Pulse oximetry: Its origin and development

Pulse oximetry is a method to monitor oxygen saturation of the arterial blood noninvasively and continuously. This method has become indispensable in almost all aspects of modern medical practice, especially for life support in anesthesia. This is an unexpected great pleasure for me as the inventor of pulse oximetry. But I believe that pulse oximetry is no more than the first fruits of a new concept of noninvasive monitoring of the blood which might be called "pulse spectro-photometry". I would like to explain the origin of this idea and its development as the pulse oximeter, together with a new application to the dye dilution method.