H100N Pulse Oximeter User Manu Principles of Operation
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Pulse oximetry is based on two principles:
Oxyhemoglobin and deoxyhemoglobin differ in
their absorption of red and infrared light
(spectrophotometry).
The volume of arterial blood in tissue (hence light
absorption by the blood) changes during the pulse
(plethysmography).
The oximeter determines SpO
2
by passing red and
infrared light into an arteriolar bed and measuring
changes in light absorption during the pulsatile cycle.
Red and infrared low-voltage light-emitting diodes (LED)
serve as light sources; a photonic diode serves as the
photo detector.
Because oxyhemoglobin and deoxyhemoglobin differ in
light absorption, the amount of red and infrared light
absorbed by blood is related to hemoglobin oxygen
saturation. To identify the oxygen saturation of arterial
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