If you have a child with asthma, you probably know that their symptoms can vary for many reasons. One way to help assess your child’s asthma is a lung function test. A lung function test (spirometry) evaluates how well your lungs work – how much air you can breathe in, how much air you can blow out and how quickly you can do it. The test consists of breathing into a mouthpiece that is hooked up to a computer. To take the test correctly, you must take a big breath until you can’t inhale any further and then blow out as hard and fast as you can until no further air comes out of your chest. Because this is hard for young children to do, the test is usually not given to children who are under 6 years of age.
For children 6 years of age or older with asthma, spirometry is the lung function test most commonly used. The National Heart Lung and Blood Institute (NHLBI) recommends that children with asthma who are old enough to follow the instructions perform the test yearly to help your doctor understand your child’s asthma. This is because spirometry can provide different kinds of information:
If your child is doing well and the spirometry testing shows that the lungs are working normally, this is good news, but it does not mean that your child no longer has asthma. Instead it tells us that your child’s lungs are working about as well as his or her peers, despite the asthma. You may see normal testing in a child with asthma because the symptoms may come and go. Some children may only experience asthma symptoms during head colds, or during allergy season, or perhaps only during exercise. In other children, asthma symptoms are present more often than they are not, even in the absence of head colds or allergy season.
For children whose spirometry testing shows that their lungs are not working as well as their peers, the spirometry results can help guide your doctor to adjust your child’s medications and to decide on a reasonable follow-up interval for the next planned asthma visit. If changes are required in your child’s treatment plan (either increases or decreases to medications), your doctor may decide to repeat the spirometry in a few months to see how your child is reacting to that change of treatment. Spirometry may also be repeated after environmental triggers (such as dust mites, mold or pet dander) have been eliminated, in order to gauge how effective those changes have been in improving your child’s asthma.
For children with asthma whose lung function testing is normal, you and your child’s doctor still need to pay close attention to other indicators that the asthma is not as well controlled as it should be. Some symptoms to look for are:
Lung function testing can help you and your child’s doctor better understand how asthma may be affecting your child. This testing may help to identify the need to change medications or to address environmental triggers in order to help your child keep his asthma in control. If your child has asthma, is older than 6, and has not had a spirometry test in the last year, you should speak with your child’s doctor about whether your child should have a spirometry test.