Blood oxygenation or Oxygen saturation (SpO2) is a measure of the oxygen saturation level in the arterial blood. Higher oxygen saturation indicates more oxygen in the blood. Oxygen saturation can change due to a number of factors, including lung or heart function and impacted externally by factors such as changes in altitude and/or pressure. It is useful to determine if an individuals respiration rate is bringing sufficient oxygen into the bloodstream, or perhaps 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.