Lung Function Tests: Spirometry

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KEY POINTS

• Lung function tests measure how well your child’s lungs are working. A test called spirometry measures how much and how fast air can move out of your child’s lungs.
• These tests can help find lung problems such as asthma. The tests can also help find the best treatment plan for your child, and check how much better the lungs work when your child is given medicine.
• Talk to your healthcare provider about what the test results mean and ask any questions you have.

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What is spirometry?

Lung function tests measure how well your child’s lungs are working. A test called spirometry measures how much and how fast air can move out of your child’s lungs.

Why is it done?

Spirometry can help:

• Diagnose lung diseases such as asthma, chronic bronchitis, and emphysema
• Find the cause of shortness of breath
• Measure the effects of exposure to cigarette smoke, chemicals, coal dust, and other toxins that can damage lung function
• Measure how well the lungs are working
• Find the best treatment plan for your child
• Measure how much better the lungs are working when medicines are given for narrowed airways

How do I prepare my child for these tests?

Often no preparation is needed. If your child has asthma, ask the healthcare provider if your child needs to stop using asthma medicine before the test. Follow the provider’s instructions about eating and drinking before your child’s test.

How is spirometry done?

Your child will breathe into a mouthpiece that is connected to an instrument called a spirometer. The spirometer measures the volume of air that your child can force out of his lungs in 1 second after having inhaled as much air as he can. Your child will be asked to hold the mouthpiece tightly with his lips, breathe in as much air as possible, and then blow out as hard as he can into the spirometer until his lungs feel completely empty. The amount of air your child can force out in the first second is called forced expiratory volume, or FEV1. The total amount of air your child can force out is called forced vital capacity.

The test is not painful, and your child will have time to rest between tests. The test may be repeated 2 or more times.

Ask your child’s healthcare provider when and how you will get the test results.

What do the test results mean?

The test results help your child’s healthcare provider know how well your child’s lungs are working. If the test results are not normal, this test can help your child’s healthcare provider determine what kind of lung disease your child may have and how severe it is.

Ask your child’s healthcare provider any questions you have about your child’s test results.

What if my child’s test results are not normal?

Test results are only one part of a larger picture that takes into account your child’s medical history and current health. Sometimes a test needs to be repeated to check the first result. Talk to your healthcare provider about your child’s results and ask questions, such as:

• If your child needs more tests
• What kind of treatment your child might need
• What lifestyle, diet, or other changes your child might need to make