Pulmonary spirometer: what to know

The device records airflow and lung volumes. You usually sit upright, seal your lips around a mouthpiece, breathe in fully, and blow out as hard and as long as instructed. The operator may repeat the manoeuvre to check that the readings are consistent. A clinician may compare results with expected values for your age, height, and sex, while also considering your symptoms and medical history.

The test can help assess airflow obstruction and may be used when asthma or another lung problem is suspected. A reading is not a diagnosis by itself; technique, recent illness, smoking, medicines, and effort can influence the result.

Follow the clinic's instructions about inhalers, food, smoking, and strenuous activity because some medicines or activities can affect the reading. Wear comfortable clothing and tell the operator if you feel dizzy, develop chest discomfort, or cannot continue. Bring your inhalers and a current medicine list so the clinician can advise whether any should be used before testing.

The test can briefly make you light-headed or tired, but severe breathlessness, fainting, persistent chest pain, blue or grey lips, or symptoms that do not settle need urgent medical attention. Outside the testing room, seek emergency help for a sudden severe breathing attack or inability to speak normally because of breathlessness.

Ask what the measured values mean, whether the test was technically satisfactory, whether inhaler medicine changed the result, and what other assessment is needed. Ask when you should repeat the test and which symptoms require urgent help.