Finger Pulse Oximeter: How to use one correctly

Finger Pulse Oximeter Operation: Finger oximeters analyze blood oxygen saturation levels by determining the ratio of oxygenated to deoxygenated hemoglobin as it passes through a fingertip. Using the ratios of pulsatile to total red light transmitted through the finger, divided by the identical ratio for infrared light transmitted, oximeter readings should theoretically be independent of variables that affect light transmission through the finger. Sadly, this theory doesn’t hold up well under real world situations.