Final answer:
Percent saturation is monitored using a pulse oximeter, a device that measures the amount of oxygen that hemoglobin in the blood is carrying. The results are presented as a percentage of the maximum amount of oxygen that hemoglobin can carry. Lower percentages indicate low blood oxygen levels. Oxygen levels can also be measured in terms of partial pressure of oxygen.
Step-by-step explanation:
Percent saturation is normally monitored using a device known as a pulse oximeter, which is applied to a thin part of the body, typically the tip of the patient's finger. The device works by sending two different wavelengths of light (one red, the other infrared) through the finger and measuring the light with a photodetector as it exits. Hemoglobin absorbs light differentially depending upon its saturation with oxygen. The machine calibrates the amount of light received by the photodetector against the amount absorbed by the partially oxygenated hemoglobin and presents the data as percent saturation.
Normal pulse oximeter readings range from 95-100 percent. Lower percentages reflect hypoxemia, or low blood oxygen. The term hypoxia is more generic and simply refers to low oxygen levels. Oxygen levels are also directly monitored from free oxygen in the plasma typically following an arterial stick. When this method is applied, the amount of oxygen present is expressed in terms of partial pressure of oxygen or simply pO2 and is typically recorded in units of millimeters of mercury, mm Hg.