The unit of oxygen capacity is typically expressed as mL O2/dL blood (milliliters of oxygen per deciliter of blood).
This unit reflects the amount of oxygen that can be carried by a specific volume of blood. Oxygen capacity is primarily determined by the concentration of hemoglobin in the blood. Each gram of hemoglobin can bind a fixed amount of oxygen, approximately 1.34 mL O2. Therefore, the more hemoglobin present in the blood, the greater its oxygen-carrying capacity.
For example, if a person has a hemoglobin concentration of 15 g/dL, their theoretical oxygen capacity would be approximately 15 g/dL * 1.34 mL O2/g Hb = 20.1 mL O2/dL blood.
It's important to note that this calculated value represents the maximum theoretical oxygen capacity. The actual oxygen content in the blood depends on other factors, such as the partial pressure of oxygen (PaO2) and the affinity of hemoglobin for oxygen.
