If your doctor has recommended a pulmonary function test (PFT), you may be wondering what it involves, how to prepare, and what your results can tell you. At Rockford Pulmonary Clinic, our team performs these tests daily to help evaluate how well your lungs are working and guide your treatment plan with precision and care.
Below, we’ll walk through what to expect before, during, and after your pulmonary function test.
What Is a Pulmonary Function Test?
A pulmonary function test is a group of breathing tests that measure how efficiently your lungs move air in and out and how well they deliver oxygen to your bloodstream.
These tests help diagnose and monitor conditions such as:
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Asthma
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Chronic Obstructive Pulmonary Disease (COPD)
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Pulmonary fibrosis
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Sarcoidosis
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Restrictive or obstructive lung disease
The results provide valuable insights into your lung capacity, airflow, and overall respiratory health.
Preparing for Your Test
To ensure accurate results, it’s important to follow these simple preparation steps before your appointment:
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Avoid smoking for at least 4–6 hours before the test.
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Do not use your inhaler or bronchodilator unless your doctor instructs you to do so.
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Wear loose, comfortable clothing that allows you to take deep breaths easily.
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Eat lightly and avoid a heavy meal right before testing.
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Bring a list of medications you currently take.
Your healthcare provider may give you additional or specific instructions depending on your condition.
What Happens During the Test
At Rockford Pulmonary Clinic, your comfort and understanding come first. Here’s what you can expect during each phase of the test:
1. Introduction and Instructions
A respiratory therapist or technician will explain each part of the test. You’ll sit in a chair or inside a clear booth and use a mouthpiece connected to specialized equipment.
2. Breathing Exercises
You’ll be asked to take deep breaths, exhale quickly, or breathe normally at various times. The technician may guide you to repeat some steps to ensure consistent results.
3. Spirometry
This is the most common component. It measures how much air you can inhale and exhale, and how fast. You’ll blow into the mouthpiece as forcefully as you can after taking a deep breath.
4. Lung Volume Measurement
In some cases, the test includes measuring the total amount of air your lungs can hold. This may involve sitting in a sealed booth where gentle pressure changes help calculate lung capacity.
5. Diffusion Capacity
This part checks how well your lungs transfer oxygen from the air to your blood. You’ll briefly inhale a harmless gas mixture and exhale it into the machine for analysis.
The entire procedure typically takes 30 to 60 minutes and is noninvasive, safe, and painless.
After the Test
You can return to your normal activities immediately. Your doctor will review the results and discuss them with you, explaining what they mean for your lung health and treatment plan.
Common outcomes include identifying:
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Reduced airflow (as seen in asthma or COPD)
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Decreased lung volume (as seen in restrictive diseases)
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Changes in oxygen exchange efficiency
Your pulmonologist may use this data to adjust medications, recommend additional testing, or track improvements over time.
Why Pulmonary Function Testing Matters
Regular lung function testing provides early insight into changes in your respiratory health—often before you feel noticeable symptoms. It allows your care team to:
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Monitor the effectiveness of your treatment plan
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Detect lung function decline early
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Personalize your care for optimal outcomes
At Rockford Pulmonary Clinic, we combine advanced diagnostic tools with compassionate care to help every patient breathe easier.
Schedule Your Pulmonary Function Test
If you’ve been referred for a pulmonary function test or are experiencing symptoms such as shortness of breath, chronic cough, or wheezing, our team is here to help.
Contact Rockford Pulmonary Clinic today to schedule your appointment and take the next step toward understanding and improving your lung health.
