Calculating Alveolar Ventilation: A Simple Guide

Alveolar ventilation (V_A) is the volume of fresh air reaching the alveoli per minute. It's calculated as:

V_A = (Tidal Volume − Dead Space) × Respiratory Rate

The simplified formula Tidal Volume × Respiratory Rate gives minute ventilation, not alveolar ventilation. For example, with a tidal volume of 400 mL and rate of 14 breaths/min, minute ventilation = 5,600 mL/min. Assuming ~150 mL dead space, alveolar ventilation ≈ (400−150) × 14 = 3,500 mL/min.

Accurate calculation requires subtracting dead space volume.