SpO2 stands for peripheral capillary [[oxygen saturation]]. It is a measure of the oxygen saturation level in the blood and is usually expressed as a percentage. The measurement is typically obtained using a [[pulse oximeter]], which is a non-invasive [[medical device]] that clips onto a finger or other part of the body and uses light to measure the amount of [[oxygen]] in the blood. A normal SpO2 reading is typically between 95% and 100%, and values below 90% may indicate a need for medical attention, as low [[oxygen]] [[saturation]] levels can lead to serious health problems.