What should you know about volume loop spirometry?

You breathe through a mouthpiece connected to a spirometer. The device measures the amount of air you move and the speed of that movement. A volume loop displays inhalation and exhalation together, so a clinician can look at the shape as well as the recorded values. The pattern may support assessment of asthma, COPD, bronchiectasis, or an unexplained chronic cough, but it does not identify every cause of breathing difficulty by itself.

The result can be affected by effort, technique, recent illness, smoking, and medicines. Some people repeat the test after an inhaled medicine to see whether airflow changes. Feeling briefly light-headed or tired can happen after repeated forceful breaths; tell the tester if you need a pause.

Follow the clinic's instructions about inhalers and other medicines; do not stop a prescribed medicine unless the testing team tells you to. Wear comfortable clothing that does not restrict your chest or abdomen, avoid a heavy meal shortly beforehand, and avoid smoking immediately before the appointment. Bring your inhalers and a list of medicines. During the test, seal your lips around the mouthpiece, follow each instruction closely, and give a strong, complete breath when asked.

Contact a clinician promptly if breathlessness is new, worsening, or limiting ordinary activity, or if you have persistent wheezing, chest tightness, or a cough that does not settle. Seek urgent help for severe difficulty breathing, blue or grey lips, fainting, confusion, or chest pain. Do not wait for spirometry if symptoms are rapidly getting worse.

Ask what the loop pattern and measurements suggest, whether you need repeat testing, and whether your usual inhaler should be used before the appointment. Ask when you will receive the interpretation and what symptoms should prompt earlier review.