Pulmonary function test (PFT)
When are these tests done?
Your child's doctor may request tests in order to evaluate baseline your child’s lung function or to measure any change in your child's condition. Pulmonary function testing is often used to assess lung function if your child has a chronic pulmonary disease, such as cystic fibrosis or bronchopulmonary dysplasia.
What happens before the test?
We ask that you not feed your child any solid food for six hours before the test and any liquids for four hours before.
These tests cause no discomfort. They do require him to be relaxed and breathe into a mask, so we will give him a mild sedative which will let him sleep through the entire procedure. The medicine used for sedation is called chloral hydrate and is administered by mouth. Once your child is asleep, the test takes about 50 minutes.
How are these tests done?
Your child is placed in a special Plexiglas bed and a mask is placed over his mouth and nose. A loose fitting jacket is placed around his chest and stomach. He is given a few deep breaths from the mask and then the bag is inflated so it gently squeezes the chest causing him to blow out. This is similar to asking the older children to take a huge breath and blow out as hard as they can.
For the last part of the test, we measure the size of your child’s lungs. The air coming in and out of your child's lungs is stopped for a few seconds, which causes a pressure change in the box and enables the computer to calculate lung size.
What happens after the test?
We will wake your child up immediately following the test. Most children wake up easily and are eager for something to drink. Once he is drinking well, you will be free to leave the lab. Your child may be a bit floppy and uncoordinated the better part of the day and it is important to watch him carefully to prevent any injuries from falls. Most children nap off and on the rest of the day and return to their normal sleep pattern that night.
You will be given special discharge instructions as well as a number to call in case you have any questions after the test. Your child's provider will have the results of the test within a week.