Why Apple Watch Series 6’s blood oxygen monitor didn’t require FDA approval

Apple Watch Series 6 expands the health capabilities of previous Apple Watch models with a new blood oxygen feature that conveniently measures the oxygen saturation of the user’s blood, so they can better understand their overall fitness and wellness. Oxygen saturation, or SpO2, represents the percentage of oxygen being carried by red blood cells from the lungs to the rest of the body, and indicates how well this oxygenated blood is being delivered throughout the body.

The Blood Oxygen sensor employs LEDs, along with photodiodes on the back crystal of Apple Watch Series 6.
The Blood Oxygen sensor employs LEDs, along with photodiodes on the back crystal of Apple Watch Series 6.

To compensate for natural variations in the skin and improve accuracy, the Blood Oxygen sensor employs four clusters of green, red, and infrared LEDs, along with the four photodiodes on the back crystal of Apple Watch, to measure light reflected back from blood. Apple Watch then uses an advanced custom algorithm built into the Blood Oxygen app, which is designed to measure blood oxygen between 70 percent and 100 percent. On-demand measurements can be taken while the user is still, and periodic background measurements occur when they are inactive, including during sleep. All data will be visible in the Health app, and the user will be able to track trends over time to see how their blood oxygen level changes.

Nicole Wetsman for The Verge:

The features on the Apple Watch that track heart rate and heart rhythm, though, have a key difference from the blood oxygen monitor: the heart-tracking features are cleared by the Food and Drug Administration (FDA), and the oxygen monitor is not. Apple went through a long, extensive process to develop and validate an EKG feature so that the watch could detect a condition called atrial fibrillation. It didn’t need to do the same thing for the pulse oximeter.

Blood oxygen monitors, or pulse oximeters, are considered Class II medical devices by the FDA. Generally, any company that wants to sell one in the United States has to submit documentation to the agency confirming that its product works just as well as other versions of the same product already on the market. There’s a workaround, though: if the company says that the product is just for fun, or for general “wellness,” they don’t have to go through that process. They can’t claim that it can diagnose or treat any medical conditions, but they can put it up for sale.

That’s the route Apple went down… Other health-focused apps and smartwatches have taken the same approach…

MacDailyNews Take: Regardless, Apple is joining forces with researchers to conduct three health studies that include using Apple Watch to explore how blood oxygen levels can be used in future health applications.

This year, Apple will collaborate with the University of California, Irvine, and Anthem to examine how longitudinal measurements of blood oxygen and other physiological signals can help manage and control asthma.

Apple will also work closely with investigators at the Ted Rogers Centre for Heart Research and the Peter Munk Cardiac Centre at the University Health Network, one of the largest health research organizations in North America, to better understand how blood oxygen measurements and other Apple Watch metrics can help with management of heart failure.

Additionally, investigators with the Seattle Flu Study at the Brotman Baty Institute for Precision Medicine and faculty from the University of Washington School of Medicine will seek to learn how signals from apps on Apple Watch, such as Heart Rate and Blood Oxygen, could serve as early signs of respiratory conditions like influenza and COVID-19.

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