Taking a deep breath might seem simple, but for millions of people worldwide, understanding how well their lungs function can be the key to managing their health. Pulmonary function tests (PFTs) provide crucial insights into lung capacity and breathing efficiency, yet many patients find themselves puzzled when reviewing their results. Whether you’re a healthcare professional seeking reference examples or a patient trying to understand your own test results, this comprehensive guide breaks down real-world PFT results with clear explanations and practical examples.
Understanding the Basics of Pulmonary Function Test Measurements
Pulmonary function tests measure various aspects of lung function through specialized breathing maneuvers. The most common measurements include Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV1), and the FEV1/FVC ratio. These values are typically expressed as both absolute numbers and percentages of predicted normal values based on age, height, sex, and ethnicity.
According to the National Heart, Lung, and Blood Institute, normal lung function is generally defined as achieving 80% or more of the predicted values. Understanding these benchmarks helps interpret whether results indicate normal function, obstruction, restriction, or mixed patterns.
Normal Pulmonary Function Test Results Example
Let’s examine a typical normal PFT result for a 45-year-old male, 175 cm tall:
| Parameter | Measured Value | Predicted Value | % Predicted |
|---|---|---|---|
| FVC (L) | 4.85 | 4.78 | 101% |
| FEV1 (L) | 3.92 | 3.84 | 102% |
| FEV1/FVC Ratio | 81% | 80% | 101% |
| DLCO | 28.5 | 29.2 | 98% |
These results show all values within normal range (above 80% predicted), with an FEV1/FVC ratio above 70%, indicating healthy lung function without evidence of obstruction or restriction.
Obstructive Pattern Results Example
Obstructive lung diseases like COPD and asthma show characteristic patterns. Here’s an example from a 62-year-old female smoker with moderate COPD:
| Parameter | Pre-Bronchodilator | Post-Bronchodilator | % Change |
|---|---|---|---|
| FVC (L) | 2.45 (78%) | 2.58 (82%) | +5% |
| FEV1 (L) | 1.42 (58%) | 1.51 (62%) | +6% |
| FEV1/FVC Ratio | 58% | 59% | – |
Key findings indicate moderate obstruction with:
- Reduced FEV1 (58% predicted)
- Low FEV1/FVC ratio (<70%)
- Minimal bronchodilator response (<12% and <200ml improvement)
For healthcare professionals needing to calculate and interpret these values quickly, the PFT Calculator can help determine predicted values and severity classifications based on patient demographics.
Restrictive Pattern Results Example
Restrictive lung diseases affect lung expansion differently than obstructive diseases. Consider this example from a 55-year-old male with pulmonary fibrosis:
| Parameter | Measured Value | % Predicted | Interpretation |
|---|---|---|---|
| TLC (L) | 3.85 | 62% | Reduced |
| FVC (L) | 2.15 | 54% | Severely reduced |
| FEV1 (L) | 1.78 | 56% | Reduced |
| FEV1/FVC Ratio | 83% | Normal | Preserved |