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VC - vital capacity

Vital capacity (VC): the volume change of the lung between a full inspiration and a maximal expiration. The maneuver may be performed in different ways:

1. The maneuver is performed rather slowly
  • Subdivision of lung volumes - vital capacityThe vital capacity is assessed during an inspiratory maneuver. Starting from end-tidal volume the subject expires maximally and subsequently makes a full inspiration. This is the inspiratory vital capacity (IVC).
  • The vital capacity is assessed during an expiratory maneuver. Starting from end-tidal volume the subjects makes a full inspiration and subsequently exhales maximally. This represents the expiratory vital capacity (EVC), or ‘slow vital capacity’ (SVC) in the Anglo-American literature.
2. The maneuver is performed with maximal force
  • If the subject first fills the lung to the fullest (i.e. to total lung capacity), and then exhales forcefully and completely to residual volume, the volume change of the lung is the forced vital capacity (FVC); it would be more correct to speak of forced expiratory vital capacity (FEVC).
  • If the subject first exhales fully to residual volume, and then inhales forcefully and fully to total lung capacity, the volume change of the lung is the forced inspiratory vital capacity (FIVC) .

In healthy subjects the vital capacities measured according to these different procedures are nearly the same. In patient with obstructive lung disease, however, the vital capacity obtained during expiratory maneuvers is smaller than when obtained upon inspiration:

IVC > EVC = SVC > FVC.

You should therefore always note which VC has been assessed.


Subdivision of lung volumes - inspiratory vital capacityIVC - inspiratory vital capacity

The volume change of the lung between a maximal expiration to residual volume and a full inspiration to total lung capacity. The inspiratory vital capacity is assessed during an inspiratory maneuver, which is not performed forcefully.

The largest of 3 technically satisfactory maneuvers, which differ by no more than 5% or 150 mL (the larger of the two) from the next largest IVC, should be reported. If the difference is larger, then perform up to 8 measurements; if the repeatability criterion is still not met then report the largest IVC with a note that reproducible measurements could not be obtained.

 


Subdivision of lung volumes - expiratory vital capacityEVC - expiratory vital capacity
SVC - slow vital capacity

The volume change of the lung between a full inspiration to total lung capacity and a maximal expiration to residual volume.

The expiratory vital capacity is assessed during an expiratory maneuver, which is not performed forcefully. This index is called the ‘slow vital capacity’ in Anglo-American literature. The selection criteria are the same as for the IVC.

 


FVC - forced expiratory vital capacity

Forced vital capacity, FVCThe volume change of the lung between a full inspiration to total lung capacity and a maximal expiration to residual volume. The measurement is performed during forceful exhalation; the preceding maximal inhalation need not be performed forcefully. The volume assessed is the forced expiratory vital capacity (FEVC), commonly called forced vital capacity (FVC). The maneuver is almost invariably performed in conjunction with the assessment of the FEV1 and of maximum expiratory flow-volume curves. In patients with obstructive lung disease FVC < EVC < IVC.

If 8 maneuvers have not led to a FVC or FEV1 meeting the above requirements for reproducibility, then further attempts are useless:

  1. Ferris BG Jr, Speizer FE, Bishop Y, Prang G, Weener J.
    Spirometry for an epidemiologic study: deriving optimum summary statistics for each subject. Bull Europ Physiopathol Respir 1978; 14: 145-166.
  2. Kanner RE, Schenker MB, Munoz A, Speizer FE. Spirometry in children: methodology for obtaining optimal results for clinical and epidemiological studies. Am Rev Respir Dis 1983; 127: 720-724.

 


FIVC - forced inspiratory vital capacity

Forced inspiratory vital capacityThe volume change of the lung between a maximal expiration to residual volume and a full inspiration to total lung capacity. The measurement is performed during forceful inhalation; the preceding maximal exhalation need not be performed forcefully. The volume assessed is the forced inspiratory vital capacity (FIVC).

At the present time forceful exhalations and inspirations are often performed in immediate succession, so that maximal expiratory and inspiratory flow-volume curves can be recorded. It matters in which order the maneuvers are performed. In a patient with pronounced airway obstruction an FIVC performed after an FVC maneuver almost invariably leads to the FIVC being larger than the FVC. If the order is reversed the FIVC and FVC are about the same: the FIVC assessed immediately after an FVC maneuver should therefore not go on record as an IVC.


Recommended procedures

  1. Quanjer PhH, Tammeling GJ, Cotes JE, Pedersen OF, Peslin R, Yernault JC. Lung volumes and forced ventilatory flows. Official Statement of the European Respiratory Society. Eur Respir J 1993; 6 suppl. 16: 5-40. Erratum Eur Respir J 1995; 8: 1629.
  2. Miller MR et al. Standardisation of spirometry. ATS/ERS task force: standardisation of lung function testing. Eur Respir J 2005; 26: 319-338. Erratum Eur Respir J 1995; 8: 1629.
  3. Miller MR et al. Standardisation of spirometry. ATS/ERS task force: standardisation of lung function testing. Eur Respir J 2005; 26: 319-338.
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