The US Food and Drug Administration (FDA) has taken a significant step towards addressing a long-standing issue in medical technology: the inaccuracy of pulse oximeters in reading oxygen levels for individuals with darker skin tones. Pulse oximeters, small devices that clamp onto a fingertip to measure blood oxygen levels, have been a staple in medical settings and gained increased popularity during the Covid-19 pandemic. However, research spanning decades has shown that these devices can yield misleadingly high readings for people with dark skin, potentially impacting critical medical decisions.

The FDA's Draft Guidance

In an effort to enhance the reliability and reduce bias in pulse oximeters, the FDA has published draft guidance for manufacturers. This guidance includes recommendations for clinical testing and labeling of these devices. Notably, it suggests including a "diversely pigmented group of 150 or more healthy participants" in clinical studies, with at least 25% of participants in each skin color group according to the Monk Skin Tone scale. Additionally, manufacturers are advised to "prominently display appropriate warnings" in device instructions, alerting patients to the potential for differences in performance based on skin pigmentation.

Dr. Michelle Tarver, director of the FDA’s Center for Devices and Radiological Health, emphasized that this draft guidance aligns with the FDA’s commitment to facilitating the development of high-quality, safe, and effective medical devices. "Our draft recommendations are based on the best available science to help address concerns of disparate performance of pulse oximeters based on an individual’s skin pigmentation," she stated.

The Science Behind the Inaccuracy

Pulse oximeters work by sending light beams through the finger to estimate pulse rate and blood oxygen levels. A sensor detects the color of the blood—bright red indicates high oxygenation, while blue or purplish suggests lower levels. However, if not calibrated for darker skin tones, the pigmentation can affect how light is absorbed by the sensor, leading to erroneous readings. This issue has been known since the 1980s, with studies consistently showing inaccuracies in readings for Asian, Black, and Hispanic patients compared to White patients.

The Impact of Inaccurate Readings

The implications of these inaccuracies are significant. A 2022 study found that among over 3,000 hospitalized patients in intensive care, Asian, Black, and Hispanic patients received less supplemental oxygen than White patients, which was associated with differences in pulse oximeter readings. Another study revealed that Black patients had a higher likelihood of having low blood oxygen levels that were not detected by pulse oximetry, leading to a higher chance of inaccuracies. These discrepancies can result in patients not receiving necessary Covid-19 therapies or other critical care.

The FDA's Advisory Panel Meetings and Safety Communication

The FDA held advisory panel meetings in 2022 and 2024 to discuss the accuracy of pulse oximeters and ways to improve and evaluate their performance. The agency also issued a safety communication warning about the devices' limitations, particularly their reduced accuracy in individuals with dark skin pigmentation.

The Scope of the Draft Guidance

The new draft guidance applies to pulse oximeters intended for medical purposes, primarily used in hospitals and doctor’s offices, and not to devices sold as general wellness products over-the-counter. The FDA proposes creating a public webpage to identify all pulse oximeters cleared for medical purposes that have undergone review under the new guidance.

Challenges and Concerns

Despite the FDA's efforts, there are challenges to implementing these changes. The recommendations are not binding, and there is a concern that manufacturers may not fully comply. Dr. Theodore J. Iwashyna, a professor at Johns Hopkins University, noted that a similar voluntary guidance issued by the FDA in 2013 had low uptake. "Given how little compliance was seen when the last voluntary guidance was released a decade ago, we can only hope that the FDA finalizes and enforces these," he said. "Unless there is formalization, enforcement, and compliance, I am not sure why we would anticipate these ‘proposed new draft recommendations’ would result in better products, and therefore better, more equitable care."

Public health experts also worry that many over-the-counter pulse oximeters may not be included in the recommendations. However, the guidance aims to incentivize manufacturers to produce devices that perform comparably across patient groups, potentially earning a label indicating their equitable performance and inclusion on a public-facing list compiled by the FDA.

Conclusion: Towards Equitable Medical Technology

The FDA's draft guidance represents a crucial step towards addressing the bias in pulse oximeters and ensuring more equitable medical care. While challenges remain, particularly in manufacturer compliance and the inclusion of over-the-counter devices, the guidance offers a framework for improving device accuracy and transparency. It is a call to action for the medical community and manufacturers to prioritize the development of medical devices that serve all patients equally, regardless of their skin tone. As the FDA moves forward with this initiative, it is essential that these recommendations are not only finalized but also enforced to bring about tangible changes in the accuracy and reliability of pulse oximeters, ultimately enhancing patient care and safety.