Pulmonary Function Tests (PFTs): Types, Procedure, Benefits & Risks

A pulmonary function tests (PFTs) determines how well your lungs are working. It can determine how much air goes in and out of your lungs, how much air goes from your lungs to your blood, and how well your lungs work during exercise.

What are Pulmonary Function Tests?

Pulmonary function tests are various tests that measure how well your lungs exchange air. You will know that our lungs help take in air (inhale) and breathe air out (exhale) to survive.

There are many different types of PFTs and they are extremely safe and non-invasive (no tools or instruments are inserted into your body). PFTs are also called lung function tests.

A pulmonary function test is very simple. A PFT consists of a clear, air-tight box, soft nose clips, a mouthpiece, and a small electronic machine that measures your airflow (spirometer).

The way the test is done may vary. The process followed is:

• You will be asked to wear loose clothing and remove any jewellery that may be restrictive for the test.
• Those wearing dentures will have to wear them during the test.
• You should empty your bladder before the test.
• You will sit on a chair. A soft clip will be placed on your nose. All you breathing from now on will be done through your mouth, not your nose.
• A disposable mouthpiece will be given to you that is attached to a spirometer.
• You will form a tight seal over the mouthpiece with your mouth. You will be instructed to inhale and exhale in different ways.
• The healthcare provider will watch you carefully to see if you have dizziness, breathing trouble or any other problems.
• After some tests, you will be given a bronchodilator. It is a medicine that causes the widening of the bronchi, which are the large air tubes that lead from the trachea (windpipe) to the lungs.
• The tests will be repeated after the bronchodilator has taken effect.

PFTs are done for a variety of reasons. Healthy people can be given PFTs as part of routine physical check-ups. They are also done in certain work environments, like graphite factories or coal mines, to ensure employee health. They could also be used to diagnose a health problem.

Risks Associated with Pulmonary Function Testing

Pulmonary function testing is generally considered safe. However, some people may experience temporary symptoms like dizziness, lightheadedness, fatigue from deep breathing, or coughing due to blowing forcefully into the mouthpiece. If needed, you can request a break during the test.

In very rare instances, the test may lead to a collapsed lung (pneumothorax). Additionally, PFTs can cause an increased heart rate. Be sure to inform your healthcare provider if you’ve recently had a heart attack or have any existing heart conditions.

Types of Pulmonary Function Tests

Pulmonary function tests (PFTs) are used to evaluate how effectively your lungs are functioning by checking lung volume, airflow, capacity, and gas exchange. Here are some of the most commonly performed PFTs:

1. Spirometry

Spirometry measures the amount of air flowing in and out of the lungs. It also gives a rough estimate of the size of the patient’s lungs. To do this test, a soft clip will be placed on your nose, and you will breathe in and out through your mouth. A mouthpiece will be placed in your mouth, and it is connected to a spirometer. Your healthcare provider will give you instructions on breathing in and out. Spirometry can tell whether a patient has a breathing problem caused by an obstruction of air entering the lungs.

2. Lung Volume Testing

The volume of air in the lungs at different phases of the breathing cycle is measured. Lung volume testing, also called plethysmography, is like spirometry, but is done in a small, air-tight booth with clear walls. It is performed using a machine called the plethysmograph. You are seated during the test. You are asked to breathe in and out and, at times, to pant. This test is useful to distinguish whether you have a restrictive lung disease (pulmonary fibrosis) or an obstructive lung disease like asthma.

3. Gas Exchange Testing

Here, the extent to which oxygen passes from the air sacs of the lungs to the blood is measured. You will be asked to breathe normally, take deep breaths, and hold your breath briefly. Several lung diseases can be assessed with this test.

4. Maximal Voluntary Ventilation (MVV)

Through this test, one can measure the amount of air that can be inhaled and exhaled in one minute. You will be asked to breathe in and out as forcefully as possible. The test can assess the overall functioning of the respiratory system. If you have asthma, upper airway obstruction, stiffness of the respiratory system, and respiratory muscle weakness, your MVV will be reduced.

5. Oxygen Titration Test

This test is used to determine the need for oxygen and to check if patients who are already receiving oxygen are receiving the right amount. The saturation of the oxygen is measured using a device called the oximeter, and the heart rate is also recorded. The flow of oxygen is adjusted to maintain acceptable levels of oxygen in the bloodstream.

6. Cardiopulmonary Exercise Testing

This is to assess your capacity to exercise. You will be asked to ride a stationary bike. Your heart and lungs will be monitored at rest, during warm-up, during a short exercise period, and during recovery when you are no longer pedalling. The test can evaluate causes of shortness of breath and or decreased exercise tolerance. Instead of a bike, a treadmill can also be used.

There are several more types of pulmonary tests that can be administered. We have seen only a few basic types.

Preparing for a Pulmonary Function Test

Before taking a pulmonary function test, your healthcare provider will advise you to:

• Stop taking your breathing medicines for a short period
• Wear loose, comfortable clothing that does not restrict your chest area
• Do not do any heavy exercise before your test
• Avoid tobacco products before your test
• You must not eat a heavy meal before your PFT
• You must avoid taking any caffeine before your PFT

Interpreting PFT Results

Results of the pulmonary function test will be available within a few days. PFT results can indicate several things:

• Lung disease: Abnormal PFT results can indicate a chest or lung disease. Certain lung diseases like asthma, chronic bronchitis, can cause the lungs to contain too much air and therefore the lungs take longer to empty. Certain lung diseases can make the lungs smaller, causing them to contain very little air.
• Before surgery, A PFT can be performed to check lung function.
• Lung damage: PFTs can assess lung damage due to exposure to chemicals or other substances.
• Treatment response: A PFT can be used to determine how well your lungs are responding to treatments.

Conditions Diagnosed with PFTs

Pulmonary function tests can help diagnose and monitor a range of lung conditions. These could include:

• Asthma
• Bronchitis
• Chronic obstructive pulmonary disease
• Emphysema
• Pulmonary fibrosis
• Pulmonary hypertension
• Allergies
• Damaged or scarred lung tissue
• Lung cancer
• Infections
• Thickening, or hardening of your connective tissues (scleroderma)
• Weakness of the muscles in the wall of the chest
• Stretched and enlarged airways
• Sarcoidosis, a collection of inflammatory cells around organs

Conclusion

Pulmonary function tests are important when you have been diagnosed with a breathing problem or when doctors think that you may be having one. A PFT helps your healthcare provider diagnose any conditions that affect your lungs. PFTs do long take a long time and are not painful. PFTs are often used to rule out any lung condition.

Frequently Asked Questions