Are oxygen desaturations that only last for a few seconds significant?
Probably not. Pulse oximeters display an oxygen saturation that is an average over a period of time. The technology was first developed for intraoperative monitoring, when beat-to-beat saturation readings are desirable, not for use in EDs and offices to predict respiratory deterioration. Most instruments are programmed with short averaging times, typically 3 to 5 seconds. A longer averaging time will not detect brief episodes of hypoxemia but will display a number that better represents the general trend in oxygen saturation. A brief period of desaturation identified by a pulse oximeter with a short averaging time may signify a very transient physiologic event that does not reflect the general status of pulmonary function. Although controversial, most authorities do not believe brief episodes of mild desaturation lead to significant morbidity.