Over the past 2 years, the pulse oximeter has become a crucial tool for tracking the health of COVID-19 patients.

The small device clips onto a finger and measures the amount of oxygen in a patient’s blood. But a growing body of evidence shows the device can be inaccurate when measuring oxygen levels in people with dark skin tones.

A recent study has added to this concern.

“We were fooled by the pulse oximeter,” says the study’s lead author Dr Leo Anthony Celi, who’s clinical research director and principal research scientist at the MIT Laboratory of Computational Physiology.

“We were given the false impression that the patients were okay. And what we showed in this study is that we were giving them less oxygen than they needed,” he says.

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