Ventilatory Ratio (VR)
Ventilatory ratio (Sinha 2009): measured minute ventilation × PaCO₂ divided by predicted values; a ratio above 1 marks impaired CO₂ clearance / a larger dead-space fraction.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Measured minute ventilation
- 9000 mL/min
- Measured PaCO₂
- 50 mmHg
- Height
- 175 cm
- Sex
- Male
Result: Ventilatory ratio 1.7 — elevated (normal ≈ 1): larger dead-space fraction.
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Meaning
- Normal ≈ 1; higher marks worse efficiency / larger dead space; VR > 2 tracks ARDS mortality.
What you enter
- Measured minute ventilation
- Measured PaCO₂
- Height
- Sex (for predicted body weight)
How this is calculated
- Formula
- VR = (measured minute ventilation × measured PaCO₂) / (predicted body weight × 100 × 37.5), ARDSNet PBW.
Sinha P, Fauvel NJ, Singh S, Soni N. Ventilatory ratio: a simple bedside measure of ventilation. Br J Anaesth. 2009;102(5):692-697. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.