The Importance of Pulmonary Function Tests Benefits, Types and What to Expect
Pulmonary function tests (PFTs) are essential, non-invasive tests that measure how well your lungs work by evaluating airflow, lung volume, and oxygen transfer.
With respiratory diseases such as chronic obstructive pulmonary disease (COPD) causing millions of deaths worldwide and conditions like asthma and pulmonary fibrosis becoming increasingly common, early lung assessment has never been more important.
Pulmonary function testing helps detect lung disorders early, monitor disease progression, evaluate treatment effectiveness, and assess lung health before surgery.
This blog explains the importance of the pulmonary function tests, different PFT types and how the procedures work.
What is the Importance of a Pulmonary Function Test?
If you are wondering what is the importance of pulmonary function tests, then you must note that these are essential non-invasive evaluations that measure lung capacity, airflow, and how efficiently oxygen moves from the lungs into the bloodstream.
Since the body depends on oxygen every second to function properly, even mild changes in lung performance can significantly affect overall health. These are the key importance everyone should know:
- Diagnostic Value: PFTs play a major role in diagnosing respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), emphysema, bronchitis and pulmonary fibrosis.
These tests identify airflow obstruction or restriction and help determine the underlying cause of symptoms like shortness of breath, wheezing, chest tightness, or persistent cough.
They also help distinguish between obstructive and restrictive lung diseases, allowing doctors to make more accurate diagnoses even when imaging tests such as chest X-rays or CT scans are inconclusive. - Monitoring and Treatment: Doctors use pulmonary function tests to monitor disease progression and evaluate how well treatments are working over time.
For chronic respiratory conditions like asthma and COPD, regular spirometry testing helps track changes in lung function. It also guides adjustments in medications or treatment plans.
PFTs are also useful in assessing lung damage caused by smoking, pollution, workplace chemicals, or other environmental exposures. - Pre-Surgery and Risk Assessment: Pulmonary function tests are commonly performed before surgery to assess whether a patient’s lungs can tolerate anaesthesia and recovery.
This helps reduce the risk of postoperative breathing complications, especially in individuals with existing lung or heart conditions.
Doctors also use PFTs to screen people exposed to occupational hazards. They also use them to evaluate conditions that indirectly affect lung function, such as neuromuscular disorders or connective tissue diseases like scleroderma.
What are the Types of Pulmonary Function Tests?
These are the types of pulmonary function tests you should know:
- Spirometry: Spirometry is one of the most widely used bedside pulmonary function tests for assessing airflow limitation.
It measures how much air you can inhale and exhale, as well as how quickly air moves out of the lungs. During the test, you breathe into a mouthpiece connected to a spirometer after taking a deep breath.
Key measurements include forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). Spirometry helps diagnose conditions such as asthma, COPD, and pulmonary fibrosis and is also useful for monitoring treatment response. - Lung Volume Testing (Plethysmography): Lung volume testing, also called body plethysmography, measures the total amount of air the lungs can hold and the air remaining after exhalation. Healthcare professionals perform the test inside a sealed transparent chamber while you breathe through a mouthpiece.
It helps distinguish restrictive lung diseases from obstructive conditions and measures airway resistance accurately. - Diffusion Capacity Test (DLCO): The diffusion capacity test evaluates how effectively oxygen moves from the lungs into the bloodstream. During the procedure, you inhale a harmless gas mixture, hold your breath briefly, and exhale into a machine. Lower DLCO values may indicate emphysema, pulmonary fibrosis, or pulmonary vascular disorders.
- Cardiopulmonary Exercise Test (CPET): CPET measures how the heart, lungs, and muscles function together during physical activity. Doctors usually perform the test on a treadmill or stationary bicycle while monitoring oxygen use, breathing patterns, heart rate, and carbon dioxide production. It helps identify causes of exercise intolerance and unexplained breathlessness.
- Bronchial Provocation Test: This test evaluates airway sensitivity and is commonly used to diagnose asthma. Patients inhale substances such as methacholine to trigger airway narrowing, followed by spirometry testing. A significant drop in lung function indicates airway hyperresponsiveness.
- Exhaled Nitric Oxide Test (FeNO): The FeNO test measures nitric oxide levels in exhaled breath to detect airway inflammation, particularly allergic asthma. The patient exhales slowly into a handheld device, and elevated nitric oxide levels may indicate eosinophilic airway inflammation.
What to Expect During a Pulmonary Function Test?
A pulmonary function test (PFT) follows a structured process to measure how well your lungs work. Before the test, you may be asked to avoid smoking, caffeine, heavy meals, strenuous exercise, or certain breathing medications.
Comfortable clothing is also recommended to allow easy breathing. During the test, a technician records details such as your age, height, weight, and sex to compare your results with standard lung values.
The procedure usually involves breathing into a mouthpiece connected to devices such as a spirometer or plethysmograph. Depending on the test type, you may perform deep inhalations, forceful exhalations, breath-holding, or exercise on a treadmill or stationary bicycle. Some tests use nose clips to ensure accurate airflow measurements.
The process is painless, generally takes 15 to 45 minutes, and may be repeated several times for accuracy. Most people can return to normal activities immediately after testing.
Final Word
Pulmonary function tests (PFTs) are important tools for assessing lung health and identifying respiratory conditions such as asthma, COPD and pulmonary fibrosis.
Different tests, including spirometry, plethysmography, DLCO, CPET, and FeNO testing, provide detailed insights into how well the lungs function.
The procedure is generally safe, painless and completed within a short time, although pulmonary function tests cost may vary depending on the type of test and healthcare facility.
Early pulmonary function testing can help detect breathing problems sooner, support accurate treatment decisions, and improve long-term respiratory health and overall quality of life.
Reader Information: This article is intended for informational and educational purposes only and should not be considered medical advice. Pulmonary function test results should always be interpreted by a qualified healthcare professional in the context of your symptoms, medical history, and overall health condition. If you have concerns about your lung health, consult your doctor for personalised evaluation and guidance.
FAQ's
1.Can PFT detect heart problems?
Spirometry and pulmonary function testing are valuable tools not only for evaluating lung health but also for helping cardiologists assess cardiovascular risk, including conditions such as coronary artery disease, supporting earlier detection and more proactive patient management.
2. What should I avoid before a PFT?
Before a pulmonary function test, avoid smoking, caffeine, heavy meals, vigorous exercise, and tight clothing. Your doctor may also advise temporarily stopping bronchodilator inhalers to ensure accurate lung function measurements and reliable pulmonary test results.
3. What are the risks of a PFT test?
Some pulmonary function tests may cause temporary shortness of breath, chest discomfort, dizziness, or headache. However, trained healthcare professionals closely monitor you throughout the procedure and can stop the test immediately if you feel uncomfortable at any point.
4. At what age does lung function start to decline?
Lungs usually reach full maturity between the ages of 20 and 25. After age 35, lung function naturally begins to decline gradually, which can make breathing less efficient and slightly more difficult as part of the normal ageing process.
5. Should I take my inhaler before a PFT?
Before your pulmonary function test (PFT), you may take all regular medications unless instructed otherwise. Do not use inhalers or nebuliser treatments for at least 4 hours before the test, as they may affect the accuracy of your breathing results.
