The current status of pulse oximetry

Abstract

The history of the development of pulse oximetry is outlined and the principle of how the apparatus works is described. The instrument detects hypoxic hypoxia and the shape of the oxygen dissociation curve means that the minimum saturation alarm should be set at 94% in anaesthetic usage. It is accurate to within 2% and is usually unaffected by racial pigmentation, but accuracy can be aflected in low perfusion states, hypotherrnia and in the presence of abnormal forms of haemoglobin and pigments in the blood. Its clinical evaluation in the operating theatre and intensive care unit is reported. It was found to be useful and reliable and would appear to have logistical and other advantages over current methods of detecting hypoxia. Pulse oximetry may make a signijcant contribution to the safety of anaesthetic practice.