[The functional principle, reliability and limitations of pulse oximetry]

Pulse oximetry has found wide-spread application in recent years. It is simple, noninvasive and continuous method for measuring arterial oxygen saturation. This survey deals with the history of pulse oximetry, its technical foundations, the differential indications and contraindications, and its limitations and possibilities for error. A number of suggestions are made for improving the accuracy of measurement and the interpretation of values. These include improved calibration, including low saturation ranges (below 70%) and the development of pulse oximeters that measure with more than two wavelengths, which would eliminate measuring errors due, for example, to carboxyhemoglobin.