Pulse Oximeters May Fail People of Color: What You Need to Know

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We investigate how pulse oximeters – those small devices that clip onto your finger and measure oxygen levels – can show bias against people with darker skin tones. This critical medical tool may overestimate oxygen readings in Black patients, potentially leading to delayed or inadequate treatment.

• Pulse oximeters use infrared light to measure blood oxygen, but melanin in darker skin can scatter this light and cause inaccurate readings
• Studies show Black patients are nearly three times more likely to have hidden low oxygen episodes missed by pulse oximeters
• During COVID-19, this bias became particularly dangerous as oxygen readings determined critical treatment decisions
• Most pulse oximeters were originally calibrated on light-skinned individuals, with minimal diversity requirements
• The FDA is now developing better standards requiring more diverse testing groups
• This issue extends beyond pulse oximeters and reveals broader systemic healthcare inequities
• Medical practitioners need to consider the whole clinical picture rather than relying solely on pulse ox readings

Stay healthy, my friends, until next time.

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Production and Content: Edward Delesky, MD & Nicole Aruffo, RN
Artwork: Olivia Pawlowski

Episode Transcript

Speaker 1 (00:04):
Hi, welcome to your checkup.
We are the patient educationpodcast, where we bring
conversations from the doctor'soffice to your ears.
On this podcast, we try tobring medicine closer to its
patients.
I'm Ed Dolesky, a familymedicine doctor in the
Philadelphia area.

Speaker 2 (00:19):
And I'm Nicole Rufo.
I'm a nurse.

Speaker 1 (00:20):
And we are so excited you were able to join us here
again today on what is a veryspecial, important episode,
where we are going to talk aboutsomething that involves many of
us patients, even cliniciansand, honestly, it's been trusted
for decades and it's called thepulse oximeter.

(00:40):
It's the little device thatclips to your finger and tells
you your oxygen level, andsomething that is coming to
light and that's been known fora while this article came out in
June of 2024, and we'rereviewing it this year, one year
later is that the pulseoximeter may not tell the same
story for everyone, and so it'ssomething important that we're

(01:03):
talking about today, and oneimportant question we're asking
is can a device be biased?
And the answer, seeminglyshockingly, is yes, and so today
we're going to talk about howpulse oximeters may overestimate
oxygen levels in people withdarker skin tones and what that

(01:24):
means for the health of for youor your neighbor or a loved one,
and the health care system as awhole.
So, nikki, can you tell us whatis a pulse oximeter?

Speaker 2 (01:37):
So a pulse oximeter, or otherwise known as a pulse ox
, which you may have heard, is asmall device, usually a clip,
where it can be a little stickerthat goes around your finger.
You can put it on a toe, anearlobe, but it shines.
It has that red light, that'san infrared light that shines
through your skin and itmeasures how much oxygen is in

(01:59):
your blood.
It's a critical tool inhospitals and doctor's offices,
even at home.
I mean you can like buy them onamazon or get it at a pharmacy
and people can use them daily tomonitor their oxygen levels and
it's a pretty like.

Speaker 1 (02:16):
I mean people like depend on them for valuable
information right, because Imean, like this is, it's a vital
sign and important clinicaldecisions are made.
I mean, I was in the office twoweeks ago and I was thinking,
based on this number, I'm goingto decide whether this person
goes to the hospital or not.

(02:37):
Yeah, those types of decisionsare made every day with the
pulse ox.
Or is this person who is in thehospital ready to go home?
Does this person need oxygen athome and completely reshape
their lifestyle?
And so this article that we'rereviewing today kind of
indicated that there is ahistory of inaccuracy, and they

(02:57):
highlight several stories.
The first red flag about biasin these devices came about 30
years ago, and back in 1990,researchers found that pulse
oximeters tended to overestimateoxygen levels in black patients
compared to white patients, andthat means that device might
say oxygen level is fine whenactually it's too low.

(03:21):
Despite follow-up studies inthe early 2000s, these warnings
didn't get much attention andwhat really happened is that it
took COVID to actually reallyput this into notice.

Speaker 2 (03:35):
So during COVID, which you may remember, you may
remember oxygen, accurate oxygenreadings were pretty much
everything and critical.
Like you were just explaininghow that could determine if
someone went to the hospital, ormaybe if they were in the
hospital or if someone wasintubated during their admission

(03:58):
.
Um, but the university ofMichigan did a pretty big study
in 2020 where they discoveredthat black patients were nearly
three times more likely to havethese hidden episodes of low
oxygen, even if their pulse oxwas reading like it was normal.
Um, so that means that theywere three times more likely to

(04:22):
have a low oxygen missed.

Speaker 1 (04:25):
That's a lot.

Speaker 2 (04:26):
And so, because of that, someone was either not
getting the supplemental oxygenthat they needed, or maybe they
were admitted to the hospitallater, when they were a little
bit more compromised and moresick, which those delays could
be life-threatening andunfortunately probably were.

Speaker 1 (04:46):
Yeah, and so one big question is why does this happen
?
And so pulse oximeters work bysending light through the skin,
but melanin, the pigment thatmakes skin darker, can absorb or
scatter that light, and so thedevices were originally
calibrated decades ago, oftentested mostly or completely

(05:10):
entirely on people with lighterskin, and even today, some
devices are approved withoutclear evidence that they work
across different skin tones, andso there was another recent
investigation that found 25% ofpulse oximeters approved after
2016 didn't mention skin tonetesting at all, and the FDA,
until recently, their guidanceonly suggested testing on two

(05:33):
dark-skinned individuals or 15%of a study group.
It wasn't required orstandardized, and so this
technology was really set up forblind spots, like literally.
And so what is being done aboutany of this?
Because this is massivelyimportant.

Speaker 2 (05:53):
So the good news is that, since 2020, the FDA has
prioritized this issue andthey've been working with
scientists and these devicecompanies to develop better
standards, with newer guidelinesexpected to require a more
diverse group of test subjects.
I don't know why they didn't dothis 30 years ago, but that's

(06:16):
probably a whole another wholediscussion.
Yeah literally Discussion Racism, yeah, literally.
Engineers are also working onsmarter technology, such as a
dual ratio, optical systems thatmay adjust readings based on
individual tissue differences,but not quite ready for
widespread clinical use yet.

(06:37):
Not prime time, mm-mm.
So, unfortunately, until all ofthese new rules are in place
and new devices are on themarket, this is where we are.

Speaker 1 (06:50):
Yeah, and still using the old technology that was
known to be flawed, that studywhere it was three times more
likely.
They found that in whitepatients, the discordance
between an arterial blood gasand the pulse ox was 4% in white
individuals and 12% in blackindividuals, to put that number

(07:11):
into a little bit more context.
And so where does it leave us?
That's a tough question.
I know we have a lot ofpatients here listening and it's
something to just keep in mindwhen you're advocating for
yourself.
We don't rely on one number.
You look at the whole clinicalpicture as one thing, as a
doctor and whoever's taking careof patients, and this really

(07:35):
just calls into light that weneed to be more aware of bias in
medicine.
This calls into a much biggerpicture that bias in medicine
doesn't limit itself to medicaldevices.
It's not just a technical flaw.
This was done because of bias.
All of the testing was done onwhite patients in the beginning

(07:56):
because of bias, and this is asystemic equity issue.
For those listening who mightnot understand what equity
versus equality is equalitybeing the thought that everyone
gets the same thing and equitybeing the thing that everyone
gets what they individually needto raise them up, and so it's

(08:17):
Really a reminder that what'sstandard quote unquote in
medicine often has left outpeople of color.
And fixing it isn't just aboutupdating technology, it's about
updating how we think and how wedesign and how we regulate our
entire healthcare system.
And the pulse ox is just alittle, very tiny, tiny tip of
the iceberg about what is a muchdeeper, widespread issue.

(08:40):
I mean, this came up, this isin calculators, this is in the
ASCVD, the cardiovascular riskscore, where there is a toggle
for whether someone isAfrican-American or not in the
score.
Or another one I can thinkabout is kidney function.

Speaker 2 (09:04):
One I can think about is kidney function, old kidney
scores for egfr, which is theamount of flow that, like
measured going through yourkidney included whether you were
african-american or not, andthis is so now I'm thinking of
because there have been a fewtimes where we had like a rapid
on a kid and like their bloodgas came back and like the

(09:24):
oxygen level was different thanthe monitor.

Speaker 1 (09:28):
Yeah.

Speaker 2 (09:28):
Which, honestly, like a pulse ox, isn't perfect
regardless of what color skinyou have, especially on a kid,
Like if you wiggle your tail.
It's like you know crazy.
But yeah.
Yeah, cause, like, yeah, likecrazy.
But yeah, yeah, cause, like,yeah, like the blog guys will
come back.
I'm like, oh, that makes sensewhy you look so punky.

(09:50):
Yeah, even though you're youknow the monitor was reading
your.
It was like 95 or whatever.

Speaker 1 (09:57):
It's, it's everywhere .
I mean, like reading this, itmakes me roll back and call into
question of, like tons ofsituations.
It's a lot and it's importantand so now, if you're listening
to this, you could be mindfulfor yourself, a loved one or a
neighbor.
I kind of stole your thunderthere for a second.

Speaker 2 (10:19):
Yeah, you did.
It's okay, I'll let you have it.

Speaker 1 (10:21):
Thank you for coming back to another episode of your
Checkup.
Hopefully today you were ableto learn something for yourself,
a loved one or a neighbor.
Find us on our website to findour old episodes.
Follow the podcast so that youcan get updates about when
future episodes come out.
You can find us on Instagram.
We're very active on threads,if you like text-based social

(10:41):
media.
Still, it's what Twitterbasically used to be.
Most importantly, stay healthy,my friends, until next time.
I'm Ed Dolesky.
I'm Nicola Ruffo.
Thank you and goodbye, bye, bye.
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(11:14):
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(11:37):
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