Calculator Inputs
Required inputs are hemoglobin, arterial saturation, arterial oxygen pressure, and cardiac output. Add body size or venous values for indexed and extraction outputs.
Example Data Table
| Case | Hb (g/dL) | SaO2 (%) | PaO2 (mmHg) | CO (L/min) | Height (cm) | Weight (kg) | SvO2 (%) | PvO2 (mmHg) | CaO2 | DO2 | DO2I |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Example A | 13.5 | 98 | 95 | 5.4 | 172 | 70 | 72 | 40 | 18.02 mL O2/dL | 973.23 mL/min | 532.17 mL/min/m² |
Formula Used
CaO2 = (1.34 × Hb × SaO2) + (0.0031 × PaO2)
DO2 = CO × CaO2 × 10
BSA = √[(Height in cm × Weight in kg) ÷ 3600]
Cardiac Index = CO ÷ BSA
DO2I = DO2 ÷ BSA
CvO2 = (1.34 × Hb × SvO2) + (0.0031 × PvO2)
Estimated VO2 = CO × (CaO2 − CvO2) × 10
O2 Extraction Ratio = [(CaO2 − CvO2) ÷ CaO2] × 100
Hb is hemoglobin in g/dL. SaO2 and SvO2 are arterial and venous saturation fractions entered as percentages. PaO2 and PvO2 are oxygen pressures in mmHg.
CaO2 and CvO2 describe oxygen content in arterial and venous blood. DO2 shows total oxygen delivery each minute. Indexed results divide output by body surface area for size-adjusted comparison.
The dissolved oxygen term is usually much smaller than the hemoglobin-bound component, so hemoglobin, saturation, and cardiac output usually drive the largest changes.
How to Use This Calculator
- Enter hemoglobin, arterial saturation, arterial oxygen pressure, and cardiac output.
- Add height and weight to estimate body surface area automatically, or enter a manual BSA.
- Enter venous saturation and venous oxygen pressure when you want venous content, extraction, and estimated oxygen consumption.
- Add measured VO2 if you want a measured extraction ratio based on calculated oxygen delivery.
- Click the calculate button. The results will appear above the form.
- Use the CSV button for spreadsheet review or the PDF button for a shareable report.
- Review calculations together with bedside findings, direct monitoring, and your local clinical process.
Frequently Asked Questions
1) What does oxygen delivery mean?
Oxygen delivery is the amount of oxygen transported to tissues each minute. It depends mainly on cardiac output and arterial oxygen content, which is driven largely by hemoglobin and saturation.
2) Why is hemoglobin so important in this calculation?
Most oxygen in blood is carried while bound to hemoglobin. A change in hemoglobin often shifts arterial oxygen content more than a similar change in dissolved oxygen pressure.
3) Why does PaO2 usually change the result less?
The dissolved oxygen component is small because its coefficient is low. PaO2 still matters clinically, but it contributes less to total oxygen content than the hemoglobin-bound component in many situations.
4) What is the difference between DO2 and DO2I?
DO2 is total oxygen delivery per minute. DO2I is indexed oxygen delivery, which divides DO2 by body surface area so comparisons across different body sizes are easier.
5) When should I enter venous values?
Enter venous saturation and venous oxygen pressure when you want venous oxygen content, arteriovenous oxygen difference, estimated oxygen consumption, and an estimated extraction ratio.
6) Can pulse oximetry replace arterial saturation here?
It can be used as a practical surrogate in some settings, but measured arterial saturation or co-oximetry is preferable when precision matters or clinical conditions make pulse readings less reliable.
7) Why include body surface area?
Body surface area lets you index cardiac output and oxygen delivery. Indexed values can be more useful when comparing different patients or monitoring size-adjusted trends over time.
8) Can this calculator be used alone for diagnosis or treatment?
No. It is an educational and documentation aid. Final interpretation should rely on direct measurements, clinician judgment, the full patient picture, and local protocols.