How is carbon monoxide hemoglobin (COHb) typically measured?

Carbon monoxide hemoglobin (COHb) levels are typically measured using a co-oximeter or hemoximeter. These specialized devices are designed to analyze multiple forms of hemoglobin in addition to measuring oxygen saturation, including carboxyhemoglobin, meth hemoglobin, and oxyhemoglobin.

The co-oximeter uses specific wavelengths of light absorption to differentiate these various forms of hemoglobin, thereby accurately quantifying the amount of carbon monoxide bound to hemoglobin. This precise measurement is critical in cases of suspected carbon monoxide poisoning, as it helps determine the severity of exposure and guides appropriate treatment.

Other measurement methods, such as standard blood gas analyzers and pulse oximeters, are not suitable for determining COHb levels. While a pulse oximeter provides information on oxyhemoglobin saturation, it cannot distinguish between oxyhemoglobin and carboxyhemoglobin, leading to potentially misleading results in cases of carbon monoxide exposure. Similarly, a complete blood count (CBC) test does not measure hemoglobin types; rather, it gives an overall picture of blood components such as red and white blood cells. Thus, the co-oximeter is the appropriate tool for accurately assessing COHb levels in patients.