pulse oximetry

Pulse oximetry is a noninvasive method for monitoring a person's oxygen saturation (SO₂). Its reading of SpO₂ (peripheral oxygen saturation) is not always identical to the reading of SaO₂ (arterial oxygen saturation) from arterial blood gas analysis, but the two are reliably enough correlated that the safe, convenient, noninvasive, inexpensive pulse oximetry method is valuable for measuring oxygen saturation in clinical use.