CaO2 calculation: Hb 15 g/dL, SaO2 92%, PaO2 70 mmHg. What is CaO2?

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CaO2 calculation: Hb 15 g/dL, SaO2 92%, PaO2 70 mmHg. What is CaO2?

Oxygen content in arterial blood comes from two sources: oxygen bound to hemoglobin and dissolved oxygen in plasma. The calculation uses CaO2 = (Hb × 1.34 × SaO2) + (PaO2 × 0.003). With Hb = 15 g/dL, SaO2 = 92% (0.92), and PaO2 = 70 mmHg: - Bound oxygen = 15 × 1.34 × 0.92 = 18.492 mL/dL - Dissolved oxygen = 70 × 0.003 = 0.21 mL/dL - Total CaO2 ≈ 18.492 + 0.21 = 18.702 mL/dL, which rounds to about 18.70 mL/dL. This reflects how a lower saturation, even with normal Hb, reduces the amount of oxygen carried by hemoglobin, and the dissolved portion is relatively small.

Oxygen content in arterial blood comes from two sources: oxygen bound to hemoglobin and dissolved oxygen in plasma. The calculation uses CaO2 = (Hb × 1.34 × SaO2) + (PaO2 × 0.003).

With Hb = 15 g/dL, SaO2 = 92% (0.92), and PaO2 = 70 mmHg:

  • Bound oxygen = 15 × 1.34 × 0.92 = 18.492 mL/dL

  • Dissolved oxygen = 70 × 0.003 = 0.21 mL/dL

  • Total CaO2 ≈ 18.492 + 0.21 = 18.702 mL/dL, which rounds to about 18.70 mL/dL.

This reflects how a lower saturation, even with normal Hb, reduces the amount of oxygen carried by hemoglobin, and the dissolved portion is relatively small.

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