Pulmonary Function Testing

Pulmonary function tests help measure how well your child’s lungs are working. They are useful for diagnosing asthma and other conditions related to the lungs.

Explain to your child before the test that:

• There will be no pain
• The test is meant to find out how to help them breathe better

It can be helpful to present the test as a game, where the child must blow through a horn like it’s a toy or an instrument.

Don’t give your child any medicines that will change how they breathe before they take the test. Taking medicine prior to the test could make the test less effective. Tests should not be given to children who have certain types of heart disease, or have recently suffered a collapsed lung. Don’t feed your child a heavy meal before the test.

Each test is different. A respiratory therapist or technician will help you and your child perform the test correctly. It may take several tries to get the correct measurements.

Results are available shortly after the test is conducted.

Pulmonary function tests may need to be done several times. Sometimes they need to be done at one time; sometimes they need to be done over a period of time to monitor changes and determine if treatment or medicine is working. Speak to your health care professional about the need for multiple tests.

Pulmonary (lung) function tests help your child’s doctor diagnose a lung condition, check your child’s response to treatment, and measure your child’s condition over time. There are several different kinds of pulmonary function tests. These include:

• Breathing tests measure the size of your lungs, how much air you can breathe in and out, and how fast you can breathe air out. Examples include spirometry [spy-ROM-uh-tree] and lung volume measurement.
• Oxygen level tests assess how well your lungs deliver oxygen to your child’s bloodstream. For example, pulse oximetry (also called pulse ox) uses a special light clipped to your child’s finger (or taped to a foot) to measure the oxygen in their blood.
• Exercise tests are sometimes combined with oxygen level tests. They help your child’s doctor to understand how your child’s heart and lungs respond to the stress of physical activity. They can also help the doctor figure out the severity of your child’s condition.

Some common breathing tests include:

• Spirometry to measure how much air your child inhales and exhales, as well as how quickly they do so.
• Lung volume tests to measure how much air your child’s lungs can hold.
• Pulse oximetry to measure the level of oxygen in your child’s blood.
• Lung diffusion capacity to see how well oxygen is moved into your child’s blood in the lungs.
• Blood gas tests check the gases (oxygen and carbon dioxide) in your child’s blood.
• Nitric oxide tests measure the amount of nitric oxide your child breathes out.

Pulmonary function tests have few side effects and do not cause any pain.

Pulmonary function tests, especially spirometry, might be frustrating for your child. Sometimes multiple attempts need to be made before the test works correctly. The test may cause coughing, lightheadedness, shortness of breath, or fatigue. The test will not be painful and will not have any lasting side effects.