Arterial Oxygen Content (CaO₂) calculator
Result
18.5mL/dL
Normal
Normal ~18–21 mL/dL. Dissolved O₂ (0.0031×PaO₂) usually <3% of total.
How to use it
- 1
Hgb from FBC; ABG for SaO₂ and PaO₂. Ensure arterial sample.
- 2
Formula. CaO₂ = 1.34 × Hgb × (SaO₂/100) + 0.0031 × PaO₂.
- 3
Low Hgb impacts CaO₂ as much as SpO₂. Anaemia reduces O₂ carrying capacity despite normal SpO₂.
When to use it
- O₂ delivery calculation
- DO₂ = CO × CaO₂ × 10. Low DO₂ guides transfusion vs. inotropes.
- Hypoxaemia vs. anaemia
- Separates failure to load O₂ (SpO₂ problem) from failure to carry it (Hgb problem).
- Transfusion trigger
- CaO₂ < 16 mL/dL with symptoms supports transfusion.
A reference for clinicians and students, not medical advice. A score supports a decision; it does not make one. Check every result against the patient in front of you and your local protocol.
At a glance
- Specialty
- Pulmonology
- Inputs
- 3
- Type
- Formula
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