Lung spirometer: what the device measures

A lung spirometer measures how much air you breathe out and how quickly you can blow it out during a breathing test. The device records breaths through a mouthpiece while you follow instructions from a trained professional. Results are interpreted with your symptoms, medical history and examination rather than viewed alone.

Spirometry can show patterns suggesting narrowed airways or reduced airflow. You normally take a full breath, seal your lips around the mouthpiece and blow hard and steadily until instructed to stop. Several attempts may be needed so the team can check that the result is consistent. The related spirometry test page explains the wider diagnostic process; the spirometer is the measuring device used during it.

Wear comfortable clothing that does not restrict your chest. Follow the clinic’s instructions about meals, smoking and inhalers; some medicines may need specific timing, but do not stop a prescribed inhaler without advice. Tell the tester if you are unwell, have chest pain or recently had surgery. During the test, ask for a pause if you feel light-headed or unusually breathless.

A routine spirometry appointment is not a substitute for urgent care. Seek emergency help for severe breathlessness at rest, blue lips, fainting, confusion, severe chest pain or an inability to speak in full sentences. If coughing or wheezing is steadily worsening, contact a clinician promptly so the cause and treatment can be reviewed.

Ask what the test is assessing, whether to use your usual inhalers beforehand, how many blows are expected, when results will be discussed and whether another test may be needed to clarify the pattern.