What is a Pulmonary Function Test?
A Pulmonary Function Test is actually a series of tests that the physician uses to determine how well your lungs are functioning. It measures the quantity of air you move, how well you move the air, and how well your lungs work at exchanging oxygen and other gases in and out of your bloodstream. Sometimes a bronchodilator is used to open airways allowing for better air movement. For some tests different gases are given through the tubing to measure different lung functions or areas.
Why is a Pulmonary Function Test Required?
Pulmonary Function Tests help the physician evaluate the patient's overall pulmonary status in regards to:
- Evaluating an existing asthmatic condition or determining if the patient has asthma.
- Evaluating an existing COPD condition or determining if the patient has COPD (Chronic Obstructive Pulmonary Disease, or COPD, is a term used for a combination of chronic bronchitis, emphysema and asthma).
- Work related conditions resulting from inhaling fumes such as paint, welding gases etc.
What is involved in Preparation?
- Do not eat a large meal before the test
- Do not smoke at least 2 hours before the test
- If you take any bronchodilators such as Albuterol, try to wait until the test time.
- Wear comfortable clothing.
What is Expected Once I Arrive for the Test?
- Once you arrive and register, a Respiratory Therapist will escort you back to the PFT Lab.
- You will be measured for accurate height and weight and your vital information will be entered into the computer. For some of the tests you will be seated outside a box, for some of the tests you will be seated inside the box with the door shut. Please let the therapist know if you are claustrophobic or uncomfortable in any way.
- For the performance of all of the tests, you will need to put forth your best effort. A test will come back abnormal if complete effort is not given causing the therapist to dismiss the test and have you perform it again. This can become very tiring and frustrating.
- Be sure to rest in between tests. To try to "just get it over with" may also lead to quick fatigue and abnormal test results.
- If the physician requests the tests be done "before and after bronchodilator", once you have performed each of the tests you will be given a medication called a bronchodilator to relax and open your airways. After a 10-15 minute wait you will be asked to complete the tests again to see if your airways perform better.
- Some of the various tests that the physician will order are:
- Spirometery -- This is a simple test that measures how forcefully you can inhale and exhale taking in as large a breath as possible. Three comparable efforts are needed for this test. Your best effort is needed in this test so the results do not come back abnormal simply because you are not trying hard enough.
- Diffusion Capacity -- This test measures your lung's efficiency of delivering oxygen and other gases to your bloodstream. You will be instructed to breathe in a small amount of carbon monoxide*, the amount you exhale will then be measured and compared to the amount inhaled. Your ability to absorb carbon monoxide reflects your ability to absorb other gases such as oxygen.
* The amount of carbon monoxide is too small to cause any harm.
- Lung Volume -- This test measures lung size by having you inhale a small amount of gas such as helium or nitrogen*. The gas mixes with the air in your lungs before you exhale. The mixture is then analyzed to determine how much gas the air in your lungs diluted. A calculation is then used to determine how much air is held in your lungs at all times.
* This gas is not absorbed into your bloodstream.
- Plethysmography -- For this test you will be required to sit inside of an airtight box similar to an enclosed golf cart. You will be instructed to inhale and exhale through a mouthpiece connected to the outside via a tube. The air pressure changes as you perform different breathing maneuvers because your chest expands and contracts as you breathe. These pressure changes are then measured and calculated to determine the amount of air you must be breathing.
- A physician must order this test.
- This test must be scheduled through Cardiopulmonary Diagnostics.
- Bring the order with you and register at the registration desk between Lab and Cardiopulmonary Diagnostics.
When Will I Know the Results of the Test?
If there is a Pulmonologist at the clinic ordering the PFT, the results will be available that same day. Otherwise a physician will have it read by the next day.