How to use a spirometry machine

Spirometry depends on a strong start, a complete breath out and a good seal around the mouthpiece. Coughing, hesitation, stopping early or leaking air can change the recording. The operator may coach you and ask for repeat attempts so the measurements can be compared. The test measures breathing performance at that appointment; it does not describe every change that might occur between visits. Your clinician interprets the values with your symptoms and medical background.

Follow the appointment instructions about food, exercise and inhalers. Sit upright if advised, keep the mouthpiece clear, inhale fully, and blow out hard until the operator says to stop. Rest between attempts when asked. Tell the team if you feel unwell, have had recent chest surgery or cannot maintain the required effort. Do not alter the machine or use a home device to change prescribed treatment. Read more about [Spirometry](/treatments/diagnostics-and-screening/spirometry/) and [Inhaler Therapy](/treatments/medical-management/inhaler-therapy/).

Tell the operator straight away about chest pain, faintness or a sharp increase in breathlessness. Emergency help is appropriate for severe breathing difficulty, blue or grey lips, confusion, collapse or inability to speak normally. A test appointment should not delay care for an acute attack. If cough or wheeze keeps returning, arrange an assessment; information about [Asthma](/conditions/asthma/) may help you prepare.

Ask how to prepare, which medicines affect the appointment, how many attempts may be needed, and when the result will be explained. Confirm what symptoms should trigger an earlier review.