“Oxygen saturation is a term referring to the fraction of oxygen-saturated hemoglobin relative to total hemoglobin (unsaturated + saturated) in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal blood oxygen levels in humans are considered 95-100 percent. ... Levels below 80 percent may compromise organ function, such as the brain and heart” – Wikipedia. This class represents the measurement (or “clinical observation”) of the patient’s blood oxygen saturation level. This class re-defines the generic clinical Observation class to fix the observed characteristic to LOINC 2708-6 and to set the data type of the observation value to a Physical Quantity.