What Is a Spirometer Used For?

A spirometer is a small machine with a disposable mouthpiece. You breathe into it while the device records airflow and volume. The results can show whether air leaves the lungs more slowly than expected, whether the amount exhaled is reduced, and whether airflow changes after an inhaled medicine. Clinicians interpret the pattern alongside symptoms, examination findings, age, height and other health details.

The device does not diagnose every breathing problem by itself. It is used in spirometry, which may help assess asthma, chronic obstructive pulmonary disease and other causes of cough, wheeze or breathlessness. It can also monitor lung function over time or check breathing before certain procedures.

You normally sit upright, seal your lips around the mouthpiece and follow clear instructions. A nose clip may be used so air does not escape through your nose. You take a full breath, then blow out hard and steadily until asked to stop. The manoeuvre is repeated to check that the readings are consistent. Wear comfortable clothing and tell the testing team if you feel dizzy, have chest pain or recently had an illness or procedure that affects breathing.

Tell the clinician immediately if testing brings on severe breathlessness, chest pain, faintness or wheezing that does not settle with your usual prescribed treatment. Seek urgent help for sudden severe breathing difficulty, blue-grey lips, confusion or collapse. Do not force repeated blows at home to test yourself.

Ask what the test is checking, whether to pause any inhalers beforehand, how many blows will be needed, whether a bronchodilator will be used and when the results will be reviewed.