Tests for airway flow rates, lung volume, and lung capacity provide information about the severity of airway obstruction and serve as an index of dynamic function. The lung volume at which the flow rates are measured is useful for identifying a central or peripheral location of airway obstruction.
Combinations of two or more volume measurements are termed capacities. These volumes and capacities are shown graphically in Figure 14.1. Measurement of these values can provide information about the degree of air trapping or hyperinflation in the lungs.
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