According to John Hopkins Medicine, Sp02 refers to pulse oximetry, or the measurement of the specific oxygen content of a patient's blood. This is measured using a non-invasive diagnostic device known as a pulse oximeter.
John Hopkins Medicine describes a pulse oximeter as a small clip-like device usually placed on a patient's fingertip. It contains visible and infrared light sources on one side and visible and infrared light detectors on the opposite side. The lights shine through the finger and are picked up by the sensors on the far side. As the light passes through the fingertip, the light interacts with the blood flowing through the blood vessels in the fingertip. These lights interact differently when passing through oxygen-rich arterial hemoglobin and oxygen-poor venous hemoglobin. The sensor on the far side of the clip detects these differences and uses them to determine the specific oxygen content of the blood in that extremity, a measurement expressed as SpO2. This is useful to determine if a patient's respiration is bringing sufficient oxygen into the blood stream, or if there is a lack of blood flow to an extremity. The Mayo Clinic states that the normal SpO2 values for a healthy individual are between 95 and 100 percent.