The Food and Drug Administration (FDA) has issued a safety communication about the accuracy and limitations of pulse oximeters, given their increased use during the coronavirus disease 2019 (COVID-19) pandemic.
According to the FDA, multiple factors may affect the accuracy of pulse oximeter readings, including poor circulation, skin pigmentation, skin thickness, skin temperature, current tobacco use, and use of fingernail polish. A recent report published in the The New England Journal of Medicine has suggested that the devices may be less accurate in individuals with dark skin pigmentation. While the study had certain limitations, the authors reported that “In 2 large cohorts, Black patients had nearly 3 times the frequency of occult hypoxemia that was not detected by pulse oximetry as White patients.”
Health care providers are being advised to consider accuracy limitations when using pulse oximeters to assist in diagnosis and treatment decisions. Pulse oximeter accuracy has generally been found to be lowest at oxygen saturations below 80% and highest at saturations of 90-100%. According to the Agency, pulse oximeter readings should be used as an estimate of blood oxygen saturation (ie, a pulse oximeter saturation of 90% may represent an arterial blood saturation of 86-94%). Additionally, diagnosis and treatment decisions should be based on trends, rather than absolute thresholds.
To get a better understanding of the accuracy of a particular brand of pulse oximeter and sensor, patients and health care providers are advised to refer to the device labeling or the manufacturer’s website. Pulse oximeters are available both by prescription and for over-the-counter (OTC) use. Prescription oximeters are reviewed by the FDA and undergo clinical testing to confirm accuracy. Pulse oximeters sold OTC have not been cleared by the Agency and should therefore not be used for medical purposes.
Pulse oximeter accuracy and limitations: FDA safety communication. [press release]. Silver Springs, MD: US Food and Drug Administration; February 19, 2021.