Pulse Oximetry

October 27, 2020 | Healthcare Risk, Quality, & Safety Guidance

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​​​Pulse oximetry monitoring is a standard of care across many medical settings—in the operating room, postanesthesia care unit, intensive care unit (ICU), or neonatal ICU; during emergency medical transport and emergency department examination; and even on general medical floors or in outpatient clinics. This noninvasive measurement also offers convenient and fast results in sleep laboratories, home-based healthcare, and assisted-living facilities. Pulse oximetry demonstrated special value in managing the coronavirus disease (COVID-19) pandemic; decreasing oxygen saturation is often an early warning sign of infection in otherwise largely asymptomatic or mild presentations.

Pulse oximetry has several benefits, including the ability to noninvasively measure blood saturation. Measurements can be taken continuously for long-term monitoring or intermittently for spot checks. Deterioration of the patient's condition is quickly evident, and response to therapy—specifically, oxygen therapy—can be measured rapidly (Booker).

Pulse oximeters display oxygen saturation (SpO2) and pulse rate. Some oximeters will display a plethysmogram, a waveform representing the strength and shape of the pulse oximetry signal.

SpO2 readings are displayed as a percentage; measurements can fall between 70% and 100%. Patient measurements typically range from 95% to 100%, but the most common reading on a normal patient is 97% (Booker). SpO2 and oxygen saturation measured via arterial blood gas (SaO2), an invasive but more direct measurement, can deviate somewhat from each other, but they should be relatively close (Zeserson et al.). If the oxygen saturation reading taken from a pulse oximeter and that from arterial blood gas analysis differ by more than 5%, the patient's hemoglobin level is likely abnormal (Akhtar et al.).

Pulse oximetry serves as a more immediate and more convenient alternative to an invasive arterial blood gas measurement, although there are circumstances that can invalidate pulse oximetry findings (see the discussion Ensure Proper Function and Use of the Pulse Oximeter​). Therefore, arterial blood gas is still the definitive measurement...

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