SpO2 monitoring is a non-invasive and painless way of measuring the oxygen saturation in a persons blood. It is a measure of blood oxygen saturation, which is the amount of oxygen carried by red blood cells in the circulatory system. SpO2 monitoring is done using a pulse oximeter, which consists of a computerized monitor and a probe that is attached to a patients finger, toe, nostril, or earlobe. The probe uses light to measure how much oxygen is in the blood, and the monitor displays a reading of how saturated the patients blood is with oxygen. SpO2 monitoring is a quick and non-invasive technique that provides near-immediate readings. It is used to monitor patients with lung and heart disorders, who are at risk of low levels of blood oxygen. SpO2 monitoring is also used to check the health of a person with any condition that affects blood oxygen levels, such as sleep apnea. Smartwatches and fitness trackers such as the Samsung Galaxy Watch 4, Apple Watch Series 7, Fitbit Versa 3, and Xiaomi Mi Band 6 offer SpO2 monitoring.