CHEST Critical Care · Published 2025-09-11 · DOI 10.1016/j.chstcc.2025.100209
Background: The accuracy of blood oxygen saturation measured by pulse oximetry (Spo2) in critically ill patients with darkly pigmented skin remains controversial, with accuracy studies that are either retrospective or laboratory based among healthy volunteers. Research Question: Can a pragmatically-designed prospective study feasibly enroll critically ill patients across the full skin pigmentation spectrum within a real-world ICU setting while applying the technical rigor of a laboratory-based study? Study Design and Methods: A feasibility analysis was performed after 50 patients across 2 ICUs contributed samples. Feasibility was defined as (1) coverage of skin pigmentation, with a range of > 100° using an objective measure (individual topology angle [ITA]) and (2) ≥ 80% of collected blood samples generate a valid Spo2 and Sao2 pair fulfilling predefined technical criteria. Exploratory analysis was performed through Bland-Altman analysis, with standard-of-care blood draws used for Sao2 measurements. Rates of occult hypoxemia (Sao2 < 88% when Spo2 was 92%-96%) were compared among skin pigmentation groups. Results: Eighty-four blood samples collected from 50 patients (52% male; median age, 55 years [interquartile range, 46-61.8 years]) yielded 80 valid pairs (95%) from 49 patients. Feasibility thresholds were met for skin pigmentation (ITA range, –66° to 59°), with 52% of patients classified as dark-skinned overall. In the exploratory analysis, overall pulse oximeter root-mean-square accuracy was 1.47%, with a median bias of –0.6% (mean, –0.7%). Dark-skinned and light-skinned patients did not differ significantly, with a median bias of –0.2% vs –0.9% (mean, –0.1% vs –1.1%), respectively. Nearly one-half the data pairs were collected when patients were at risk of occult hypoxemia (Spo2, 92%-96%), yet no occult hypoxemic events occurred. Interpretation: This feasibility study demonstrated high fidelity and efficient data collection from pulse oximeter sensors and reference blood gas analyzers in critically ill patients across varying skin pigments while applying requisite technical criteria within an ICU setting. Clinical Trial Registration: ClinicalTrials.gov; No.: NCT06432881; URL: www.clinicaltrials.gov
Abstract from DOAJ. Public domain (CC0 1.0).
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