Pulmonary Function Tests - Children's Hospital Boston

300 Longwood Avenue
Boston, MA 02115
(617) 355-6000

My Child Has:

Pulmonary Function Tests

Programs that perform this test

	Center for Healthy Infant Lung Development (CHILD)		Cystic Fibrosis Center
	General Pulmonary Program		Lung Transplant Program
	Chronic Pulmonary and Ventilator Program

We provide pulmonary function tests in both infants and older children/ adults.

Infant Pulmonary Function Tests:

Infants are not capable of performing the voluntary breathing maneuvers necessary for measurement of lung function. Consequently, special equipment has been created to measure lung function in very young children. There is more preparation required for infant pulmonary function testing than for lung function tests in older children. The procedure is reviewed for you below, along with answers of commonly asked questions:

When are these tests done?

Your child's provider may request tests to evaluate baseline lung function as well as to any change in your child's condition. Pulmonary function testing is often used to assess lung function in patients with chronic pulmonary diseases such as Cystic Fibrosis or Bronchopulmonary dysplasia.

What happens before the test?

You will be asked not to feed your child any solid food for 6 hours before the test and no liquids for 4 hours before. These tests cause no discomfort for your child. They do require your child to be relaxed and breathe into a mask so a mild sedation is required which allows your child to 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?

The child is placed in a special Plexiglas bed and a mask is placed over his/her mouth and nose. A loose fitting jacket is placed around your child's chest and abdomen. He/she is given a few deep breaths from the mask and then the bag is inflated so it gently squeezes the chest causing him/her to blow out. This is similar to asking the older children to take a huge breath and blow out as hard as you can. For the last part of the test we measures the size of the lungs. The top of the bed is briefly closed around the child. The air coming in and out of the 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 (this is similar to measurements obtained in older children using the box.

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/she 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/her carefully to prevent any injuries from falls or bumps.

Most children will 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 should you have any questions following the test.
You can expect that your child's provider will have the results within 1 week.

Pulmonary function tests in older children and adults:

Pulmonary Function tests, also known as PFTs, are tools we use to determine the state of health of a child's lungs. Like adult Pulmonary Function Tests (PFTs), this test can provide your child's caregiver with information about how well his/her lungs are working. If your child takes medicine to help him/her breath this test may help determine how well the medicine is working.. Children 5 year of age and older begin to be capable of performing the challenging breathing maneuvers necessary for meaningful pulmonary function testing.

Pulmonary function tests are performed in Children's Pulmonary Laboratory on Farley 5.

Pulmonary function tests always include spirometry. Spirometry is a test that measures the volume of air that can be exhaled from the lung after the child breathes in their largest possible breath. Spirometry also measures how fast the air comes out (the flow). To perform this test, a patient is asked to place his mouth around a cardboard mouthpiece on a long tube attached to our computers. The patient also puts on a nose-clip to prevent air from leaking out the nose during the test. The patient will first begin by breathing quietly through the mouthpiece. He/ she will then be instructed to take in the biggest breath possible, and then blow it out as hard, as fast, and as long as possible. The computer measures he amount of air breathed out over time.

Another important value is the Total Lung Capacity (TLC), which is a measurement of the total amount of air a patient's lungs can hold. This measurement is performed in a body plethysmograph, or "the Box." The box is a clear Plexiglas booth, similar to a telephone booth. The patient sits inside the booth and breathes into a tube in a manner similar to spirometry, and again the tube attached to a computer. The computer then calculates the patient's lung volume.

Another important test we perform measures the amount of oxygen and carbon dioxide in the blood. The simplest test is the oxygen saturation. This is a routine test in which a small red light is placed on the bed of the fingernail; the light gives us a way to measure the amount of oxygen in the blood without using a needle. However, to get more detailed information, a sample of the blood is needed. This test, called an arterial blood gas, involves drawing blood from an artery in the wrist. We then measure the amount of oxygen and carbon dioxide in the arterial blood to determine how well the lungs are working.

The above outlined tests are the most common tests performed in this lab; however, we also perform tests to measure respiratory muscle strength, to determine responsiveness to inhaled medications, to evaluate responsiveness to cold air and exercise. Infant pulmonary function tests are also available.



	The information on this website should not be taken as medical advice, which can only be given to you by your personal health care professional.

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