The analysis, of 10,789 paired test results from 1,333 white and 276 black patients hospitalized at the University of Michigan earlier this year, found that pulse oximetry overestimated oxygen levels 3.6% of the time in white patients, but got it wrong almost 12% of the time, or more than three times as often, in black patients.
In these patients, pulse oximeter measurements incorrectly indicated that the oxygen saturation level was between 92% and 96%, when in fact it was as low as 88% (results were adjusted for depending on age, gender and cardiovascular disease).
The coronavirus epidemic>
Words to know about testing
Confused by the terms relating to coronavirus testing? Let us help you:
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- Antibody: A protein produced by the immune system that can recognize and attach precisely to specific types of viruses, bacteria or other invaders.
- Antibody test / serological test: A test that detects specific antibodies to the coronavirus. Antibodies start to appear in the blood about a week after the coronavirus has infected the body. Because antibodies take so long to develop, an antibody test cannot reliably diagnose an ongoing infection. But it can identify people who have been exposed to the coronavirus in the past.
- Antigen test: This test detects pieces of coronavirus protein called antigens. Antigen tests are quick, take only five minutes, but are less accurate than tests that detect the genetic material of the virus.
- Coronavirus: Any virus belonging to the Orthocoronavirinae family of viruses. The coronavirus that causes Covid-19 is known as SARS-CoV-2.
- Covid19: The disease caused by the new coronavirus. The name is the abbreviation for coronavirus disease 2019.
- Isolation and quarantine: Isolation is the separation of people who know they have a contagious disease from those who do not. Quarantine refers to restricting the movement of people who have been exposed to a virus.
- Nasopharyngeal swab: A long, flexible stick with a soft swab that is inserted deep into the nose to take samples from the space where the nasal cavity meets the throat. Samples for coronavirus tests can also be collected with swabs that do not penetrate as deep into the nose – sometimes called nasal swabs – or oral or throat swabs.
- Polymerase chain reaction (PCR): Scientists use PCR to make millions of copies of genetic material in a sample. Tests using PCR allow researchers to detect the coronavirus even when it is rare.
- Viral load: The amount of virus in a person’s body. In people infected with the coronavirus, the viral load may peak before starting to show symptoms, if symptoms do appear.
Oxygen levels below 95 percent are considered abnormal, so “a small difference in the pulse oximetry value within this 92 to 96 percent range could be the difference in deciding whether the patient is really sick or not. really sick, or need different treatment or not, ”Dr Sjoding said.
Another analysis of the study looked at a multi-hospital database to compare 37,308 similar matched test results from critical care patients who had been hospitalized at 178 medical centers in 2014 and 2015. This analysis, which did not was not adjusted, found similar deviations.
Dr Sjoding said he and his colleagues embarked on the study after hospitals in Ann Arbor, Mich., Which typically treat a predominantly white patient population, received a large influx of patients with Gravely ill Coviders from Detroit, many of whom were African American. “We started to see deviations with the arterial blood gases, and we didn’t know what to think about it,” he said.
He remembers reading an article in The Boston Review in August about racial disparities in the accuracy of pulse oximeter readings. The author of this article, Amy Moran-Thomas, became interested in the device after buying one when her husband was sick with Covid. She unearthed scientific papers published as early as 2005 and 2007 that reported inaccuracies in pulse oximeter readings in dark-skinned individuals at low levels of oxygen saturation.
Dr Sjoding and his colleagues decided to conduct a study using data that had already been collected during routine hospital care at the hospital. “What we were seeing anecdotally was exactly what we ended up showing in the last article, that on the monitor in the patient’s room the pulse oximeter read ‘normal’, but when we got blood gas arterial saturation on the gas was low, ”he says.
