In the early 1980s pulse oximetry was introduced and is now commonplace in the emergency and acute care market. It has become the standard non-invasive method of determining arterial oxygen saturation because of its simple functionality and high clinical value. Pulse oximetry has been on the increase in primary care settings as well. Small, inexpensive pulse oximeter units have changed the way primary care physicians evaluate, manage, and treat patients. It provides the physician with a quantitative assessment and measurement with which to manage patients’ chronic and acute illnesses.