Pulse oximetry (diagnostic technique) (SpO₂)

Pulse oximetry is a noninvasive diagnostic technique that measures peripheral oxygen saturation (SpO₂) in blood using a small clip-on device. The device emits red (660 nm) and infrared (940 nm) light through tissue, typically a fingertip or earlobe, and a photodetector measures the differential light absorption by oxygenated and deoxygenated hemoglobin. SpO₂ readings are typically accurate within 2% of arterial oxygen saturation measured by blood gas analysis. Pulse oximetry is considered a vital sign and is widely used in clinical settings to detect hypoxemia and monitor patients before, during, and after surgery, as well as those with respiratory or cardiac conditions. While valuable for continuous, noninvasive monitoring, pulse oximetry cannot measure oxygen metabolism and has limitations in patients with carbon monoxide poisoning or abnormal hemoglobin variants.

Other names

Pulse oxOxygen saturation monitorFinger pulse oximeterSpO₂ measurement