Do Differences in Skin Pigmentation Affect Detection of Hypoxemia by Pulse Oximetry: A Systematic Review of the Literature.
Shannon A Cotton, Jung-Ah Lee, Atul Malhotra and 1 others
PMID 41045137WHAT IT FOUND
Pulse oximeters often overestimate oxygen saturation in people with darker skin, leading to missed hypoxemia.
While average bias is small, accuracy drops as true saturation falls, and device-specific errors persist. Clinicians must interpret SpO2 alongside clinical signs, not in isolation.
Key findings
01Pulse oximeters consistently overestimate arterial oxygen saturation in individuals with darker skin pigmentation, creating a risk of occult hypoxemia where true oxygen levels are dangerously low but readings appear normal.
02The magnitude of bias varies significantly by device manufacturer and model, with some devices failing to meet FDA accuracy standards specifically in darker-skinned individuals.
03Accuracy is generally acceptable when oxygen saturation is high, but bias increases and becomes clinically significant as true arterial saturation decreases.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
Many included studies relied on subjective or self-reported race and ethnicity rather than objective measures of skin pigmentation like spectrophotometry. A significant portion of the data came from retrospective studies or laboratory settings with healthy volunteers, which may not fully reflect the complexities of hospitalized patients with poor perfusion. Few prospective studies directly linked these measurement discrepancies to patient outcomes, so the clinical impact of occult hypoxemia is inferred rather than proven by this review.
Declared interests
Dr. Malhotra reports funding from NIH and income from Livanova.
The easy way to misread this
Do not assume that a normal SpO2 reading rules out hypoxemia in patients with darker skin tones. The bias is small on average but can be significant in individual patients, particularly when true oxygen saturation is already low.