Pulse oximetry: an overview.

Pulse oximetry has emerged as a very common and useful method to measure oxygen saturation since it was first described by Takuo Aoyagi in 1974. It measures the oxygen saturation of haemoglobin in the arterial blood and the pulse rate. It is an indirect indicator of cardiac output. It also gives an audible signal varying in pitch depending on the oxygen saturation. It displays a plethysmographic image and also gives a digital readout. The following is an overview of the device and an examination of its applications.