Alveolar ventilation (VA) is the amount of air that reaches the alveoli in the lungs and participates in gas exchange per minute. It's a crucial measure of effective breathing, as it accounts for the dead space in the respiratory system – the parts of the airway that don't participate in gas exchange (like the trachea and bronchi). Alveolar ventilation is more representative of the body's actual oxygen intake and carbon dioxide removal than the total minute ventilation.
The formula to calculate Alveolar Ventilation Rate (VA) is:
VA = (Tidal Volume – Dead Space Volume) × Respiratory Rate
Where:
VA = Alveolar Ventilation Rate (mL/min)
Tidal Volume (VT) = The volume of air inhaled or exhaled in one normal breath (mL).
Dead Space Volume (VD) = The volume of air in the respiratory system that does not participate in gas exchange (mL). An estimated value for functional dead space is often around 1 mL/kg of ideal body weight or a fraction of tidal volume. For simplicity in this calculator, we will use an input field for VD.
Respiratory Rate (RR) = The number of breaths taken per minute.