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How Pulse Oximeters Work

Pulse oximeter measures the percentage of oxygen in red blood cells, also known as oxygen saturation. Oxygen saturation usually tells how sufficient oxygen is being transferred to different parts of the body.


Pulse oximetry is a clip-on device that measures oxygen saturation. It comes as a small unit with a built-in finger /toe clip, or a small handheld device that has a wire probe that can be attached or be applied to finger, toe, or earlobe. When infrared light from the device passes through the blood in the finger (toe or earlobe), it measures changes of light absorption in the blood. The reading of oxygen saturation is displayed as SpO2.


Typically, 95 – 100 percent of the oxygen saturation level is considered normal for most healthy individuals. Having the oxygen saturation level below this range for a long time will put strain on heart and brain, and need attention. However, for those people with heart or lung problems may have lower readings. It is important to keep in mind that pulse oximeter is for measurement ONLY, not for any diagnosis or treatment. Always consult with your physicians before any preventive action.

Interested in purchasing your own Pulse Oximeter? View our collection of easy to use, clinical grade monitoring devices here.

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