What is the role of arterial blood gas (ABG) in the workup of methemoglobinemia?

Updated: Dec 09, 2018
  • Author: Mary Denshaw-Burke, MD, FACP; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

The presence of methemoglobin can falsely elevate the calculated oxygen saturation when arterial blood gases (ABGs) are obtained. One possible clue to the diagnosis of methemoglobinemia is the presence of a “saturation gap.” This occurs when there is a difference between the oxygen saturation measured on pulse oximetry and the oxygen saturation calculated on the basis of ABG results.

The partial pressure of oxygen (PO2) value of the ABG measurement reflects plasma oxygen content and does not correspond to the oxygen-carrying capacity of hemoglobin. It should be within the reference range in patients with methemoglobinemia.


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