oxygen saturation test (OK-sih-jen SA-chuh-RAY-shun…)
A test that measures the amount of oxygen being carried by red blood cells. One method uses a device that shines light through a finger. The device measures the amount of oxygen in the blood based on the way red blood cells carrying oxygen absorb and reflect light. In another method blood is taken from an artery and the amount of oxygen is measured directly. An oxygen level that is lower than normal may be a sign of lung disease or other medical conditions.