Pulse oximetry--principle and first experiences during anesthesia.

Oximetry is a photometric method for simple, non-invasive, and continuous measurement of the O2 saturation (SaO2). The addition of the word "pulse" indicates that, directed by a photo-electric plethysmogram, measurements are only performed during arterial pulsations. It appears from our first experiences with pulse oximetry during anesthesia that each decrease in SaO2 is indicated quickly and reliably. From a practical point of view it is important that the apparatus is connected quickly and easily, and that the O2 saturation is monitored continuously, also in those periods when normally no blood samples are taken. An additional advantage is that by means of the plethysmogram the circulation is also monitored.