PULSE OXIMETRY…Pulse oximeters measure how much of the hemoglobin in blood is carrying oxygen (oxygen saturation). The pulse oximeter works out the oxygen saturation by comparing how much red light and infra red light is absorbed by the blood. Depending on the amounts of oxy Hb and deoxy Hb present, the ratio of the amount of red light absorbed compared to the amount of infrared light absorbed changes.
OXYGEN SATURATION…….Oxygen saturation simply refers to the percentage of the available hemoglobin that carries oxygen.
UNSATURATED…..haemoglobin is unsaturated when it is not carrying oxygen.
OXYHAEMOGLOBIN….refers to the Hb molecule when it has oxygen bound to it. HbO8
DEOXYHAEMOGLOBIN…. Refers to the Hb molecule with no oxygen bound to it
LIGHT SOURCE.. Where the light is generated or comes from. The oximeter has two sources, one releasing visible light, the other infrared.
DETECTOR……..to determine or measure.
RED LIGHT. Red light is part of the visible spectrum. It is an electromagnetic wave with a wavelength of 650 nm.
INFRA-RED RADIATION. This is also an electromagnetic wave, however it has a longer wavelength. That is 950 nm.
ABSORBANCE…molecules can take in or absorb light energy through vibrating, rotating or through bons stretching and contracting. The key here is
Oxy Hb absorbs more infrared light than red light
Deoxy Hb absorbs more red light than infrared light
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