Skin Pigmentation and Pulse Oximeter Accuracy in the Intensive Care Unit: a Pilot Prospective Study

Abstract

AbstractRationaleDespite multiple reports of pulse oximeter inaccuracy among hospitalized Black individuals, regulatory testing of pulse oximeters is performed on healthy volunteers.ObjectiveEvaluate pulse oximeter accuracy among intensive care unit patients with diverse skin pigmentation.MethodsSkin 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-SaO2with skin pigmentation.Measurements and Main ResultsSampling 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% ARMScompared to 0.34% bias and 1.97% ARMSamong lighter pigmented individuals. After adjusting for SaO2, pH, heart rate, and mean arterial pressure, SpO2-SaO2was falsely elevated by 1.00% more among darkly pigmented individuals (95% confidence interval: 0.25-1.76%). SpO2significantly overestimated SaO2for dark, brown, and tan forehead or forearm pigmentation and brown and tan finger pad pigmentation compared to intermediate/light pigmentation.ConclusionsThe 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.