What should you know about serial spirometry?

A spirometer records how much air you can blow out and how quickly you can blow it out. Repeating the test under comparable conditions can show whether airflow changes between visits, seasons, exposures or treatments. Results may support assessment of asthma, COPD, bronchiectasis or persistent cough, but they are interpreted alongside symptoms, examination and medical history.

A single reading can be affected by effort, technique, recent illness, smoking, medicines and time of day. A pattern across several properly performed tests can therefore be more informative than an isolated result.

Follow the clinic's instructions about inhalers, smoking, food and exercise; do not stop prescribed medicine unless the testing team tells you to. Wear comfortable clothing and tell the technician about chest pain, recent surgery, infection, dizziness or breathlessness.

During testing, you usually breathe through a mouthpiece, seal your lips around it and blow out hard and fast. Several attempts may be needed. The technician checks technique and repeatability, and may compare readings before and after an inhaler when clinically appropriate.

Tell staff immediately if testing causes chest pain, severe dizziness, faintness, marked breathlessness or wheezing that does not settle. Outside the clinic, urgent care is needed for severe breathing difficulty, blue or grey lips, confusion, or inability to speak in full sentences. A falling pattern should prompt a treatment review, not self-adjustment of inhalers.

Ask what the test is monitoring, how far apart measurements should be, which medicines to hold, how results compare with your earlier readings, and what change should trigger a review.