Posted on 12/19/2020 9:46:40 PM PST by nickcarraway
The fingertip devices that hospitals use to monitor patients' oxygen levels might be less accurate in people with dark skin, a new study suggests.
At issue are pulse oximeters -- small medical devices that clip onto a fingertip and estimate how much oxygen is making it into the blood. They are routinely used in hospitals to help providers make treatment decisions.
And during the COVID-19 pandemic, pulse oximeters have increasingly made their way into the hands of lay people. Fairly cheap home devices are available, and people with milder cases of COVID have used them to monitor their oxygen levels.
But the new study suggests that Black patients are at greater risk of having a falsely reassuring reading on pulse oximetry than white patients are.
Researchers at the University of Michigan Hospital found that in cases where Black patients appeared to have adequate oxygen levels on pulse oximetry, their blood oxygen was actually low 12% of the time.
In contrast, the mismatch happened in white patients less than 4% of the time, the researchers report in the Dec. 17 issue of the New England Journal of Medicine.
"It really surprised us all," said lead researcher Dr. Michael Sjoding, an assistant professor of internal medicine at Michigan Medicine.
The impetus for the study was, like so many things in medicine, the pandemic.
Early on, when Sjoding and his colleagues were seeing more and more COVID patients -- many of whom were Black -- they noticed a recurring discrepancy: Some patients' pulse oximetry readings were not matching up with arterial blood gas tests, which sample patients' blood to directly gauge oxygen saturation.
To dig further, the doctors looked back at over 10,000 instances where patients had nearly simultaneous pulse oximetry and arterial blood gas measurements. The readings came from 1,333 white patients and 276 Black patients treated between January and July of this year.
Overall, the study found, discrepancies were nearly three times more common among Black patients than white patients.
Sjoding's team then looked at data from intensive care units at 178 other hospitals, collected in 2014 and 2015. The same pattern emerged: Among Black patients with normal pulse oximetry readings, arterial blood gas measurements were abnormal 17% of the time.
That compared with 6% among white patents.
The notion of a racial bias in pulse oximetry is not new. Back in 2005, a small study found that the devices tended to overestimate oxygen levels in dark-skinned patients.
But the finding did not "permeate" practice, Sjoding said, and many providers may not be aware of the issue.
Dr. Albert Rizzo is chief medical officer of the American Lung Association. He said there are various well-known limitations of pulse oximeter readings. Factors ranging from heart rate to blood circulation in the fingers to nail polish can affect measurements from the finger-clip devices.
This study, Rizzo said, "does point out that there is limited data regarding accuracy, depending on racial groups."
As for why skin tone would matter, Sjoding explained the basic theory: Pulse oximeters work by emitting certain wavelengths of light, and skin pigment may absorb some of that light.
Both he and Rizzo stressed that hospital staff need to consider factors other than pulse oximetry numbers.
"Pulse oximetry is not a stand-alone result or value," Rizzo said, "but needs to be used in the patient context."
The same goes for people using a home device to monitor a milder case of COVID.
Sjoding said that anyone with worsening breathing problems should heed those symptoms, rather than going by a seemingly "good" pulse oximetry reading.
The findings also point to a broader issue, Sjoding said. Historically, medical devices have been developed using studies of mostly white individuals. And the discrepancies seen with pulse oximetry illustrate the shortcomings of that.
"We need to double down in evaluating these technologies, to make sure they work equally well for all of the patients we treat," Sjoding said.
Now blood oxygen sensors are RACIST!
Don’t tell BLM. All they need is a new reason to march around, blocking traffic.
Actually it makes me wonder if certain races have hemoglobin that have an affinity for binding or not binding oxygen. Pulse ox actually measures the ratio of oxygenated Hgb and deoxygenated Hgb a the level of the capillary. (If memory serves its the ratio of absorption of 585 nm to 545 nm but I could be off a few mm in either Direction)
In cases of deranged Hgb such as methemoglobinenia or carboxyhemofglobinemia the pulse ox will be incorrect. Given then tendency of miscalculation it stands to reason there may be an increased amount of atypical Hgb. Wonder if sickle cell trait plays into this or other genetic variations.
It’s an interesting study.
We need someone to post the thats racist kid.
That is a very interesting theory. It would serve the medical community well, if they started ordering ABGs on those that have a higher level of skin pigmentation. Once they know definitively that their patient has an set decrease by a certain percentage point, then they can accurately adjust the oxygen level to reflect the real numbers.
And checking for sickle cell could well be a factor for that miscalculation. Just like having decrease in available O2 at a higher altitude can trigger a sickle cell crisis, it is a very reasonable probability that COVID and other breathing issues could trigger a similar crisis that goes undetected with a traditional pulse ox meter.
Anyone that invents a pulse ox that can be calibrated to allow for a more accurate ABG, would be nominated for awards. This is very similar to the PTT readings that are converted to the INR standard so that everyone is on the same page as to what their real readings are so that their Coumadin can be adjusted no matter the methodology used to perform the PTT.
By oxygen level I mean the blood oxygen level, not the supplemental oxygen that is being provided to the patient.
but no, we have to have studies designed to point out how rasist machines can be....
who is the ninkenpoop who would follow just ONE sign for a diagnosis?....
no single test for anything is absolutely perfect...
Reality is racist, apparently.
One would hope that anyone being checked in the ED for Covid or any other breathing issue is going to have a CBC done as part of the lab work. A CBC will easily diagnose anemia by the Hgb and the Hct, as well as the differential. I don’t think that a sickle cell test is routinely done unless the patient is already diagnosed with Sickle cell.
I will call one of my BFFs about this tomorrow. She is head of the Lab Hemotology Dept. for the hospital where she works. She is brilliant, and will be intrigued by this idea. She and I have had several in-depth conversation about Covid.
Govt study in 1993 noted that blacks with sickle cell disease should hormally have pulse oximetry levels below normal.
A current cdc report notes that 1 out of 365 black births have sickle cell disease and about 100,000 black Americans have sickle cell disease.
https://www.cdc.gov/ncbddd/sicklecell/data.html
You would think that testing for sickle cell would be standard procedure for people of African descent who are having a blood test anyways. Is testing for that unusually difficult or expensive? Just wondering - I’m not a doctor.
The solution is simple. Pulse oximetry device makers just need to compile in the Biden Dominion code, so blacks will get readings 120% higher than non-blacks.
Not racial bias.
Racial difference.
How about poorly controlled Type II diabetes, would that also also raise hob with a reliable reading...?
It’s possible that a simple mod of the pulse oximeters could improve accuracy.
Simply add a test for skin pigmentation....just shine an LED on the skin and read the amount of returned light and then adjust settings....should improve accuracy.
p.s. I hated drawing blood from the underside of the wrist...OUCH!
There’s no such thing as race.
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