Pulse oximetry is a widely used, noninvasive method for estimating arterial oxygen saturation (SaO2). However, emerging evidence suggests that skin pigmentation may affect its accuracy, potentially leading to occult hypoxemia in individuals with darker skin tones. This systematic review examines the impact of skin pigmentation on pulse oximeter accuracy by comparing pulse oximetry (SpO2) readings with arterial blood gas-measured SaO2 across diverse populations. A systematic search of PubMed and Embase was conducted following PRISMA 2020 guidelines. Eligible studies included those comparing SpO2 to SaO2 while stratifying results by skin pigmentation or race/ethnicity. Data extraction focused on bias in SpO2 readings, study design, and population characteristics. Risk of bias was assessed using the QUADAS-2 tool. Forty-two studies met the inclusion criteria. Consistent evidence indicated that pulse oximeters overestimate SaO2 in individuals with darker skin tones, particularly at lower oxygen saturations. This overestimation may delay recognition of hypoxemia and critical interventions. Methodological variability was noted, including inconsistent racial classifications and skin tone assessment methods. Pulse oximeters exhibit a systematic bias in individuals with darker skin tones. Standardized skin pigmentation assessment and improved device calibration are needed to enhance accuracy and ensure equitable patient care.
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