The extra volume of air that can be inspired with maximal effort after reaching the end of a normal, quiet inspiration. Common abbreviation is irv. ... (12 Dec 1998) ... 
the maximal amount of gas that can be inhaled from the end-inspiratory position.
(IRV) Type: Term Definitions: 1. the maximal volume of air that can be inspired after a normal inspiration; the inspiratory capacity less the tidal volume. Synonyms: complemental air