Pulmonary Function Testing (PFT) – Purpose, Procedure, and Results

Introduction

Pulmonary Function Testing (PFT) is a crucial diagnostic tool used to assess how well your lungs are working. These non-invasive tests measure lung capacity, airflow, and gas exchange, helping doctors diagnose conditions like asthma, COPD, and pulmonary fibrosis.

What is Pulmonary Function Testing (PFT)?

Pulmonary Function Testing refers to a group of tests that evaluate how effectively your lungs take in and release air, as well as how well they transfer oxygen into your blood. These tests help pulmonologists diagnose and monitor lung diseases, assess treatment effectiveness, and determine surgical risks.

Key Measurements in PFTs:

• Lung volumes – How much air your lungs can hold

• Airflow rates – How quickly you can inhale and exhale

• Gas exchange efficiency – How well oxygen passes into your bloodstream

Types of Pulmonary Function Tests

There are several types of PFTs, each serving a specific purpose:

1. Spirometry

The most common PFT, spirometry measures how much and how quickly you can exhale air. It helps diagnose:

• Asthma

• Chronic Obstructive Pulmonary Disease (COPD)

• Restrictive lung diseases (e.g., pulmonary fibrosis)

How it works: You’ll take a deep breath and blow forcefully into a spirometer. The machine records:

• Forced Vital Capacity (FVC) – Total air exhaled

• Forced Expiratory Volume in 1 second (FEV1) – Air exhaled in the first second

A low FEV1/FVC ratio suggests obstructive lung disease (e.g., COPD), while a low FVC indicates restrictive disease.

2. Lung Volume Measurement

This test determines the total amount of air your lungs can hold. Methods include:

• Body Plethysmography – You sit in a sealed booth and breathe into a mouthpiece.

• Helium Dilution or Nitrogen Washout – Measures lung volume using gas concentrations.

3. Diffusion Capacity Test (DLCO)

This evaluates how well oxygen passes from your lungs into your bloodstream. A reduced DLCO may indicate:

• Emphysema

• Pulmonary fibrosis

• Pulmonary hypertension

4. Bronchial Provocation Test

Used to diagnose asthma, this test involves inhaling substances (like methacholine) that trigger airway narrowing in asthmatics.

5. Exercise Stress Test

Assesses lung function during physical activity, helping diagnose exercise-induced asthma or other exertion-related breathing problems.

Who Needs Pulmonary Function Testing?

PFTs are recommended for individuals with:

• Chronic cough or wheezing

• Shortness of breath (dyspnea)

• Suspected asthma or COPD

• Pre-surgical evaluation (especially before lung surgery)

• Monitoring lung disease progression

• Occupational exposure risks (e.g., miners, construction workers)

According to the American Thoracic Society (ATS), early PFT screening can help detect lung diseases before symptoms worsen.

How to Prepare for a Pulmonary Function Test

To ensure accurate results:
✅ Avoid smoking for at least 24 hours before the test.
✅ Skip heavy meals and caffeine 4-6 hours beforehand.
✅ Wear loose clothing to allow unrestricted breathing.
✅ Inform your doctor about recent illnesses or medications.

What to Expect During the Test

1. Spirometry: You’ll take deep breaths and exhale forcefully into a tube.

2. Lung Volume Test: You’ll sit in a clear booth while breathing normally.

3. Diffusion Test: You’ll inhale a harmless gas and hold your breath briefly.

The entire process takes 30-90 minutes, depending on the tests performed.

Understanding PFT Results

Your doctor will compare your results to normal values based on age, sex, height, and ethnicity. Abnormal results may indicate:

Why Are PFTs Important?

1. Early Diagnosis – Detects lung diseases before severe symptoms appear.

2. Disease Monitoring – Tracks progression and treatment effectiveness.

3. Surgical Risk Assessment – Determines if lungs can handle anesthesia.

4. Occupational Health – Screens workers exposed to lung hazards.

A 2023 study in Chest Journal found that PFTs reduce hospitalizations by 22% in COPD patients through early intervention.

Frequently Asked Questions (FAQs)

1. Are PFTs painful?

No, PFTs are non-invasive and painless, though some may feel slightly breathless during forced exhalation.

2. Can I take my medications before a PFT?

Consult your doctor. Some medications (like bronchodilators) may need to be paused.

3. How often should PFTs be done?

Depends on your condition. COPD patients may need annual tests, while pre-surgical patients require one-time testing.

4. What’s the cost of a PFT?

Prices range from $200-$800, depending on insurance and test complexity.

Conclusion

Pulmonary Function Testing is a vital tool for diagnosing and managing respiratory conditions. Whether you’re experiencing breathing difficulties or need pre-surgical clearance, PFTs provide critical insights into lung health.

If you suspect a lung issue, consult a pulmonologist and discuss whether PFTs are right for you. Early detection can significantly improve treatment outcomes.

Have you undergone a PFT? Share your experience in the comments!