When are Pulmonary Function Tests (PFT) Needed?


PFTs, or pulmonary function tests, are tests that determine how effectively the lungs perform. The client can breathe normally and silently during part of the test measurements. Other tests necessitate a forced intake or exhalation following a deep breath. They may be instructed to breathe a different gas or drug to see how it affects their test findings.

There are many types of lung function tests, which are prescribed according to the requirement,

  • Spirometry
  • Spirometry sitting/supine
  • Body plethysmography
  • Methacholine inhalation challenge
  • Six-minute walk test
  • Exhaled nitric oxide test
  • Arterial blood gas test
  • Lung volume test
  • Lung diffusion capacity
  • Cardiopulmonary exercise test
  • Oximetry with ambulation
  • Respiratory muscle strength test
  • Altitude simulation tests
  • Exercise challenge (spirometry before and after)
  • Shunt study (100% O₂)
  • Maximal voluntary volume (MVV)


One of the most common lung function tests that are performed is spirometry. You violently exhale and then inhale into a tube connected to a machine called a spirometer during this exam. The spirometer records the amount of air you exhaled and then inhaled back into your lungs. To gain an accurate evaluation of your lung function, you will be asked to repeat this test two or three times. This test will take you about 30 minutes to complete. Pulmonary function test hospital can help in providing the right tests that aid in diagnosing the condition.

Diffusion testing:

Diffusion tests determine how well oxygen from your lungs reaches your bloodstream. This test, like spirometry, requires you to breathe into a mouthpiece linked to a machine. You’ll be urged to slowly exhale as much air as you can to empty your lungs. Then you’ll take a rapid yet deep breath in, hold it for 10 seconds, and then breathe out. This procedure takes almost about 15 minutes to complete. 

Body plethysmography:

Body plethysmography is a test that measures how much air is in your lungs after you take a deep inhale and how much air is remaining when you exhale. Your healthcare professional can tell how well your lungs are operating by measuring the total amount of air your lungs can hold and the amount of air left in your lungs when you breathe out. Consult your doctor to understand the best pulmonary function test for asthma and undergo the diagnosis to get the right treatment.

It would be best if you sat in an enclosed plastic box that you could see through for this test. You will be required to wear a nasal clip and will be taught how to breathe via a mouthpiece. It takes roughly 15 minutes to complete the test.

What can pulmonary function tests be used for?

  • Compare your lung function to established benchmarks to see how well your lungs should be performing.
  • Measure the impact of chronic disorders on lung function, such as asthma, chronic obstructive pulmonary disease (COPD), or cystic fibrosis.
  • Detect early changes in lung function that may indicate the need for a treatment change.
  • Identify any constriction of the airways.
  • Determine whether a drug (such as a bronchodilator) could be beneficial.
  • Demonstrate whether your lungs were affected as a result of exposure to toxins in your home or job.
  • Determine your tolerance for surgery and other medical procedures.

Why are pulmonary function tests prescribed?

Lung tests can aid doctors in the diagnosis of lung illnesses such as:

  • Asthma
  • Allergies
  • Chronic bronchitis
  • Chronic obstructive pulmonary disease (COPD)
  • Damaged or scarred lung tissue
  • Disease caused by breathing in asbestos fibers
  • Sarcoidosis is a collection of inflammatory cells around organs
  • Lung cancer
  • Infections
  • Thickened, stretched, or enlarged airways
  • Thickening or hardening of your tissues (scleroderma)
  • Weakness of the wall muscles of the chest

PFTs at a PFT hospital can be used to monitor lung function in patients with lung or heart difficulties, smokers, or other health issues before surgery or other operations. PFTs are also used to assess asthma, emphysema, and other chronic lung disorders treatment. Your healthcare professional may recommend PFTs for different reasons.

How to get accurate results from pulmonary function tests?

  • For at least 1 hour before the test, do not smoke.
  • Do not consume alcohol for at least 4 hours before the examination.
  • For at least 30 minutes before the test, avoid strenuous exercise.
  • Do not wear apparel that restricts your ability to take a deep breath.
  • Avoid eating a substantial meal within two hours of the test.
  • Inquire with your doctor whether there are any medications you should avoid taking on the day of your test. Reach out to the lungs specialist hospital in Coimbatore to understand the options that are available to diagnose the condition.

What do pulmonary function tests measure?

The pulmonary function tests are highly beneficial to measure,

  • Tidal volume (VT)
  • Minute volume (MV)
  • Vital capacity (VC)
  • Functional residual capacity (FRC)
  • Residual volume
  • Total lung capacity
  • Forced vital capacity (FVC)
  • Forced expiratory volume (FEV)
  • Forced expiratory flow (FEF)
  • Peak expiratory flow rate (PEFR)

How do you prepare for pulmonary function tests?

Your doctor will go over the test with you and tell you what to expect. Any queries you may have can be directed to the specialist. They may also advise you to dress comfortably in loose clothing.

For the best results, follow these steps:

  • Unless your doctor advises you otherwise, take your meds before your test.
  • Before the test, don’t smoke; ask your doctor how long you should wait before quitting.
  • Avoid intake of alcohol for at least 4 hours prior to the test.
  • At least 2 hours before the test, avoid eating a substantial meal.
  • Do not engage in any strenuous exercise for at least 30 minutes before the test.

How much time does it take to get pulmonary function test results in Coimbatore?

The majority of tests last 15 to 30 minutes. You can feel exhausted afterward. You will be given time to rest by your medical staff. After that, you can normally resume your regular activities. Your age, height, race, and sex determine your customary values. The percentages represent the normal findings. If a value is less than 80% of your projected value, it is termed abnormal.

Taller men and women, for example, have larger lungs, whereas shorter women and men have smaller lungs. As you become older, it’s natural for your lung function to decline gradually. Reach out to the Best Multispeciality Hospital in Coimbatore, to undergo pulmonary function tests.

Your healthcare professional will utilize these guidelines based on your height, age, and sex at birth. These figures are referred to as “predicted values.” These anticipated values will be compared to your measured values.

Normal value ranges may differ slightly between laboratories due to slightly varied methods for calculating normal values. Discuss the importance of your specific test results with your healthcare professional.