Racial Disparities in Pulse Oximeter Device Inaccuracy and Estimated Clinical Impact on COVID-19 Treatment Course

Abstract

Arterial blood oxygen saturation measured by pulse oximetry (SpO2) may be differentially less accurate for people with darker skin pigmentation, which could potentially affect COVID-19 treatment course. We analyzed pulse oximeter accuracy and association with COVID-19 treatment outcomes using electronic health record (EHR) data from Sutter Health, a large, mixed-payer, integrated healthcare delivery system in northern California, United States (US). We analyzed two cohorts: (1) 43,753 concurrent arterial blood gas (ABG) oxygen saturation (SaO2)/SpO2 measurement pairs taken January 2020-February 2021 for Non-Hispanic white (NHW) or Non-Hispanic Black/African American (NHB) adults, and (2) 8,735 adults who went to the emergency department (ED) with COVID-19 July 2020-February 2021. Pulse oximetry systematically overestimated blood oxygenation by 1% more in NHB individuals than in NHW individuals. For people with COVID-19, this was associated with lower admission probability (-3.1 percentage-points), dexamethasone treatment (-3.1 percentage-points), and supplemental oxygen treatment (-4.5 percentage-points), as well as increased time-to-treatment: +37.2 minutes before dexamethasone initiation and +278.5 minutes before initiation of supplemental oxygen. These results call for additional investigation of pulse oximeters, and suggest that current guidelines for development, testing, and calibration of these devices should be revisited, investigated, and revised.

Variations of skin thermal diffusivity on different skin regions

“…The high light absorption and scattering capacity of melanin ensures that harmful UV radiation is either scattered or absorbed in the uppermost layer of the skin and therefore protects the underlaying layers from DNA photodamage 45 . Such a behavior leads to inaccuracies in optical measurements for dark skin people 46,47 due to the high absorption characteristics of melanin as well as the fact that cosmetic procedures such as hair follicle removal or port wine stain treatment are not as effective for all phenotypes 48,49 . As hypothesized in the study by Charlton et al., radiative properties of human skin may not be affected by melanin 50 .…”

Discrimination by Design: Is It Time to Recalibrate Interpretation of Pulse Oximetry?*

“…In contrast, only one pediatric publication observed no statistical difference in accuracy by skin pigmentation (25). While limited data evaluates clinical implications of occult hypoxemia in children, all published adult studies observed associations with adverse outcomes, including receipt of less supplemental oxygen, delayed COVID-19 therapies or ICU transfer, and higher organ dysfunction as well as mortality (22,(26)(27)(28)(29)(30).…”

Using Technology to Detect Erythema Across Skin Tones

“…The documented inaccuracy of pulse oximetry among individuals with dark skin tones has been a known issue for over 20 years. Moreover, the profound treatment inequities experienced by individuals with dark skin tones stemming from the limitations of pulse oximetry were particularly evident during the COVID-19 pandemic 16,17 . The underdetection of hypoxemia with pulse oximeters in persons with dark skin tones led to differences in treatment decisions including administration of supplemental oxygen, intravenous dexamethasone, and hospital admission 17 …”

“…Moreover, the profound treatment inequities experienced by individuals with dark skin tones stemming from the limitations of pulse oximetry were particularly evident during the COVID-19 pandemic. 16,17 The underdetection of hypoxemia with pulse oximeters in persons with dark skin tones led to differences in treatment decisions including administration of supplemental oxygen, intravenous dexamethasone, and hospital admission. 17 Melanin absorbs and scatters light at specific wavelengths used in the measurement process, which necessitates its consideration in measurement algorithms.…”

“…16,17 The underdetection of hypoxemia with pulse oximeters in persons with dark skin tones led to differences in treatment decisions including administration of supplemental oxygen, intravenous dexamethasone, and hospital admission. 17 Melanin absorbs and scatters light at specific wavelengths used in the measurement process, which necessitates its consideration in measurement algorithms. Further, the accuracy of measurements can vary depending on the body region.…”