What should you know about flow volume spirometry?

You breathe into a mouthpiece connected to a spirometer. The device records airflow as you breathe in and blow out, often producing a loop-shaped graph. The shape can suggest narrowed airways, while the measured volumes help the clinician judge how fully you emptied your lungs. Results are interpreted alongside your symptoms, examination and medical history; one graph does not identify a condition on its own.

The test may be used when asthma, COPD, bronchiectasis or a persistent cough is being assessed. A repeat reading after prescribed inhaler medicine can show whether airflow changes.

Wear comfortable clothing and follow the clinic's instructions about food, smoking and medicines. Tell the clinician if you are unwell, have chest pain, feel dizzy during exertion, or have recently had surgery. During the test, seal your lips around the mouthpiece, breathe as instructed and make a strong, sustained blow. Several attempts are normal because technique affects the tracing.

Bring your inhalers or a list of medicines. Do not stop treatment unless the testing team specifically tells you to.

Arrange medical assessment for breathlessness that is new, worsening or limiting ordinary activity, especially with wheezing, chest tightness or a cough that does not settle. Seek urgent help for severe breathing difficulty, blue or grey lips, fainting, confusion, or inability to speak in full sentences. If the test makes you light-headed, stop and tell the clinician; symptoms usually improve with rest.

Ask what the main measurements and loop pattern mean, whether the result suggests airflow narrowing, and whether you need repeat testing. You can also ask how to use your inhaler correctly, whether smoking cessation support could help, and what symptoms should prompt an urgent review.