Measured Versus Calculated Saturation - Henry Schein HS-Vet Instructions For Use Manual

This oximeter measures functional saturation-oxygenated
hemoglobin expressed as a percentage of the hemoglobin that can
transport oxygen. It does not detect significant amounts of
dysfunctional hemoglobin, such as carboxyhemoglobin or
methemoglobin.
In contrast, hemoximeter such as the IL482 report fractional
saturation-oxygenated hemoglobin expressed as a percentage of
all measured hemoglobin, including measured dysfunctional
hemoglobins.
To compare functional saturation measurements to those from an
instrument that measures fractional saturation, fractional
measurements must be converted.
8.3 Measured Versus Calculated
Saturation
When saturation is calculated from a blood gas partial pressure of
oxygen (PO ), the calculated value may differ from the SpO
2 2
measurement of a pulse oximeter. This usually occurs because the
calculated saturation was not appropriately corrected for the
effects of variables that shift the relationship between PO and pH,
2
the partial pressure of carbon dioxide (PCO ), 2,3-DPG, and fetal
2
hemoglobin.
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