tBPC oCare Pro100, Instructions For Use Manual

Page: 79 / 96

Taiwan Biophotonic Corporation
79
Pulse oximetry is based on the following two principles:
(1) Oxygenated hemoglobin and deoxygenated hemoglobin
have different optical absorbance in red and infrared
wavelength range (spectrophotometry).
(2) The volume of arterial blood in the tissue is periodically
changed with the heart beating. Therefore, the amount of
light absorbed by the changing volume of arterial blood is
also changed as well (photoplethysmography
) .
oCare
TM
Pro 100 is built with a reflectance oximetry sensor,
which consists of two or more light emitting diodes (LEDs)
and one or more photodiode light detector (PDs) located side
by side. Light beams are shone from LEDs through the skin to
the arteriolar bed of the tissue. The arteriolar bed absorbs
variable amounts of light during the pulsations. Changes in
light absorption during the pulsing cycle are measured by the
PDs as scattered lights are reflected back from the pulsating
arteriolar bed. Because oxygenated hemoglobin (HbO
2
) and
deoxygenated hemoglobin (Hb) have different optical
absorbance in red and infrared wavelength range, the beam of
infrared light is absorbed more by HbO
2
; the other beam of red
light is less absorbed by oxygenated blood and more strongly
absorbed by Hb.
The light absorbed by the blood also varies with the volume
variation in the arteriolar bed. During systole, light absorption
and blood volume increase to their maximum due to a new
pulse of arterial blood enters the arteriolar bed. During diastole,
light absorption and blood volume reach their minimum. Pulse
oximetry determines the SpO
2
on the difference between