Pulse oxymetry; also Pulse ox, SpO2, or O2 Saturation. The use of laser light to measure the percentage of red blood cells in circulation carrying oxygen. A typical healthy SpO2 is 95% to 100%. Below 90% is considered pathological and requires treatment. Room air (RA) indicates that an SpO2 reading is based on a patient breathing local ambient atmospheric air, as opposed to patients breathing supplemental pure oxygen via a mask or other device.
(Definition provided by author.)