History and recent developments in pulse oximetry.

To honour Siggaard-Andersen's role in the development of accurate blood oximetry, this paper was abstracted from a recent review and survey of over 750 publications of pulse oximetry. Pulse oximetry usage has become nearly universal during anesthesia and related critical care in the developed world during the last decade. More than 35 manufacturers offer pulse oximetry. Costs of some have fallen to less than $1500 per device, with no necessary on-going charges. Pulse oximeters are remarkable: Accuracy is +/- 2% down to 70% SaO2 without any user calibration, no drift, instantaneous readout, and almost no maintenance or safety problems. New developments include better understanding of management of premature infants, beginning use for fetal SaO2 during labor, sophisticated methods of ignoring motion artifacts and room light interference, and awareness of sources of error. Oximetry use has caused anesthesiologists and most critical care physicians to become far more able to avoid severe hypoxia in patients. Malpractice insurance rates for anesthesiologists have dropped in the USA, and other evidence suggests, although failing to prove, that anesthesia and critical care is now safer, probably due to oximetry.