What should you know about IOS spirometry?

IOS usually refers to impulse oscillometry. It uses gentle pressure waves sent through a mouthpiece while you breathe quietly. The device analyses how the airways respond to those waves. This can provide information about resistance in the larger and smaller airways without requiring repeated forceful blows.

The test may help a clinician assess narrowing, obstruction, or changes in airway function. Results can be considered alongside your symptoms, examination, oxygen level, medical history, and other tests. IOS may be useful when a person finds standard spirometry difficult, although the two tests measure breathing in different ways.

Standard spirometry generally asks you to inhale fully and exhale as hard and fast as possible into a spirometer. IOS focuses on the movement of pressure waves during quiet breathing. An abnormal result does not identify one condition by itself; asthma, COPD, bronchiectasis, and other airway problems can require different forms of assessment.

Follow the testing centre’s instructions about meals, smoking, exercise, and inhalers. Some medicines may need to be paused before testing, but only change them when the clinician arranging the test tells you to. Wear clothing that allows your chest and abdomen to move comfortably.

During the assessment, you will sit upright, seal your lips around a mouthpiece, and breathe as instructed. A nose clip may be used so air does not escape through your nose. Tell the clinician if you feel dizzy, breathless, or uncomfortable. Ask when and how the report will be explained, especially if the test is being used to monitor asthma or another long-term airway condition.

Arrange medical advice for new or persistent wheezing, breathlessness, a cough that does not settle, chest tightness, or reduced ability to manage usual activity. A test should support an assessment; it should not delay care when symptoms are worsening.

Seek urgent help for severe difficulty breathing, blue or grey lips, confusion, fainting, inability to speak in full sentences, or rapidly worsening symptoms. If you have a prescribed reliever inhaler and it is not helping as instructed, use local emergency services or urgent medical care.

Ask what the test is intended to investigate, whether you also need standard spirometry or another breathing test, and whether any inhaler or other medicine should be withheld beforehand. You can also ask which result will be reviewed, when it will be available, and what symptoms should prompt earlier contact.