Rationale: Despite multiple reports of pulse oximeter inaccuracy among hospitalized Black individuals, regulatory testing of pulse oximeters is performed on healthy volunteers. Objective: Evaluate pulse oximeter accuracy among intensive care unit patients with diverse skin pigmentation. Methods: Skin pigmentation was measured using a chromameter in 12 patients and individual typology angle (ITA), a measure of constitutive pigmentation, calculated. Arterial blood gas (ABG) arterial oxygen saturation (SaO2) sampling was precisely matched to pulse oximetry (SpO2) using arterial line waveforms analysis. Error (SpO2-SaO2), bias, and average root mean square error (ARMS) were calculated. Multivariable linear mixed effects models evaluated the association of SpO2-SaO2 with skin pigmentation. Measurements and Main Results: Sampling time was determined for 350 ABGs. Five participants (N=96 ABGs) were darkly pigmented (forehead ITA<-30°), and 7 lighter pigmented (N=254 ABGs). Darkly pigmented individuals had 1.05% bias and 4.15% ARMS compared to 0.34% bias and 1.97% ARMS among lighter pigmented individuals. After adjusting for SaO2, pH, heart rate, and mean arterial pressure, SpO2-SaO2 was falsely elevated by 1.00% more among darkly pigmented individuals (95% confidence interval: 0.25-1.76%). SpO2 significantly overestimated SaO2 for dark, brown, and tan forehead or forearm pigmentation and brown and tan finger pad pigmentation compared to intermediate/light pigmentation. Conclusions: The pulse oximeter in clinical use at an academic medical center performed worse in darkly pigmented critically ill patients than established criteria for FDA clearance. Pulse oximeter testing in ICU settings is feasible, and could be required by regulators to ensure equivalent device performance by skin pigmentation among patients.

The authors have declared no competing interest.

This work was supported by funding from John Hopkins inHealth (the Johns Hopkins Precision Medicine initiative) and the John Templeton Foundation. AF is supported by NIH National Heart, Lung, and Blood Institute (NHLBI) grant K23HL151758.

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