Reference, Measurement principle – Minolta Pulsox-2 User Manual
Page 21
20
11. REFERENCE
Measurement Principle
Oxygen Saturation Monitor PULSOX-2 is a photometric instrument
that non-invasively and continuously measures the oxyhemoglobin
saturation of arterial blood (SpO
2
) and the pulse rate. SpO
2
is
described by the equation:
SpO
2
=
C (HbO
2
)
×
100 (% SpO
2
)
C (HbO
2
) + C (Hb)
where
C (Hb):
Concentration of reduced hemoglobin
C (HbO
2
):
Concentration of oxyhemoglobin
The light-absorption characteristics of reduced hemoglobin (Hb) are
very different from those of oxyhemoglobin. The PULSOX-2
measures the changes in the absorption of red and infrared lights
passing through the tissue to determine the SpO
2
of the blood. Thus,
this method is free from the effects of skin color, muscles, bones,
and veins.
Spectral Absorption of Hb and HbO
2
×
10
-6
cm
2
mole
1.0
HbO
2
Hb
0.5
600
700
800
900 nm
880
665
Red light
Infrared light
Wavelength
Absorption coef
ficient