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Pulmonary Function Tests (PFTs)

This information describes why pulmonary function tests (PFTs) are performed and what to expect before, during, and after your test.
 
PFTs are breathing tests that measure how your lungs are working. The results will show how much air your lungs can take in and how the air flows in your lungs. PFTs take about 45 minutes to 1 hour. Your doctor mayrequest a complete test or only parts of the test.
 

Reasons For Having PFTs

PFTs may be performed to see how the lungs are working before surgery, diagnose or evaluate lung disease, or monitor the side effects of cancer treatment.
 

Before surgery, PFT may be done to:

  • See if there are issues with your lungs that could interfere with anesthesia (the medications used to make you sleepy).
  •  See how much air your lungs can hold.

PFTs may be done to help your doctor:

  • Diagnose lung disease
  • Diagnose abnormal functioning of the lung
  • Determine the amount of damage caused by abnormal lung functioning
  • Check the status of chronic (long-term) lung disease
    • The two major patterns of lung disease are obstructive and restrictive. In obstructive lung disease there is a decrease in the flow of air. Examples include emphysema or asthma. In restrictive lung disease the amount of air the lung can fill up with is limited. Examples are fibrosis or scarring.

PFTs may be used to monitor the side effects of cancer treatment, such as:

  • Radiation in the area of your lung(s)
  • Some chemotherapy drugs

Preparing For Your PFTs

On the day of and prior to your PFTs:

  • Do not eat a large meal. If you feel hungry, eat a light meal.
  • Do not have any caffeine, such as coffee, tea, or chocolate, for 4 hours prior to your test.
  • Please arrive on time for your appointment.
  • Write any additional instructions from your healthcare provider here:

During Your PFTs

A pulmonary technologist perform your PFTs. You will sit in a pulmonary analyzer, a machine that will record the amount, force, and pattern of your breath. You will wear a nose clip to keep air from going through your nose while you blow into a mouthpiece. Your technologist will tell you to take deep, shallow, slow, or rapid breaths at different periods during the test.
 
The effort you make can have a big influence on the results of the test. You will be asked to repeat sections of the test to get the best results. You may be asked to inhale a medication called a bronchodilator to open your airways. Inhaling a bronchodilator will help your doctor determine if you might benefit from specific medication(s).
 

Arterial Blood Gas Test

You may have some blood drawn to measure the amount of oxygen and carbon dioxide in your blood. This is called an arterial blood gas test. It is the only part of the PFTs that may hurt. If you have an arterial blood gas test, medication will be used to numb your wrist, then blood will be removed from your radial artery. After the blood is drawn, an elastic bandage will be put on your wrist. Wait 4 hours before you remove the bandage.
 

After Your PFTs

  • If you had blood drawn for the arterial blood gases test, keep the elastic bandage on for at least 4 hours after your test. You may feel some tingling or numbness at the site. This should only last until the next morning.
  • You may go back to your regular diet.
  • There are no restrictions on your activities.
  • Your healthcare provider will explain the results of your test and what it means for your overall care. If you have any questions or concerns, please talk with your doctor or nurse.