Pulmonary Function Tests: Procedure, Time, and How to Prepare

Pulmonary function tests help assess your lung health and diagnose respiratory issues. Read on to learn more about the test and how to prepare effectively.

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How Is a Pulmonary Function Test Done? Step-by-Step Guide

Pulmonary function tests include several exams that provide a comprehensive view of your lung health. Here’s a step-by-step guide to the most common tests:

  • Spirometry: This measures the amount of air you can inhale and exhale in a deep breath and how quickly you can do it. You’ll use a nose clip and breathe through a mouthpiece, starting with normal breaths, followed by a deep breath, and then exhaling quickly and completely.
  • Maximum Voluntary Ventilation (MVV): This test assesses the strength of your respiratory muscles. You’ll breathe deeply and rapidly for 12 seconds, and the test may be repeated to ensure your maximum effort is recorded.
  • Diffusion Capacity (DLCO): This estimates how efficiently your lungs transfer oxygen to your bloodstream. You’ll take a deep breath, hold the air in your lungs for a few seconds, and exhale slowly. A blood test may sometimes be required to measure oxygen levels.
  • Lung Volume Measurement (Plethysmography): This test measures your total lung capacity and the amount of air left in your lungs after exhaling completely. It’s done inside a small enclosed space, though you can open the door anytime if you feel uncomfortable.

How Long Does a Pulmonary Function Test Take?

The total time for pulmonary function tests can vary depending on how many tests are needed. Each test generally takes between 10 and 30 minutes. If you are doing all the tests, you might spend about an hour at the pulmonary function lab. Arriving on time and staying relaxed will help ensure accurate results.

Pulmonary Function Test Preparation: What to Do and Not to Do

To get the best results, follow these guidelines before your pulmonary function test (PFT):

What to Do:

  • Wear comfortable clothing that allows you to breathe freely.
  • If you use inhalers, ask your doctor if you should use them on the day of the test.
  • Arrive at least 15 minutes before your appointment to relax and prepare.

What Not to Do:

  • Avoid smoking for at least 4 to 6 hours before the test, as tobacco can affect the results.
  • Skip heavy meals and caffeinated drinks, which can interfere with your breathing.
  • Don’t engage in intense exercise at least 30 minutes before the test.

Equipment Used in Pulmonary Function Tests: What to Expect

During pulmonary function tests, several devices are used, with the primary one being a spirometer, which measures how much air you breathe in and out and how quickly. Sometimes, a plethysmograph, a small enclosed booth, is also used, where you’ll breathe normally and then with more intensity. The equipment is safe, and you can open the door if you feel uneasy.

Nose clips are often used to ensure no air escapes through your nose, as this could affect the results. The spirometer mouthpiece is disposable to maintain hygiene.

Pulmonary Function Test Cost: What You Should Know

The cost of pulmonary function tests can vary based on factors such as where the test is done, the number of tests needed, and whether you have insurance. In general, these tests can cost between $40 and $800. It’s a good idea to check with your insurance provider to see if the test is covered and what portion, if any, you’ll need to pay out of pocket.

Final Tips for Your Pulmonary Function Test

Though the equipment may seem intimidating at first, pulmonary function tests are non-invasive and generally comfortable. If you have claustrophobia, let the technician know so they can help you feel as comfortable as possible during the procedure.


Frequently Asked Questions

Can you eat before a pulmonary function test?
It’s best to avoid heavy meals before the test. Light meals are fine.

What equipment is used during a pulmonary function test?
A spirometer, plethysmograph, nose clips, and a disposable mouthpiece are typically used.

How do I prepare for a pulmonary function test?
Wear comfortable clothes, arrive early, and ask if you should avoid using inhalers.

What should I avoid before a pulmonary function test?
Avoid smoking, overeating, drinking caffeine, and intense exercise.

How much does a pulmonary function test cost?
The cost can range from $40 to $800, depending on the location and insurance.