Insensitive spirometer: what to know

A spirometer measures how much air you breathe out and how quickly you can exhale. If the device appears not to respond, gives an unexpectedly low result, or shows little change between attempts, the cause may be a loose mouth seal, hesitation, coughing, an incomplete breath in, or a sensor or software problem. Airway narrowing can also limit the result. One reading cannot by itself diagnose or exclude a lung condition.

Tell the tester exactly what felt unusual. Sit upright, follow the demonstration, seal your lips firmly around the mouthpiece, inhale fully, and blow out hard and continuously for as long as instructed. Avoid blocking the mouthpiece with your tongue. The clinician may check the tubing and calibration, coach another attempt, or repeat the test after rest. Do not change inhalers unless the prescribing clinician gives a clear instruction.

Contact the testing service if the result was technically difficult or does not match your symptoms. Seek urgent medical help for severe breathlessness at rest, blue or grey lips, chest pain, fainting, or difficulty speaking in full sentences. A clinician may use formal spirometry, inhaler response testing, peak-flow readings, or other assessments when the initial test is inconclusive.

Ask whether the test met quality standards, whether your inhaler should be withheld before repeat testing, and whether the pattern suggests obstruction, restriction, or a technique problem. Ask when you will receive the interpreted report.