# Alveolar Ventilation Equation Calculator

Determines the total volume of fresh air entering the alveoli per minute.

Alveolar ventilation defines the total volume of air entering and leaving the respiratory zone (the alveoli) per minute and that participates in the gas exchange.

The first method determines alveolar ventilation based on tidal volume, pulmonary physiological dead space volume (from Bohr equation) and respiratory rate:

`VA = (Vt –Vd) x RR`

Where `Vd = Vt x (PACO2 – PETCO2) / PACO2`

The second method determines alveolar ventilation based on carbon dioxide output and arterial carbon dioxide tension:

`VA = 0.863 x VCO2 / PaCO2`

Tidal volume (Vt)
Respiratory rate (RR)
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Carbon Dioxide Output (VCO2)
Arterial CO2 Tension (PaCO2)
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Steps on how to print your input & results:

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.

## Determining alveolar ventilation

1) The first method determines alveolar ventilation based on tidal volume, pulmonary physiological dead space volume (from Bohr equation) and respiratory rate:

`VA = (Vt –Vd) x RR`

Where `Vd = Vt x (PACO2 – PETCO2) / PACO2`

Tidal volume can be estimated based on ideal body weight, via height and gender:

• `IBW male = 50kg + 2.3 x (height in inches – 60)`
• `IBW female = 45.5kg + 2.3 x (height in inches – 60)`
• Tidal Volume: ranges between 6 x IBW mL/kg IBW and 8 x IBW mL/kg.

2) The second method determines alveolar ventilation based on carbon dioxide output and arterial carbon dioxide tension:

`VA = 0.863 x VCO2 / PaCO2`

Alveolar Ventilation rate, measured in ml/min or L/min is a critical physiological variable in determining the concentrations of oxygen and carbon dioxide in functioning alveoli.

Normal ranges for the variables used are included in the table below:

 Variable Lower limit Higher limit Tidal volume (Vt) 400 mL 600 mL Physiological dead space volume (Vd) 100 mL 285 mL Respiratory rate (RR) 10 resp/min 16 resp/min Alveolar ventilation (VA) 3000 mL/min 5000 mL/min Carbon Dioxide Output (VCO2) 150 mL 320 mL Arterial CO2 Tension PaCO2 35 mmHg 45 mmHg Alveolar ventilation (VA) 3 L/min 5 L/min

## References

Mithoefer JC, Bossman OG, Thibeault DW, Mead GD. The clinical estimation of alveolar ventilation. Am Rev Respir Dis. 1968;98(5):868-71.

Blackie SP, Fairbarn MS, McElvaney NG, Wilcox PG, Morrison NJ, Pardy RL. Normal values and ranges for ventilation and breathing pattern at maximal exercise. Chest. 1991; 100(1):136-42.

Anaesthesia, Pain, Intensive Care and Emergency Medicine — A.P.I.C.E. Proceedings of the 19th Postgraduate Course in Critical Care Medicine Trieste, Italy — November 12–15, 2004.

Specialty: Pulmonology

System: Respiratory

Published On: May 14, 2020

Last Checked: May 14, 2020

Next Review: May 14, 2025