How reliable are pulse oximetry findings?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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Answer

Answer

Although widely used, the practice of assessing oxygen desaturation by pulse oximetry is poorly standardized. The principle of oximetry measurement by spectrophotometry, although improving, is not as reliable as many practitioners believe. One side of the oximeter probe acts as a light-emitting source, and the other side acts as a photodetector. The probe is placed on a finger or earlobe. A forehead reflectance probe may also be used. The relative absorption of red (absorbed by oxygenated blood) and infrared (absorbed by deoxygenated blood) light of the pulsatile (systolic) component of the absorption waveform correlates to arterial blood oxygen saturation.


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