Co-oximetry reports fractional saturation as the percentage of which species relative to total hemoglobin?

Co-oximetry reports fractional saturation as the percentage of which species relative to total hemoglobin?

• A. HbO2 and Hb only
• B. HbO2, MetHb, COHb, and Hb
• C. HbO2, Hb, MetHb only
• D. COHb and MetHb only

Answer: (B)

Co-oximetry quantifies the amount of each distinct form of hemoglobin and expresses how much of the total hemoglobin is in a given form. The total Hb includes all detectable species: oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), methemoglobin (MetHb), and carboxyhemoglobin (COHb). Fractional saturation for HbO2 is therefore HbO2 divided by the sum of HbO2, Hb, MetHb, and COHb, times 100. In other words, the fractions reported are for HbO2, MetHb, COHb, and Hb relative to total Hb. That makes the option listing all four forms the correct one.

Co-oximetry quantifies the amount of each distinct form of hemoglobin and expresses how much of the total hemoglobin is in a given form. The total Hb includes all detectable species: oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), methemoglobin (MetHb), and carboxyhemoglobin (COHb). Fractional saturation for HbO2 is therefore HbO2 divided by the sum of HbO2, Hb, MetHb, and COHb, times 100. In other words, the fractions reported are for HbO2, MetHb, COHb, and Hb relative to total Hb. That makes the option listing all four forms the correct one.