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Comment by Edmond | Hacker News Reader

The article notes that the devices inaccurately report higher oxygen levels for darker skin tones. Meaning if someone dark skinned reports a result that falls into the 94-100% range, they may in fact be at lower oxygen levels that put them at risk.

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The bias is smaller than the actual measurement error. The measurement error is around +/- 1. So a 96 reading means actual blood O2 of 95-97. The bias introduced by skin color is around 0.5. So a 96 reading means 95-97 in a white person and 94.5-96.5 in a black person. The bias from skin color isn't significant because the measurement itself is pretty inaccurate.

That's true. There are other context clues that we can use, like a patient's medical history, how their breathing looks/sounds, or if their environment or mental status suggests CO poisoning (that also won't show up even on the perfect pulse ox, since it binds to hemoglobin the same way oxygen does). Overall we just need a better way to get information about oxygen levels.

At first thought, a hemoglobin protein loaded up with CO molecules should have slightly less mass than an oxygenated hemoglobin complex, which could... theoretically... be measured, maybe with Raman spectroscopy.

That effect is going to be tiny, though. Wikipedia is telling me a hemoglobin tetramer masses "about" 64,000 daltons, so a complex loaded up with 4CO will mass 64,111 vs 64,127 amu. 0.024% difference.

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