EDAN H100B User Manual - page 76
H100B Pulse Oximeter User Manual
- 68 -
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 0oxygen saturation of arterial
hemoglobin, the oximeter uses the pulsatile nature of
arterial flow.
During systole, a new pulse of arterial blood enters the
vascular bed, and blood volume and light absorption
increase. During diastole, blood volume and light
absorption reach their lowest point.
The oximeter bases its SpO
2
measurements on the
difference between maximum and minimum absorption
(measurements at systole and diastole). By doing so, it
focuses on light absorption by pulsatile arterial blood,
eliminating the effects of non-pulsatile absorbs such as
tissue, bone and venous blood.