What should you know about calibrating spirometer?

A spirometer measures how much air a person moves and how quickly it moves. Calibration helps the device produce readings that can be compared with expected reference values and with later tests. Temperature, pressure, leaks, blocked filters, software settings, and worn equipment can affect performance. Calibration is different from spirometry: calibration checks the instrument, while spirometry records a person's breathing.

A trained operator follows the device manufacturer's procedure, usually using a calibration syringe or another approved reference. The check includes the correct setup, a secure connection, inspection for leaks, and documentation of the result. The operator may repeat the check when equipment is moved, serviced, exposed to unusual conditions, or gives unexpected readings. Patients should follow breathing instructions carefully and tell the operator if the mouthpiece seal is uncomfortable or they feel unwell.

Calibration is an equipment process, not a treatment. Tell the clinician before or during testing if you have chest pain, severe breathlessness, dizziness, or cannot perform the manoeuvre safely. The test may need to be paused while symptoms are assessed. A poor-quality reading should be reviewed rather than interpreted as a definite change in lung health.

Ask who performs the calibration, how the device is checked before your appointment, whether repeat blows are needed, and how the clinician will judge the quality and meaning of your spirometry results.