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Terminology

You may hear some of the following terms:

SpO₂ = This is an indirect measurement of O₂ in the blood, usually using and Oximeter device on the patients fingertip. It provides an estimate of the blood O₂ in a capillary below the nail. Abnormal SpO2 is below 95% without pre-existing lung condition.
Those with a pre-existing lung condition may have lower normal values e.g. abnormal SpO2 may be less than 92%.
SaO₂ = This is a direct measurement of the O₂ in the arterial blood gases. It measures the percentage of the oxyhaemoglobin. Normal levels should be between 95 to 100%.
Haemoglobin = Haemoglobin is a red protein responsible for transporting oxygen in the blood it can be in two states oxygenated or deoxygenated.

References

Harper J. Post-anaesthesia care unit nurses' knowledge of pulse oximeter. J Nurses Staff‘ Dev 2004; 20(4):177-180
AttinM, CardinS, DeeV, DoeringL, DunnD, EricksonVetaI. An educational project to improve knowledge related to pulse oximeter. Am J Crit Care 2002; 11(6):529-534.