Health & medicine

Missed signals: the limits of the pulse oximeter

In February, the US FDA issued a warning about the limitations of pulse oximeters, listing factors that might lead to inaccurate readings. This followed on from a study in the NEJM, which found that pulse oximeters had a higher error rate in Black patients. Why does this happen, and what does the issue tell us about the limitations of this technology? Abi Millar investigates.

In December, it emerged that pulse oximetry – a commonly used technology for measuring blood oxygen levels – may not be as accurate in Black patients as it is in white ones.

Writing in the New England Journal of Medicine (NEJM), researchers at the University of Michigan stated that Black patients in their sample were far more likely to suffer hypoxemia (low oxygen in the blood) that went undetected by pulse oximeters.

The researchers looked at patients who, according to pulse oximeter readings, had a blood oxygen saturation of 92%-96%. They re-tested these patients via an arterial blood gas test – a more accurate tool used in hospital settings.

A shocking 11.7% of the Black patients had levels under 88%, a level at which medical professionals would likely take action. This compared to just 3.6% of white patients.

Read the rest of this article in the May 2021 edition of Medical Technology

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