PFT Interpretation Chart

Access Carpatron's free PFT Interpretation Chart PDF download to better understand pulmonary function test results.

By Wynona Jugueta on Aug 2, 2025.

Fact Checked by Nate Lacson.

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What is a pulmonary function test (PFT)?

Pulmonary function tests (PFTs) are specialized lung function tests that measure how well the lungs perform critical functions such as air movement, gas exchange, and volume changes during respiration (Stanojevic et. al., 2022). This pulmonary function testing helps healthcare professionals assess the presence and severity of respiratory disease, including obstructive lung disease (e.g., chronic obstructive pulmonary disease) and restrictive lung disease. Commonly measured parameters include forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and total lung capacity (TLC), which provide valuable insights into respiratory mechanics.

PFTs are instrumental in identifying conditions such as upper airway obstruction or early signs of pulmonary impairment due to occupational exposures or pulmonary toxicity. While they do not offer a definitive diagnosis, they guide physicians in correlating total lung capacity results with the patient’s medical history, physical examination, and additional diagnostic data.

PFTs also aid in monitoring disease progression and treatment efficacy, quantifying changes in lung function over time. Proper technique and patient effort are crucial to obtaining reliable data, as poor effort can affect test accuracy. Updated spirometry guidelines from organizations such as the European Respiratory Society and American Thoracic Society ensure standardized measurements and interpretation for consistent clinical use (Graham et. al., 2019).

PFT Interpretation Chart Template

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What is a PFT Interpretation Chart?

A Pulmonary Function Test (PFT) Interpretation Chart is a structured tool used by healthcare professionals to analyze data from pulmonary function tests. It aids in evaluating lung function and identifying patterns associated with respiratory diseases such as obstructive lung disease, interstitial lung disease, or conditions affecting vital capacity and total lung capacity.

Key parameters such as forced expiratory volume (FEV1), forced vital capacity (FVC), and the FEV1/FVC ratio are central to interpreting whether the lung function test indicates an obstructive or restrictive pattern. The chart includes spirometry measurements are essential for interpreting pulmonary function. A FEV1/FVC ratio below 0.70 or the lower limit of normal (LLN) suggests an obstructive defect like asthma or COPD. An FVC below 80% of predicted indicates a restrictive defect, such as interstitial lung disease or chest wall disorders. Similarly, an FEV1 under 80% predicted may reflect either obstructive or restrictive lung disease. These metrics help clinicians identify and classify respiratory conditions effectively (Barreiro, 2004).

The PFT Interpretation Chart compares an observed lung function value to predicted reference ranges, adjusted for demographic factors, to estimate expected lung function. This approach ensures precision in assessing baseline lung function and tracking changes over time. The chart’s systematic method helps clinicians diagnose obstructive lung disease, like idiopathic pulmonary fibrosis, monitor disease progression, and evaluate the impact of treatments on lung volumes and capacity.

How does it work?

Carepatron’s PFT Interpretation Chart is designed to streamline the process of analyzing pulmonary function tests. Here’s how to use the chart step by step.

Step 1: Access the chart template

Click "Use template" in this page to open the template in the Carepatron app, where you can customize the resource, print it for physical use, or fill it out digitally. You can also click "Download" to save a fillable and printable ready-to-use PDF.

Step 2: Introduce the chart to the patient

During the pulmonary function test, ensure the patient is informed about the procedure and its purpose. Follow proper spirometry techniques to obtain reliable measurements like FEV1, FVC, and the FEV1/FVC ratio. Encourage maximum patient effort, as this is critical for accurate results. Record all necessary values directly into the PFT Interpretation Chart to maintain clear documentation and streamline interpretation.

Step 3: Discuss the components of the chart

Once test results are available, use the decision flowchart in the PFT Interpretation Chart to systematically interpret the findings. The flowchart corresponds with the Stepwise interpretation section, guiding you through identifying obstruction (Step 1), restriction (Step 2), severity (Step 3), and reversibility (Step 4). Follow each step carefully to classify the patient’s lung function and determine whether additional tests, such as DLCO or bronchoprovocation, are required.

Step 4: Provide further patient education and next steps

Offer additional education about the patient’s respiratory health based on chart findings. Discuss potential lifestyle modifications, treatment plans, or follow-up tests. Use the chart to emphasize the importance of monitoring lung function and staying proactive about managing their condition.

Benefits of using this chart

The PFT Interpretation Chart is an invaluable tool for medical professionals. It offers a systematic approach to interpreting pulmonary function testing results. By incorporating key metrics such as spirometry test results, flow volume loops, and forced expiratory flow, the chart ensures accurate identification of respiratory conditions like obstructive lung disease and restrictive patterns.

Using this chart enhances efficiency in clinical settings, including pulmonary function laboratories, by providing a clear framework to compare measured values, such as lung volumes and respiratory muscle pressures, with reference ranges like the lower limit of normal. It facilitates the detection of abnormalities in expiratory flow and other parameters, helping clinicians distinguish between normal lung function and pathological conditions.

The chart also improves communication within multidisciplinary teams by standardizing how results are presented and interpreted. It supports the evaluation of obstructive lung diseases, enabling professionals to track disease progression, assess treatment efficacy, and make informed decisions about patient care.

Overall, the PFT Interpretation Chart simplifies complex data, streamlines the diagnostic process, and ensures consistency in evaluating respiratory health. This makes it an essential resource for professionals working in respiratory care and related fields.

References

Barreiro, T. J., & Perillo, I. (2004). An approach to interpreting spirometry. American Family Physician, 69(5), 1107–1115. https://www.aafp.org/pubs/afp/issues/2004/0301/p1107.html

Graham, B. L., Steenbruggen, I., Miller, M. R., Barjaktarevic, I. Z., Cooper, B. G., Hall, G. L., Hallstrand, T. S., Kaminsky, D. A., McCarthy, K., McCormack, M. C., Oropez, C. E., Rosenfeld, M., Stanojevic, S., Swanney, M. P., & Thompson, B. R. (2019). Standardization of spirometry: 2019 update. An official American Thoracic Society and European Respiratory Society technical statement. American Journal of Respiratory and Critical Care Medicine (Am. J. Respir. Crit. Care Med), 200(8), e70–e88. https://doi.org/10.1164/rccm.201908-1590ST

Stanojevic, S., Kaminsky, D. A., Miller, M. R., Thompson, B., Aliverti, A., Barjaktarevic, I., Cooper, B. G., Culver, B., Derom, E., Hall, G. L., Hallstrand, T. S., Leuppi, J. D., MacIntyre, N., McCormack, M., Rosenfeld, M., & Swenson, E. R. (2022). ERS/ATS technical standard on interpretive strategies for routine lung function tests. European Respiratory Journal (Eur Respir J), 60(1), Article 2101499. https://doi.org/10.1183/13993003.01499-2021

Commonly asked questions

Interpret PFT results by analyzing key metrics such as FEV1, FVC, and the FEV1/FVC ratio, comparing them to predicted values and the lower limit of normal. These results help distinguish between obstructive lung disease, restrictive lung disease, or a mixed pattern.

The FEV1/FVC ratio is often the most important value as it differentiates between obstructive and restrictive lung patterns. A ratio below 0.70 typically suggests obstructive lung disease, while a normal ratio with reduced FVC may indicate restriction.

A "bad" result includes values significantly below predicted levels, such as an FEV1/FVC ratio under 0.70 or an FVC below 80% of predicted. These findings may indicate severe respiratory disease or impaired lung function requiring further investigation.