User Manual for Fingertip Oximeter
19
B SpO
2
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 the 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
)