label: Abnormal alveolar volume
label_lc: abnormal alveolar volume
description: "Alveolar volume (VA) is a volume accessible during 10-second breath-hold, measured during a single breath maneuver. VA is calculated by knowing the fractional concentration of the tracer gas (eg helium) and the volume of the gas inhaled. VA = Vi*(Fi tracer/Fa tracer). In this equation, Vi = inspired volume of tracer gas, Fi tracer= inspired fraction of tracer gas, Fa tracer = alveolar (exhaled) fraction of tracer gas."