A new study published in the New England Journal of Medicine says that the results of a pulse oximeter three times are likely to give misleading results in patients with black skin.

A pulse oximeter is a small device attached to the thumb that tells health workers about a person’s level of blood oxygenation. A pulse oximeter works by a process that recognizes the level of oxygen in the blood by passing light through the skin. It is thought that the wrong result on black skin could be because the darker skin pigments absorb light differently.

The COVID-19 pandemic has led to an increase in the use of the device. It helps to know patients who are in critical conditions and who could benefit from the use of oxygen, or in making a decision to transfer a patient to intensive care units. Those who isolate themselves at home can also use this to monitor their own condition to know if they need to go to the hospital urgently.

Interestingly, this is not the first time this has been reported. A few years ago, research raised this problem, but it was not taken seriously. But this latest research in a pandemic is changing everything.

Some also say the report underscores racial discrimination in medical practice, especially for a disease pandemic that has killed more blacks and Latinos than whites in America.

Dr Michael W. Sjoding, an assistant professor of internal medicine at the University of Michigan School of Medicine and lead author of the new report, said: “I think most of the medical community operates on the assumption that pulse oximetry is fairly accurate. He added, “I’m a trained pulmonologist and critical care physician and I had no understanding that the pulse ox was potentially inaccurate – and that I lack hypoxemia in a certain minority of patients.”

The research analyzed the results of the pulse oximeter and compared them with the results of measuring arterial gases, which is a more invasive test. Arterial blood gas requires blood sampling and this test is rarely done today.

The results of 10,789 paired tests of 1,333 white and 276 black patients hospitalized at the University of Michigan showed that pulse oximetry “overestimated oxygen levels by 3.6 percent of the time in white patients, but misunderstood it in nearly 12 percent of cases or more than three times. more often, in blacks. “

The pulse oximeter erroneously gave oxygen levels for these patients between 92 and 96 percent, when it was indeed low up to 88 percent. Oxygen levels are said to be less than 95 abnormal.

The researchers also analyzed a multi-hospital database comparing 37,308 matched tests of ICU patients hospitalized in 178 medical centers in 2014 and 2015, and found the same discrepancies.


There are suggestions that pulse vol could be improved with a setting that adjusts a different calibration for darker pigmented skin. It is also suggested that the device carries a warning label that allows users to be aware of the possibility that the device may overestimate oxygen levels in blacks.

While we hope that local studies can be done to see if the same results are seen in Nigeria, it is a wake-up call for healthcare professionals in Nigeria to examine patients holistically and individually, rather than relying too heavily on a device that can spoil itself.

Dr. Cosmas Odoemena, a physician from Lagos