Clinical Significance

CO-oximetry
The ABL analyzer measures ctHb, sO₂, FO₂Hb, FCOHb, FMetHb, and FHHb. Measurement of CO-oximetry parameters expands the traditional blood gas analysis. These parameters give information on oxygen uptake in the lungs, the oxygen transport capability of the blood and the ability of the blood to release oxygen to the tissues.

ctHb (Concentration of total hemoglobin)
Hemoglobin transports the oxygen around the body. Each hemoglobin molecule can carry four oxygen molecules. ctHb is a direct measurement of the blood's potential to transport oxygen. Low tHb may lead to faintness.

FO₂Hb (Fraction of oxyhemoglobin)
FO₂Hb is the fraction of oxygenated hemoglobin (the form of hemoglobin that carries oxygen) of the total amount of hemoglobin. FO₂Hb can be used to evaluate the oxygen transport capacity.

FCOHb (Carboxyhemoglobin)
FCOHb is the fraction of carboxyhemoglobin of the total amount of hemoglobin. It carries CO instead of O₂, thereby blocking the capability of releasing oxygen to the tissue. CO's affinity to Hb is 210 times higher than that of O₂. CO comes from exhaust gases and tobacco smoke.

FMetHb (Methemoglobin)
Methemoglobin is formed when blood is exposed to oxidizing agents, oxidizing the iron atom Fe²⁺ to Fe³⁺. MetHb has a very low affinity to O₂. The alteration is caused by certain medicines and organic solvents. FMetHb is the fraction of methemoglobin of the total amount of hemoglobin.