quickly, including whether airflow changes after a bronchodilator. Results depend on effort, technique, age, height, and health. A number on its own cannot explain every cause of cough or breathlessness, so interpretation belongs with the clinical history.

Use the device exactly as demonstrated and keep your body position consistent for home monitoring. For a clinic test, wear comfortable clothing and tell the team about current inhalers, recent illness, or difficulty performing the manoeuvre. Follow any instructions about medicines before spirometry rather than stopping treatment independently. Bring previous results if they are available, because change over time can be informative.

Arrange medical advice for worsening breathlessness, repeated low home readings, persistent wheeze, or a cough that is interfering with sleep or activity. Seek emergency help for severe breathing difficulty, blue or grey lips, confusion, fainting, or inability to speak in comfortable phrases. Testing should not postpone urgent treatment when symptoms are severe.

Ask which test is appropriate for your symptoms, whether you should monitor peak flow at home, and what changes should prompt contact. You can also ask how inhalers affect testing, whether a repeat test is needed, and when the results will be reviewed with you.