pulse oximetry

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pulse oximetry (oks-im-it-ri) n. a technique for measuring the percentage of haemoglobin in arterial blood that is saturated with oxygen. Utilizing the fact that haemoglobin is photosensitive, it enables changes in oxygen levels to be rapidly detected. The equipment used (a pulse oximeter) incorporates a light-emitting sensor and photodetector placed on a finger, foot, or ear lobe; sites should be changed every 4 hours to prevent pressure necrosis. Saturation levels of less than 90% are a cause for concern.