What is the formula to calculate the content of arterial oxygen (CaO2)?

The formula for calculating the content of arterial oxygen (CaO2) is essential for understanding how much oxygen is transported in the blood. The correct formula incorporates both the bound oxygen and the dissolved oxygen in the plasma.

CaO2 is determined by two main components: the amount of oxygen bound to hemoglobin and the amount dissolved in plasma. The first part of the formula, (hgb x 1.34) x SaO2, calculates the oxygen bound to hemoglobin, where hemoglobin (hgb) is multiplied by the oxygen-carrying capacity of hemoglobin (1.34 ml O2/g) and the saturation of hemoglobin with oxygen (SaO2).

The second part of the formula, (PaO2 x 0.003), adds the amount of oxygen dissolved in the plasma, which is related to the partial pressure of oxygen in arterial blood (PaO2). The factor of 0.003 represents the solubility coefficient for oxygen, indicating how many milliliters of oxygen dissolve in each milliliter of blood per mmHg of PaO2.

By combining these two components, the formula B accurately represents the total arterial oxygen content, providing a comprehensive measure of oxygen transport in the bloodstream