Tiffeneau Index Calculator | HealthCalculum

Calculate the Tiffeneau Index (FEV1/FVC ratio) to assess pulmonary function. Free evidence-based tool.

Important Medical Disclaimer

This calculator is an educational and clinical decision support tool. Results DO NOT replace professional medical evaluation, laboratory tests, or clinical judgment. Always consult a qualified healthcare professional for diagnosis, treatment, and clinical decisions. Calculations are based on scientifically validated formulas but may not be applicable to all patients.

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What is the Tiffeneau Index?

The Tiffeneau Index, also known as the FEV1/FVC ratio, is a fundamental spirometric parameter for assessing lung function. It represents the percentage of air volume that can be exhaled in the first second (FEV1) relative to the total forced exhaled volume (FVC). This index is essential for differentiating obstructive from restrictive lung diseases.

Tiffeneau Index = (FEV1 / FVC) × 100

How to Calculate the Tiffeneau Index?

The calculation is simple: divide FEV1 by FVC and multiply by 100 to get the percentage. Normal values are generally ≥70% (≥0.70). Values below 70% suggest an obstructive pattern, characteristic of COPD, asthma, and other obstructive airway diseases.

Limitations and Considerations

The Tiffeneau Index should be interpreted along with other spirometric parameters and the patient's clinical picture. Exam quality depends on patient cooperation and proper technique. Borderline values (65-75%) may require additional assessment. Always consult a pulmonologist for complete interpretation of results.

Frequently Asked Questions

What does a Tiffeneau Index below 70% mean?

An index below 70% indicates an obstructive pattern, suggesting diseases like COPD, asthma, or other conditions causing airflow obstruction.

What is the normal Tiffeneau Index value?

The normal value is generally ≥70% (≥0.70). Values above this threshold indicate no significant airflow obstruction.

What are FEV1 and FVC?

FEV1 (Forced Expiratory Volume in 1 second) is the volume of air exhaled in the first second of a forced expiration. FVC (Forced Vital Capacity) is the total volume of air exhaled during the entire forced expiratory maneuver.

How is spirometry performed?

The patient breathes normally, then takes a deep breath and blows as hard and fast as possible into a spirometer. The maneuver is repeated several times to ensure reliable results.

Scientific References

1. Miller MR, Hankinson J, Brusasco V, et al. Standardisation of spirometry. Eur Respir J. 2005;26(2):319-338.
2. Pellegrino R, Viegi G, Brusasco V, et al. Interpretative strategies for lung function tests. Eur Respir J. 2005;26(5):948-968.
3. Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global Strategy for the Diagnosis, Management, and Prevention of COPD. 2023.
4. Quanjer PH, Stanojevic S, Cole TJ, et al. Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations. Eur Respir J. 2012;40(6):1324-1343.
5. American Thoracic Society. Lung function testing: selection of reference values and interpretative strategies. Am Rev Respir Dis. 1991;144(5):1202-1218.
6. Crapo RO, Casaburi R, Coates AL, et al. Guidelines for methacholine and exercise challenge testing-1999. Am J Respir Crit Care Med. 2000;161(1):309-329.