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Pulse Oximeter is a non-invasive and painless test that measures your oxygen saturation level, or the oxygen levels in your blood. It can rapidly detect even small changes in how efficiently oxygen is being carried to the extremities furthest from the heart, including the legs and the arms. The Pulse Oximeter is a small, clip-like device that attaches to a body part, like toes or an earlobe. It’s most commonly put on a finger, and it’s often used in a critical care setting like emergency rooms or hospitals. Some doctors, such as Pulmonologists, may use it in office. All pulse oximeter probes (finger or ear) have light emitting diodes (LEDs) which shine two types of red light through the tissue. The sensor on the other side of the tissue picks up the light that is transferred through the tissues.

The oximeter can determine which of the haemoglobin is in pulsatile blood (arterial) and can then determine the SpO2 of arterial blood in the peripheral circulation.