One second capacity

The (expiratory) forced expiratory volume FEV ₁ ( engl .: F orced E xpiratory V olume in 1 second) is the rapidly exhaled by people within the first second volume with great effort. The diagnostic method for determining FEV ₁ is called the Tiffeneau test or breath test.

The one-second capacity is a dynamic, time-dependent measurement parameter (volume) in lung function diagnostics. The basic examination in breathing technology is spirometry . Breathing flow rates and - as an integral - the lung volumes at the patient's mouth are measured . After normal resting breathing, the patient exhales to the maximum (expired) and then breathes in to the maximum (inspired); the difference is the inspiratory vital capacity (VC). The patient then exhales as quickly as possible from the maximum inspiratory position. The volume exhaled in one second represents the absolute forced expired volume of the first second (FEV ₁ = one-second capacity), the maximum expired volume is called the forced vital capacity (FVC). The FEV ₁ / FVC ratio is usually ≥ 75%.

Above all, the one-second capacity related to the forced vital capacity = FEV ₁ / FVC × 100 (%) is assessed. It is referred to as the relative one-second capacity , the relative second capacity or Tiffeneau index and Tiffeneau value and is normally ≥ 75%, in older patients ≥ 70%. FEV ₁ is the parameter for an obstruction (narrowing) of the lower ( intrathoracic ) airways. It is accordingly limited in obstructive airway diseases such as bronchial asthma , COPD or emphysema . The individual measured values ​​are related to the target value standard tables of the European Coal and Steel Community , depending on age, gender, height and weight .

The FEV _{1 is also} reduced in restrictive lung diseases such as pulmonary fibrosis . Since restrictive lung diseases are characterized by the restricted elasticity of the lungs, the vital capacity is reduced at the same time, so that the Tiffeneau value is normal.

If there is severe obstruction, more air remains in the lungs after rapid, maximum exhalation (increased residual volume (RV)), so that the forced vital capacity is correspondingly reduced; there is a shift in the position of the respiratory system due to overinflation. The one-second capacity can appear "normal" despite the obstruction.

The disadvantage of the one-second capacity measurement is the dependence on patient cooperation. This is particularly problematic in the case of occupational health reports ("Blow a lot - little money, blow a little - a lot of money") or if the measurement is carried out on children.

See also

• Allergy test
• Lung function

literature

• Peter Angerer: Allergology Handbook: Basics and Clinical Practice; 181 tables . Schattauer, Stuttgart / New York 2006, ISBN 3-7945-1972-8

Individual evidence

1. ↑ Gillissen A, et al. : Clinical significance of the forced one-second capacity (FEV1) in chronic obstructive pulmonary disease (COPD) . In: Medical Clinic . 104, No. 2, February 2009, pp. 119-124. doi : 10.1007 / s00063-009-1023-9 . PMID 19242663 .
2. ↑ Pulmonary function test in occupational medicine ( memento of the original from April 3, 2017 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Guideline of the German Society for Occupational Medicine and Environmental Medicine eV (DGAUM) 

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