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VT tidal volume during normal, quiet breathing ERV expiratory reserve volume FRC functional residual capacity EVC expiratory vital capacity IVC inspiratory vital capacity TLC total lung capacity

RV - residual volume

The volume of the lung after maximal exhalation started from the functional residual capacity.

• In children and adolescents residual volume grows slightly faster than the total lung capacity, mostly on account of changes in chest geometry (references below).
• In healthy adults RV increases with age since a maximal expiration is increasingly impeded by airway closure, preventing dependent alveoli from emptying. In contrast, the total lung capacity does not change with age in adults. As a result the VC decreases with age in healthy subjects.
• Small airway pathology (inflammation, accumulation of secretions, hypertrophy and hyperplasia of glands and smooth muscles) and loss of lung elastic recoil (and therefore diminished elastic stretch of small airways) lead to premature airway closure during a maximal expiration; this causes the RV to increase, and the VC to decrease. Any factors that influence the TLC also affect the VC.

In patients with airway obstruction an FVC maneuver usually ends at a higher lung volume than a maximal expiration started from FRC level; only in the latter instance should end-expiratory volume be called RV.

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.