User Manual for Handheld Pulse Oximeter
28
Common Knowledge
1 Meaning of SpO
2
SpO
2
is the saturation percentage of oxygen in the blood, so
called O
2
concentration in the blood; it is defined by the
percentage of oxyhemoglobin (HbO
2
) in t he total
hemoglobin of the arterial blood. SpO
2
is an important
physiological parameter to reflect the respiration function; it
is calculated by the following method:
SpO
2
=HbO
2
/(HbO
2
+Hb)×100%
HbO
2
are the oxyhemoglobins (oxygenized hemoglobin),
Hb are those hemoglobins which release oxygen.
2 Principle of Measurement
Based on Lamber-Beer law, the light absorbance of a given
substance is directly proportional with its density or
concentration. When the light with certain wavelength
emits on human tissue, the measured intensity of light after
absorption, reflecting and attenuation in tissue can reflect
the structure character of the tissue by which the light
passes. Due to that oxygenated hemoglobin ( HbO
2
)and
deoxygenated hemoglobin (Hb) have different absorption
character in the spectrum range from red to infrared light
(600nm~1000nm wavelength), by using these
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