What should you know about spirometry?

You breathe into a spirometer through a clean mouthpiece. The device records measurements such as the air blown out in the first part of a forceful breath and the total amount exhaled. The clinician may repeat the test after a bronchodilator inhaler to see whether airflow changes. Results are interpreted alongside your symptoms, examination and medical history; one reading does not explain every cause of breathlessness.

Spirometry can support assessment of asthma, COPD and some other airway problems. It may also help investigate a persistent cough or monitor breathing over time. A spirometer is the device used for this measurement.

Wear comfortable clothing and avoid a heavy meal shortly before the appointment. Follow the clinic's instructions about inhalers, because some medicines may need to be paused while others should be taken as usual. Do not stop prescribed treatment without advice. During the test, sit upright, seal your lips around the mouthpiece and follow the coaching closely; a strong, complete effort helps produce a useful result.

Contact a clinician if ongoing cough, wheeze, chest tightness or breathlessness is affecting daily activities, waking you, or changing from your usual pattern. Seek urgent help for severe breathing difficulty, blue or grey lips, fainting, confusion, or chest pain that is severe or persistent. Spirometry is usually planned when you are well enough to perform it; tell the service if your breathing has suddenly worsened.

Ask which medicines to use before testing, whether your results suggest a particular airflow pattern, and when you will discuss them. You can also ask whether repeat testing, inhaler therapy, or help to stop smoking would be useful for your situation.