93 Test Tiffeneau

Tiffeneau index (FEV1/FVC): airflow obstruction, lower limit of normal versus the GOLD 0.70 ratio.

The Tiffeneau index (Tiffeneau–Pinelli index) is the ratio of the forced expiratory volume in the first second (FEV1) to the vital capacity (VC or FVC). It shows what proportion of the vital capacity a person can blow out in one second. Healthy lungs empty quickly, so the ratio is high, usually above about 0.70–0.80 in adults (it falls slowly with age). A reduced ratio is the defining feature of airflow obstruction, as in asthma and COPD. A normal or high ratio with a reduced vital capacity suggests restriction.

SpirometryCOPDAsthma

FormulaFEV1 / FVC (or VC)

Obstruction (ERS/ATS)below lower limit of normal

COPD (GOLD)post-bronchodilator < 0.70

Changes withage (decreases)

Figure 1. Schematic volume–time curves. The volume at 1 second is FEV1; the plateau is FVC. In obstruction air leaves slowly; in restriction the total volume is small.

Interpretation

The ERS/ATS standard defines obstruction as FEV1/FVC below the lower limit of normal (5th percentile) for age, sex and height. The GOLD report for COPD uses a fixed post-bronchodilator ratio below 0.70, which is simple but overdiagnoses obstruction in older people and underdiagnoses it in the young. Severity is graded by FEV1. Reversibility after a bronchodilator supports asthma. In this application the index is estimated from circulatory parameters; spirometry remains the reference method for measuring it.

Causes of a low ratio

COPD (chronic bronchitis, emphysema), mainly due to smoking
Asthma, bronchiectasis, cystic fibrosis, bronchiolitis obliterans
Upper airway obstruction

When to see a doctor

Chronic cough, sputum, wheezing or breathlessness, especially in current or former smokers, should be checked with spirometry. Stopping smoking is the most effective way to slow lung function decline.

References

Global Initiative for Chronic Obstructive Lung Disease. Global Strategy for the Prevention, Diagnosis and Management of COPD: 2024 Report. GOLD; 2024. goldcopd.org
Stanojevic S, Kaminsky DA, Miller MR, et al. ERS/ATS technical standard on interpretive strategies for routine lung function tests. Eur Respir J. 2022;60(1):2101499. doi:10.1183/13993003.01499-2021
Graham BL, Steenbruggen I, Miller MR, et al. Standardization of spirometry 2019 update: an official American Thoracic Society and European Respiratory Society technical statement. Am J Respir Crit Care Med. 2019;200(8):e70–e88. doi:10.1164/rccm.201908-1590ST
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. doi:10.1183/09031936.00080312

This article is for general information and does not replace a consultation with a doctor. Measurements must be interpreted by a physician together with symptoms and other tests.

Published on 2 May 2024