What is spirometry?
Spirometry is a breathing test that measures lung function by having the child take a deep breath in and then blow out as hard and fast as possible into a mouthpiece connected to a sensor. It produces objective numbers — how much air was exhaled, and how quickly — that show whether the airways are narrowed, and by how much, rather than relying on how breathing sounds or feels.
Why it matters for asthma
Symptoms alone don't always reflect how well-controlled a child's asthma actually is — some children under-report breathlessness they've adapted to. Spirometry gives a baseline reading and can be repeated over time to track whether treatment is working, confirm a diagnosis, or spot silent airway narrowing before it becomes symptomatic.
How the test is done
- The child breathes into a disposable mouthpiece connected to a spirometer
- They take a full deep breath in, then blow out as hard and fast as possible until told to stop
- This is repeated a few times to get consistent, reliable readings
- Sometimes repeated again after an inhaler to see how much the airways open up in response — useful for confirming asthma
Age & preparation
Spirometry needs the child to understand and cooperate with forceful breathing instructions, so it's generally reliable from around 5–6 years of age onward, though this varies by child. Avoid a heavy meal right before the test, and any specific instructions about pausing reliever inhaler use beforehand will be given ahead of the visit.
Talk to Dr. Narwani: Whether this test or treatment is right for your child depends on their specific history and prior test results — book a consultation to discuss.