- % of oxygen saturated hemoglobin in blood stream
- “oxyhemoglobin”
- 95+% = healthy, 90-94% = watch out, <90% = danger generally measured using pulse oximeter
- shines red & infrared light through skin
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HbO2 (oxygenated hemoglobin) absorbs more infrared light & less red light
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Hb (deoxygenated hemoglobin) absorbs less infrared & more red light compare how much light of each wavelength is absorbed = relative ratio of HbO2 to Hb = SpO2
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\frac{\text{infrared light}}{\text{red light}} = \text{blood O2 reading}
- uses pulsing of blood (during heartbeats) to filter out static tissues (skin, bone) reflective pulse oximetry - photodetector (diode) & LED on same side. photodiode relies on backscattering of light - lower accuracy than pulse oxiometer devices with LED and photodetector on different sides but enough to capture trends **only works on radial artery (wont work on other parts of wrist)** need to program the LEDs based on skin tone, etc hardware requirements (???): - if pulse oxiometer method, red & IR - photodiode - motion detection to capture SpO2 when not in motion (similar to HRV?