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What are Pulmonary Function Tests?

Pulmonary function tests (also called lung function tests) are a group of noninvasive tests that help evaluate lung function. The tests measure various parameters such as lung capacity, volume, gas exchange, and rates of air flow.

When is Pulmonary Function Testing Indicated?

Pulmonary function testing is indicated to help diagnose or investigate potential health conditions such as:

  • Asthma
  • Chronic bronchitis
  • Allergies
  • Chronic obstructive pulmonary disease (COPD) such as emphysema
  • Respiratory infections
  • Lung fibrosis
  • Pulmonary tumors
  • Sarcoidosis
  • Scleroderma

Pulmonary function tests may also be indicated to monitor the effectiveness of treatment for chronic conditions such as COPD, bronchitis, or asthma.

It may be performed prior to surgery if you have a heart or lung problem or if you are a smoker.

It is also routinely performed for those working in coal mines or other environments which can compromise lung health.

Who Does Not Qualify for Pulmonary Function Testing?

Picture of Pulmonary Function Testing

Pulmonary function testing is contraindicated in individuals with:

  • Chest pain, unstable heart condition, or recent heart attack
  • Aneurysm (bulging blood vessel) in the belly, chest, or brain
  • Recent abdominal or chest surgery
  • Recent surgery to the eye as pressure may develop inside the eye during a PFT
  • Respiratory infection such as flu or cold or active tuberculosis

Common Types of Pulmonary Function Tests

Most pulmonary function tests are quick and simple. The processes and time involved vary depending on the type of test. Some of the common tests include:

  • Lung volume tests: This is a test that measures the amount of air your lungs can hold.
  • Pulse oximetry test: This test measures the level of oxygen in the blood, which indicates how well the lung is functioning.
  • Spirometry: This test measures the amount of air you breathe in and out, the rate of air flow, and your lung size.
  • Lung diffusion capacity: This test measures how well inhaled oxygen gets into the blood.
  • Exercise test: This test is used to measure how your lungs respond to exercise such as walking on a treadmill to investigate symptoms such as shortness of breath.

How Do You Prepare for Pulmonary Function Testing?

Your physician will explain the procedure to you and answer any questions you have. Tell your physician if you are taking any over-the-counter or prescription meds, vitamins, or herbal supplements. Before the test, you will need to:

  • Avoid consuming heavy food or drinks
  • Refrain from certain medications
  • Refrain from smoking and alcohol
  • Avoid strenuous activity
  • Refrain from wearing tight-fit clothing

How are Pulmonary Function Tests Performed?

You may have pulmonary function testing either as an outpatient procedure or as part of a longer hospital stay. The way the procedure is conducted depends on your health condition and the choice of method as directed by your physician. However, in most cases, the procedure is as follows:

  • You should empty your bladder before the procedure.
  • While sitting in a chair, a soft clip is placed on your nose to make sure that all breathing is done through the mouth.
  • Your mouth is placed over a sterile mouthpiece attached to a spirometer, forming a tight seal.
  • You will be instructed to breathe in and out in different ways.
  • You will be observed closely during the procedure for signs of trouble breathing, dizziness, or other issues.
  • After certain tests, you may be given a bronchodilator, and after the bronchodilator has taken effect, the tests are then repeated.

Alternatively, the tests may also be performed as you sit or stand inside an airtight enclosure resembling a telephone booth.

Risks of Pulmonary Function Tests

Pulmonary function testing is a noninvasive procedure; however, as with any procedure, it does have some risks including:

  • Shortness of breath
  • Asthma attack due to deep inhalation
  • Coughing
  • Dizziness while testing
  • Confusion

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