Pneumotach spirometer: what to know

A pneumotach uses a flow sensor to detect how quickly air moves in and out. Software turns that airflow into measurements such as the amount of air exhaled and the speed of exhalation. The test can help assess asthma, chronic obstructive pulmonary disease and other breathing concerns, but the device does not identify a diagnosis by itself. Results are interpreted with your symptoms, examination and medical history. A nose clip may be used so air passes through the mouthpiece, and the test usually involves repeated coached efforts.

Wear comfortable clothing and follow the clinic's instructions about meals, smoking, exercise and inhalers. Tell the tester if you feel dizzy, have chest pain, or cannot produce a strong breath. Sit upright, seal your lips around the mouthpiece and follow each instruction closely; effort and technique affect the reading. Some tests compare breathing before and after an inhaled medicine, so ask whether to use your usual inhalers beforehand. Bring a list of medicines and recent respiratory symptoms.

Tell the clinician immediately if the manoeuvres cause chest pain, severe breathlessness, faintness or wheezing that does not settle with rest. Seek urgent care for severe breathing difficulty, blue or grey lips, confusion or inability to stay awake after leaving the test. A test appointment should not delay emergency treatment for an acute breathing problem.

Ask what the test is intended to clarify, whether you should change any inhaler before attending, how many efforts are expected, and when the results will be discussed. Ask what follow-up is needed if the readings do not match your symptoms.