Alveolar ventilation refers to which of the following?

• A. The volume of air that participates in gas exchange
• B. The largest volume of air that can be inspired in one breath
• C. The total volume of air inspired or expired in one minute
• D. The volume of air contained in the lung at the end of maximal inspiration

Answer: (A)

Alveolar ventilation is the portion of each breath that actually reaches the gas-exchange areas of the lungs and can participate in oxygen and carbon dioxide exchange. It represents the air available for gas exchange after subtracting the air that remains in the conducting airways (dead space). On a per-minute basis, it’s calculated as (tidal volume minus dead space) times the respiratory rate. This is different from minute ventilation, which is the total air moved in and out per minute regardless of whether it reaches the gas-exchange regions. It’s also not the maximum amount you can inspire in one breath, nor the total lung capacity. So the air that participates in gas exchange best describes alveolar ventilation.