Introduction
Breathing is something we often take for granted—until it becomes difficult. Pulmonary Function Testing (PFT) is a crucial diagnostic tool that helps healthcare providers assess lung function, detect respiratory disorders, and monitor treatment effectiveness.
In this comprehensive guide, we’ll explore:
- What Pulmonary Function Testing is and why it’s important
- Different types of PFTs and how they work
- Who should get tested and what to expect
- How to interpret results
- The role of PFT in managing lung diseases
By the end, you’ll have a clear understanding of how these tests help diagnose conditions like asthma, COPD, and fibrosis—and why they’re essential for maintaining optimal respiratory health.
What is Pulmonary Function Testing (PFT)?
Pulmonary Function Testing is a non-invasive procedure that measures how well your lungs work. It evaluates:
- Lung capacity – How much air your lungs can hold
- Airflow rates – How quickly you can inhale and exhale
- Gas exchange efficiency – How well oxygen enters your blood
These tests help diagnose respiratory conditions, assess disease progression, and determine the effectiveness of treatments like inhalers or bronchodilators.
Types of Pulmonary Function Tests
1. Spirometry
Purpose: Measures airflow and lung volume.
How it works: You’ll take a deep breath and exhale forcefully into a spirometer.
Key metrics:
- Forced Vital Capacity (FVC) – Total air exhaled
- Forced Expiratory Volume (FEV1) – Air exhaled in the first second
- FEV1/FVC Ratio – Helps differentiate between obstructive (e.g., asthma) and restrictive (e.g., pulmonary fibrosis) lung diseases.
Common uses: Diagnosing asthma, COPD, and evaluating pre-surgical lung function.
2. Lung Volume Measurement
Purpose: Assesses total lung capacity (TLC).
Methods:
- Body Plethysmography – You sit in a sealed booth and breathe into a mouthpiece.
- Nitrogen Washout or Helium Dilution – Measures lung volume by tracking gas concentrations.
Why it’s important: Helps identify restrictive lung diseases where lung expansion is limited.
3. Diffusing Capacity Test (DLCO)
Purpose: Evaluates how well oxygen passes from the lungs into the bloodstream.
How it works: You inhale a small amount of carbon monoxide (CO), hold your breath for 10 seconds, and then exhale. The test measures how much CO is absorbed.
Key conditions detected: Emphysema, pulmonary fibrosis, and pulmonary hypertension.
4. Bronchial Provocation Test
Purpose: Checks for asthma by measuring airway responsiveness.
How it works: You inhale a substance (like methacholine) that may trigger mild bronchoconstriction in asthmatics. Spirometry is then repeated.
Who needs it? People with suspected asthma but normal spirometry results.
5. Exercise Stress Test
Purpose: Evaluates lung function during physical activity.
How it works: You’ll walk on a treadmill or ride a stationary bike while your oxygen levels, heart rate, and breathing are monitored.
Used for: Diagnosing exercise-induced asthma or unexplained shortness of breath.
Who Needs Pulmonary Function Testing?
PFTs are recommended for individuals with:
✔ Chronic cough or wheezing
✔ Shortness of breath (dyspnea)
✔ Known lung diseases (COPD, asthma, cystic fibrosis)
✔ Occupational exposure to lung irritants (e.g., coal dust, asbestos)
✔ Pre-surgical assessment (especially before major surgeries)
According to the American Thoracic Society (ATS), over 16 million Americans have COPD, and many remain undiagnosed—making PFTs critical for early detection.
What to Expect During a PFT
Before the Test
- Avoid smoking, heavy meals, or bronchodilators 4-6 hours before testing.
- Wear loose clothing for unrestricted breathing.
During the Test
- A technician will guide you through breathing maneuvers.
- You may be asked to blow into a tube repeatedly.
- Some tests take 30-45 minutes.
After the Test
- You can resume normal activities immediately.
- Results are typically reviewed by a pulmonologist.
Interpreting PFT Results
| Parameter | Normal Value | Obstructive Pattern (e.g., COPD, Asthma) | Restrictive Pattern (e.g., Pulmonary Fibrosis) |
|---|---|---|---|
| FEV1 | ≥80% predicted | Decreased | Normal or decreased |
| FVC | ≥80% predicted | Normal or decreased | Decreased |
| FEV1/FVC Ratio | ≥0.7 | <0.7 | Normal or increased |
| DLCO | ≥75% predicted | Decreased (in emphysema) | Decreased (in fibrosis) |
Example:
- Low FEV1/FVC (<0.7) suggests obstructive disease (COPD/asthma).
- Low FVC with normal FEV1/FVC indicates restrictive disease.
Why PFTs Matter in Lung Disease Management
- Early Detection: Identifies lung impairment before symptoms worsen.
- Treatment Monitoring: Helps adjust medications (e.g., inhalers for asthma).
- Occupational Safety: Ensures workers in high-risk environments (mining, construction) have healthy lung function.
A 2020 study in Chest Journal found that early PFT screening reduced COPD-related hospitalizations by 22%.
Frequently Asked Questions (FAQs)
1. Is Pulmonary Function Testing painful?
No, PFTs are non-invasive and painless. Some people may feel lightheaded after vigorous breathing.
2. How often should PFTs be done?
- Asthma/COPD patients: Every 1-2 years.
- High-risk workers: Annually.
3. Can PFTs diagnose lung cancer?
No, but they help assess lung health before biopsies or surgeries.
Conclusion
Pulmonary Function Testing is a vital tool for diagnosing and managing respiratory conditions. Whether you’re experiencing breathing difficulties or monitoring an existing condition, PFTs provide invaluable insights into lung health.
Need a PFT? Consult a pulmonologist today to ensure your lungs are functioning at their best!
