FIVC - forced 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 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.
- Most people find the inspiratory maneuver difficult to perform. The figure illustrates a few tidal breaths, the maximal exhalation, and then the FIVC maneuver recorded at faster paper speed.
- The measurement of the FIVC is almost invariably combined with that of the FIV1 (the volume that can be forcefully inhaled in one second starting from residual volume).
- By far the most common cause for a reduction in the FIVC is expiratory airway obstruction, occasionally restrictive lung disease.
- 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.