Monday September 25, 2006
CO-OXIMETRY


Interpretation of ABG can be divided into measured and calculated values. The PH, PaO2 and PaCO2 are the measured values and HCO3 and SaO2 are calculated values. As the SaO2 is a calculated value, it does not reflect Methemoglobin and Carboxyhemoglobin levels and can misguide the management.

The most accurate method of tracking the Methemoglobin and Carboxyhemoglobin is the Co-oximetry. The principle of operation is related to the Beer-Lambert law, which states that the amount of light absorbed by a substance is directly related to the concentration of the substance. The co-oximeter uses various wavelengths of light to measure the concentration of oxyhemoglobin, reduced hemoglobin, Methemoglobin and Carboxyhemoglobin.
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