Handheld pulse oximeter user’s manual
Chapter 5 Measuring SpO2
5.1 Introduction
The measurement of oxygen saturation of arterial blood
(also known as peripheral oxygen saturation, usually
shortened to SpO
2
) relies on the principles of light spectra
and volume tracing. An LED in the oximeter emits light rays
through the body, wherever the probe is used, e.g. through
the finger, at two different specific wavelengths. Each of
these is selectively absorbed by oxygenated hemoglobin and
deoxyhemoglobin in the blood. An optical receptor measures
the changes in the light intensity after the light passes
through the capillary network and estimates the ratio of
oxygenated hemoglobin and the total hemoglobin.
1
SpO
2
% =
×
100%
oxygenated hemoglobin
oxyhemo deoxyhemoglobin
