Final answer:
The best measure of oxygen delivery to tissues is the arterial oxygen content (CaO2) because it accounts for both the hemoglobin-bound oxygen and the oxygen dissolved in plasma, providing a comprehensive assessment of oxygen availability to body tissues. Option C is correct.
Step-by-step explanation:
The best way to measure oxygen delivery to the tissues is through the calculation known as CaO2, which stands for the arterial oxygen content.
This measurement takes into account not just the partial pressure of oxygen in the blood (PaO2), but also the amount of hemoglobin available to carry oxygen (percent saturation, or SaO2) and its capacity to do so. The CaO2 formula integrates both the oxygen bound to hemoglobin and the oxygen dissolved in plasma, providing a comprehensive view of the oxygen delivery to tissues.
Arterial oxygen content (CaO2) is therefore a much more informative metric for clinicians than simply the oxygen saturation (SaO2) or the partial pressure of oxygen in the blood (PaO2), although pulse oximetry measuring SaO2 is often used for its convenience and noninvasiveness.
Understanding both the quantity of hemoglobin in the blood and how fully it is saturated with oxygen is critical for assessing a patient's oxygen delivery status, particularly in patients with insufficient hemoglobin that might lead to anemia, affecting tissue oxygenation.