Pulmonary Function Laboratory
Tests Offered

Tests Performed by the Pulmonary Function Laboratory

The Pulmonary Function Laboratory at Cincinnati Children’s can conduct a number of tests to measure respiratory health. We coordinate with your child’s pediatrician to perform the tests and evaluate the results. Each test involves a different procedure and measures different aspects of your child’s pulmonary function. All testing is overseen by a physician. Your child’s test will be interpreted by a pediatric pulmonary physician and a report will be sent to your doctor.

What are Pulmonary Function Tests (PFTs)

Pulmonary Function Tests measure how well the lungs breathe in air.

PFTs can be used to:

  • Identify if your child or infant has a decrease in lung function
  • Measure the effects of known chronic lung diseases – such as asthma and cystic fibrosis – on your child’s lung function. Asthma tests include Exhaled Nitric Oxide (eNO), Exercise Induced Asthma Test and Methacholine Challenge Test
  • Decide if medication is needed or needs to be adjusted
  • Serve as pre-surgery testing to determine your child’s ability to tolerate medical procedures
  • Determine if intense exercise decreases your child’s lung function


Watch a video about spirometry

This test measures how much and how fast air flows into and out of the lungs. Your child will be asked to breathe out as hard and for as long as possible into a measuring device. The test takes only a few minutes, although a complete session, with explanations and practice testing, may take up to 40 minutes. Spirometry testing is sometimes done in conjunction with other tests, such as the lung volume test (plethysmography).

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Watch a video about plethysmography

This test measures how much air your child’s lungs hold.  Your child will sit in an enclosed Plexiglass chamber and will breathe through a mouthpiece according to the therapist’s instructions. The test is done in conjunction with a spirometry test, and takes about 40 to 60 minutes to complete.

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Watch a video about the diffusion test

This test measures the transfer of gases in your child’s lungs. It can help indicate the lungs’ ability to transfer oxygen into the bloodstream. The test involves your child breathing through a mouthpiece connected to a computerized monitoring machine. It is performed with other tests, and could take up to an hour to complete. Your child’s pediatrician may limit eating, exercise and smoking prior to the test.

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Watch a video about the methacholine challenges test.

This test is used by your child’s pediatrician to determine if your child has asthma. The therapist will have your child inhale a very low dose of methacholine, a drug that may cause the airway to narrow. Using spirometry tests, the therapist will measure your child’s breathing after gradually increasing doses of methacholine. The therapist will closely monitor your child and can give your child a quick-acting treatment if necessary. This test takes up to two hours.

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Watch a video about the exercise induced asthma test

In this test, your child will first breathe into a spirometer to measure airflow rate. Your child will exercise on a treadmill to reach a target heart rate. The therapist will measure heart rate, and blood oxygen levels during the exercise, and will ask your child to rate their level of exertion. After the run, your child will complete spirometry tests every five minutes for 30 minutes, to measure lung function after exercise. Your child should not eat three hours before the test, and your child’s physician may have your child stop taking certain medications prior to the test. This test lasts about 90 minutes to two hours.

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Watch a video about respiratory muscle strength test

This testing involves three separate tests that measure the strength of the muscles your child uses to breathe. The Maximal Inspiratory Pressure (MIP) test measures the strength of muscles used to take in deep breaths. The Maximal Expiratory Pressure (MEP) test measures the muscles used to cough. And the Maximum Voluntary Ventilation (MVV) measures both sets of muscles together and gives the therapist an idea of how well your child can breathe in and out. The tests usually take less than 20 minutes.

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