Background The International Organization for Standardization (ISO) and US Food and Drug Administration (FDA) are updating standards and guidance for pulse oximeters to reduce performance disparities linked to skin pigment. We tested common oximeters with current and anticipated regulatory frameworks. We hypothesized that most oximeters would show more positive bias in darkly vs lightly pigmented participants and that fewer oximeters would ‘pass’ anticipated regulations.

Methods We used a controlled desaturation protocol to test 34 oximeters across arterial oxygen saturations (SaO2) 70–100% in healthy adults. Based on what FDA and ISO had shared at the time of study design, we studied cohort sizes of > 24 with > 25% of participants being darkly pigmented. We used the subjective Monk Skin Tone (MST) scale and the objective individual typology angle (ITA) derived from a spectrophotometer to characterize skin pigment. The root mean square error (ARMS), bias (mean of SpO2 - SaO2 error), and skin pigment differential bias were calculated. Monte Carlo simulation explored potential impacts of participant selection on device passing.

Results For cohorts of 24 participants, 28/34 oximeters passed 2017 ISO Standard ARMS < 4%, 22/34 passed 2013 FDA guidance ARMS < 3%, 21/34 oximeters passed both ARMS and differential bias criteria for anticipated ISO standards, and 1/34 passed anticipated FDA criteria. More devices passed with cohorts > 24. Eleven oximeters had more positive bias in participants with dark vs. light (dorsal finger) pigmentation across 70– 100% SaO2. Eighteen devices could pass or fail depending on cohorts selected for analysis.

Conclusions Pulse oximeters show variable performance across manufacturers and models, with only some devices showing more positive bias in people with darker skin. Anticipated updates to ISO and FDA frameworks yield strikingly different assessments and require refinement. Whether they will translate into improved real-world performance or reduced health disparities is yet to be determined.

The authors have declared no competing interest.

https://openoximetry.org/study-protocols/

This study was conducted as part of the Open Oximetry Project funded by the Gordon and Betty Moore Foundation, Patrick J McGovern Foundation, PATH/UNITAID, and Robert Wood Johnson Foundation. Dr. Ellis Monk's time utilized for data analysis, reviewing, and editing was funded by grant number DP2MH132941.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

IRB of the University of California, San Francisco gave ethical approval for this work

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes