Design of a Skin-Tone Inclusive Technique for the Non-Invasive, Transcutaneous Measurement of Bilirubin

Trujillo, Eddy, School of Engineering and Applied Science, University of Virginia
Guilford, William, EN-Biomed Engr Dept, University of Virginia

The technical work I performed while developing a skin-tone inclusive technique for the non-invasive measurement of bilirubin is closely related—both technically and in its social implications—to my STS research project, where I explored how the overestimation of oxygen saturation by pulse oximeters defined power relations between Black and White patients during the COVID-19 pandemic. Technically, the projects relate in that the primary contributor to their respective shortcomings is largely attributable to melanin—a chromophore in the skin that not only has a particularly wide light absorption spectrum, but is also found in higher concentrations in patients with darker skin tones. The technologies described in both projects have a tendency to marginalize Black patients by reducing their likelihood of receiving quality clinical care. This directly increases mortality rates and reinforces existing race-related socioeconomic disparities by increasing medical care costs for an already vulnerable and largely uninsured population.
Neonatal jaundice is a common condition caused by a build-up of bilirubin—a byproduct of hemoglobin destruction—in the blood. Currently, bilirubin levels in neonates of darker skin tones are frequently overestimated by bilirubinometers, making the predictive utility of this light absorption-based screening method lower in racial populations with higher melanin contents. This is due to the high degree of overlap between the absorption spectra of bilirubin and melanin, which makes it difficult to determine whether variations in the reflectance spectra collected by bilirubinometers are attributable to bilirubin specifically. This issue is addressed by using blue light to stimulate a photoisomerization reaction that converts bilirubin to a colorless substance. My team aims to prove that collecting absorption spectra both before, during, and after locally photobleaching the bilirubin in a small patch of skin makes it possible to distinguish the degree of absorption that occurs specifically due to bilirubin by generating a complete decay curve.
My STS research addresses a similar issue, but focuses on the opposite end of the spectrum; it analyzes the implications of the instillation of racial bias into pulse oximeters beyond the narrow scope of clinical care. Current infrared thermometers have a strong tendency to overestimate blood oxygen saturation levels in patients with higher melanin concentrations, and darker-skinned minority patients’ resultant 23-29% decreased likelihood of recognition for COVID-19 therapy eligibility relative to Whites played a powerful role in defining power relations between racial groups during the pandemic. My writing corroborates evidence to argue that the overestimation of blood oxygen saturation levels during the COVID-19 pandemic played a notable role in defining mortality rates, perpetuating racially-biased healthcare spending, and ultimately marginalizing minority patients using the framework of technological politics developed by Langdon Winner.
The value of addressing these technical and social problems conjunctively lies in the consequences that would arise if I focused on only one. Without consideration of the technical shortcomings that make bilirubinometers and infrared pulse oximeters melanin-dependent, the racial bias in these technologies would persist. My technical work also provided a strong context and background for my understanding of how melanin contributes to the overestimation of oxygen saturation levels in Black patients. Additionally, if the role of pulse oximeters in defining power relations between racial groups were ignored, the issues evident in current technology would remain unacknowledged and the pressure engineers feel to be cognizant of bias in the design of future devices may remain low—leading to the reproduction of unfair devices whose technical shortcomings perpetuate inequality. My STS research informed me of the consequences that would result if the technical issues present in bilirubinometers went unaddressed.

BS (Bachelor of Science)
bilirubin, bilirubinometer, phototherapy, photobleach, pulse oximeter
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