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When Pulse Oximeter Readings Change October 6, 2026 · 2:37 · With Grace
A five-year study at Johns Hopkins Hospital found that the pulse oximeters it examined shifted from overestimating blood oxygen to underestimating it.
Transcript Grace You’re listening to Slow English FM. I’m Grace, and this is a health chronicle about changing pulse oximeter readings. Grace A five-year study at Johns Hopkins Hospital found that the pulse oximeters it examined shifted from overestimating blood oxygen to underestimating it. The change had occurred by mid-2022. The study also found that readings fluctuated most among non-White patients. Grace A pulse oximeter estimates the level of oxygen in the blood. The researchers compared its readings with arterial blood gas test results. The NIH study abstract says they analyzed 223,145 tests from 15,129 patients, using intensive-care data from 2020 through 2024. Grace The findings concern the devices tested at one hospital. They do not establish why the devices’ average error changed. They also do not show that every pulse oximeter behaves the same way. Grace The results connect with an earlier concern about missed low oxygen levels. A 2020 study using data from 178 intensive-care units found that Black patients were more likely than White patients to have critically low blood oxygen that pulse oximeters did not detect. The reported rates were 17 percent of measurements for Black patients and 6.2 percent for White patients. Grace These are different findings. The earlier study measured cases of critically low oxygen that devices missed. The newer study tracked how average device error changed over time, and found greater fluctuations among non-White patients. Together, they make performance across patient groups an important question. But they do not explain what caused the newer change. Grace The central point is that a pulse oximeter reading is an estimate. In the study, the estimates from the devices examined did not remain consistent over time. That is a reason to take readings seriously without treating one number as the whole picture. The study does not show whether its findings apply beyond the hospital and devices examined. Grace Thanks for listening to Slow English FM.
