Teens with Cystic Fibrosis-Pulmonary
Function and Airway Clearance

Growing up with CF has many challenges; taking care of your CF may be one of the hardest parts about being a teenager. Because you grow so much during puberty you can and should expect your lungs to grow too. While you are using energy to grow and increase your lung volumes, your body also needs a lot of energy and help from you to fight CF.


Spirometry is performed at each (quarterly) CF visit. The spirometer records the amount of air that you breathe in and blow out and how quickly you are able to expel the air from your lungs. Normal values are based on your age, height, ethnicity and sex. Normal results are expressed as a percentage. A value is usually considered abnormal if it is less than 80% of the predicted value.

The forced expiratory volume (FEV1) is a measurement of the amount of air you are able to force out in the first second of exhalation. The FEV1 is recognized as a predictor of progression of lung disease. A value of 10% below your personal baseline often indicates an infection or decline of your CF, and the need for changes or treatment. It is expected that a person with CF will experience a drop of 1-2% of their FEV1 each year due to the effects of lung damage.

Pulmonary Function Test

Once a year as part of your “annuals”, a more comprehensive measurement called full pulmonary function testing (full PFT’s) is recommended by the Cystic Fibrosis Foundation. PFT’s are a group of tests that measure how well your lungs take in and release air before and after a bronchodilator (such as Albuterol) and how well they move gasses like oxygen from the air into the body’s circulation. This test is done in the Diagnostic Study area of the Children’s Hospital.

Airway Clearance

Lots of thick mucus is produced in the lungs of people with cystic fibrosis. This leads to frequent infection (with bacteria and virus’), inflammation (swelling), and tissue damage. It is important to clear this mucus using medications and various airway clearance techniques and devices. Treatments which help with the thinning and removal of mucous are very important to help preserve (save) your lung function and reduce the permanent damage to the lungs caused by CF

There are many different types of airway clearance methods. Conventional chest physiotherapy (CPT) usually requires the assistance of another person. Self administered airway clearance techniques include: high frequency chest compression (HFCC, The Vest), Intrapulmonary percussive ventilation (IPV), the active cycle of breathing technique (ACBT), autogenic drainage (AD), positive expiratory pressure (PEP), Flutter and Acapella. Please plan to perform aerosol and clearance therapy two times a day unless you are told differently by your CF doctor. Please contact your CF center respiratory therapist to find a method that works well for you.