Pulmonary Function Test

What is a Pulmonary Function Test (PFT)? 

A pulmonary function test (PFT) is a type of test that evaluates your child’s lung function and can measure changes in your child’s pulmonary condition. If your child has been diagnosed with a chronic pulmonary disease such as cystic fibrosis or bronchopulmonary dysplasia, their pediatrician will likely recommend they receive a pulmonary function test (PFT) to assess how their lungs are functioning. If your child is over the age of 5, they should be able to perform breathing maneuvers needed for PFT testing however, there is special equipment PFT can involve various types of tests. These tests include: 

  • Total lung capacity (TLC) Test: This type of lung test measures how much air your child’s lungs can hold. For this test, your child will be placed in a clear Plexiglas booth that is called ‘plethysmograph’ or “the box”. 
  • Spirometry test: A spirometry test is a PFT that measures how much air your child can exhale from their lungs after they have taken the largest breath they could take. Spirometry tests also measure how fast air comes out when they release that breath. This can also be referred to as ‘the flow speed’. 
  • Oxygen saturation: This is the simplest form of PFT there is! It measures the amount of oxygen and carbon dioxide in your child’s blood. For this test, a small red light will be placed on your child’s fingernail. This light will measure how much oxygen is in the blood without the use of a needle. 
  • Arterial blood gas: For more detailed information regarding your child’s lung function, they may need to have a blood test done. The arterial blood gas test involves drawing your child’s blood from their wrist which will determine the amount of oxygen and carbon dioxide in their blood. This will help determine how well your child’s lungs are working. 

Although these are the most common tests to measure your child’s lung function, your child’s pediatrician may perform tests to: 

  • Determine respiratory muscle strength.
  • Evaluate responsiveness to medications.
  • Measure lung responsiveness to exercise and cold air. 


How to prepare your child for a PFT?

When your child is scheduled for a Pulmonary Function Test, we will ask that you do not feed them any solids 6 hours before the test or any liquids 4 hours before the test. These tests are not known to cause discomfort, however, they do require that your child remains relaxed as they will need to breathe into a mask. A mild sedative will be given to your child which will allow them to sleep through the entire procedure. Typically, these procedures do not take longer than 50 minutes. 


What happens after a Pulmonary Function Test (PFT)? 

After your child has woken up for their PFT, they will likely be thirsty. Once they can drink well, they will be free to leave. Keep in mind that your child may be uncoordinated for the day so they must be observed to prevent any injuries. It is common for children to become tired and want to nap for the rest of the day but they should quickly return to their normal sleep schedule that night. Parents will also be given special discharge care instructions as well as a number to call in case questions arise. You should expect your child’s results within a week of the test. 


At the office of Dr. Alfonso J. Henriquez, our priority is to assure your child receives the care they deserve. If you have concerns regarding your child’s health or would like to schedule an appointment to discuss pulmonary function tests, Please contact us.