Sentence:  The pulse <WSD>oximeter</WSD> (SpO2) is a fast growing and commonly utilized transcutaneous methodology that represents a combination of oximetry and plethysmographic technologies for screening, treatment planning and evaluation and research [...] Precision of various pulse <WSD>oximeters</WSD> were noted [to] be fairly consistent at approximately 2% [...]. 
Meaning of the word marked with <WSD> tags:  A device that measures the oxygen saturation of arterial blood. (from 1942)<ref name="Brans & Hay"/>