A pulse oximeter, also known as a pulse ox, has been around for many years, but as technology has advanced, so has the pulse oximetry industry. A pulse oximeter is a medical device that is used to measure the percentage of oxygen saturation level in the blood stream of an individual. A pulse oximeter is designed to monitor blood oxygen saturation levels (SpO₂) indirectly without any blood sample. Therefore, an oximeter is also commonly categorized as a non-invasive medical device. A pulse oximeter can have additional features such as a plethysmograph, which measures changes in blood volume in the skin. A pulse oximeter is used by medical professionals to monitor patients SpO₂ constantly in clinical settings, along with the patients’ heart rate.

Recently, new portable pulse oximeters are available for use outside of the clinical settings. These new battery operated pulse oximeters are sized to be easily placed in one’s pocket or purse. They are widely used for in home on-spot SpO₂ readings, and also used by athletes for training as well. A portable pulse oximeter is designed to be clipped onto one’s finger for readings. Therefore, they are also referred to as fingertip pulse oximeters.

A pulse oximeter has been around for decades. It was first developed by Milliken in the 1940’s, which was used as the building block for today’s modern devices. It was Aoyagi at Nihon Kohden in 1972, who developed the first version of the modern pulse oximeter which used the ratio of red to infrared light absorption of pulsating components at the measuring spot. It was not until the early 1980’s when this new pulse oximeter was widely used in theUnited States.