Basic and Clinical Sciences (BCSE) 2025 – 400 Free Practice Questions to Pass the Exam

The formula for calculating the oxygen content in arterial blood, known as CaO2, is:

CaO2 = (1.34 x [Hb] x %sat) + (0.003 x PaO2).

In this equation, 1.34 represents the amount of oxygen (in mL) that can be carried by one gram of hemoglobin, [Hb] stands for the hemoglobin concentration in grams per deciliter, %sat is the hemoglobin saturation with oxygen, and PaO2 is the partial pressure of oxygen in arterial blood, typically measured in mmHg.

The first component of the formula calculates the oxygen carried physically by hemoglobin in the blood, while the second part accounts for the small amount of oxygen dissolved directly in the plasma (which is calculated as approximately 0.003 mL of oxygen per mmHg of PaO2).

The choices presented include various combinations of these components and their multipliers or factors. The correct formula accurately reflects the contribution from both hemoglobin-bound oxygen and dissolved oxygen, supporting the complete calculation of arterial blood's oxygen content. Thus, the choice that provided the correct formula precisely matches the accepted physiological equation, making it the accurate answer.