In the O2 content equation, which term represents dissolved oxygen content?

In the O2 content equation, which term represents dissolved oxygen content?

• A. 1.39 × Hemoglobin × Arterial Saturation
• B. 0.003 × PaO2
• C. 1.39 × Hemoglobin × PaO2
• D. Hemoglobin × PaO2

Answer: (B)

Dissolved oxygen content is the portion of O2 that is physically dissolved in the plasma, driven directly by the arterial oxygen tension. Its amount is determined by the solubility of O2 in blood, about 0.003 mL O2 per dL of blood for each mmHg of PaO2, so the dissolved part is 0.003 × PaO2. This is why that term uniquely represents the dissolved O2 content. The other terms describe oxygen bound to hemoglobin, which depends on hemoglobin concentration and how saturated it is with O2, not on PaO2 directly.

Dissolved oxygen content is the portion of O2 that is physically dissolved in the plasma, driven directly by the arterial oxygen tension. Its amount is determined by the solubility of O2 in blood, about 0.003 mL O2 per dL of blood for each mmHg of PaO2, so the dissolved part is 0.003 × PaO2. This is why that term uniquely represents the dissolved O2 content.

The other terms describe oxygen bound to hemoglobin, which depends on hemoglobin concentration and how saturated it is with O2, not on PaO2 directly.