ATS 2019 spirometry: what patients should know

Spirometry measures how much air you can force out after a full breath and how quickly you can expel it. A trained operator explains the manoeuvre, applies a nose clip if appropriate, and asks you to seal your lips around a mouthpiece. You then inhale fully and blow out hard and continuously until told to stop. Several attempts are usually needed so the operator can check that the efforts agree and meet quality criteria.

Results are interpreted alongside age, sex, height, symptoms and clinical history. A pattern can suggest narrowed airways or reduced lung capacity, but spirometry alone does not name every cause. Sometimes the test is repeated after an inhaled bronchodilator to see whether airflow changes.

Follow the clinic's instructions about inhalers because whether to pause them depends on the purpose of the test and the medicine involved. Wear loose clothing, avoid a heavy meal immediately beforehand and tell the operator about recent chest infection, surgery, coughing blood, fainting with forced breathing, pregnancy or a heart problem. Bring your inhalers and medication list.

Give a firm effort but listen closely to coaching; technique affects the tracing. If an attempt is interrupted by coughing, a poor mouth seal or stopping early, it may simply need repeating. Ask when and how the interpreted report will be discussed rather than trying to diagnose yourself from a single number.

Tell the operator immediately if you develop chest pain, severe breathlessness, marked dizziness, weakness or feel close to fainting during the manoeuvre; the test should be paused and you should be assessed. Outside the clinic, sudden severe breathing difficulty, blue or grey lips, confusion, collapse or chest pain needs emergency help regardless of any planned spirometry appointment.

Ask whether the efforts met quality standards, what pattern was seen and whether a bronchodilator changed the measurements. Clarify how the findings fit your cough, wheeze or breathlessness, whether more testing is needed, and whether the result changes inhaler use, smoking-cessation support or follow-up.