Alveolar ventilation VA = (VT - VD) × f. With VT = 0.493 L, VD = 0.150 L, f = 14, VA is approximately:

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Alveolar ventilation VA = (VT - VD) × f. With VT = 0.493 L, VD = 0.150 L, f = 14, VA is approximately:

Alveolar ventilation is the air per minute that actually reaches the gas-exchanging parts of the lungs. It’s found by taking the effective tidal volume (the portion that reaches the alveoli) and multiplying by the breathing rate. Here, the effective tidal volume per breath is VT minus VD: 0.493 L − 0.150 L = 0.343 L. With a respiratory rate of 14 breaths per minute, VA = 0.343 L × 14 = 4.802 L/min, about 4.8 L/min. This uses the portion of air that participates in gas exchange, not the total tidal volume. Using the full tidal volume would overestimate alveolar ventilation (about 6.9 L/min), and using dead space alone would be far too low. So 4.8 L/min is the correct estimate.

Alveolar ventilation is the air per minute that actually reaches the gas-exchanging parts of the lungs. It’s found by taking the effective tidal volume (the portion that reaches the alveoli) and multiplying by the breathing rate. Here, the effective tidal volume per breath is VT minus VD: 0.493 L − 0.150 L = 0.343 L. With a respiratory rate of 14 breaths per minute, VA = 0.343 L × 14 = 4.802 L/min, about 4.8 L/min. This uses the portion of air that participates in gas exchange, not the total tidal volume. Using the full tidal volume would overestimate alveolar ventilation (about 6.9 L/min), and using dead space alone would be far too low. So 4.8 L/min is the correct estimate.

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