The Apple Watch’s blood oxygen sensor is as reliable as a medical grade device. A new study published that tested the Apple Watch’s blood oxygen monitoring function.
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According to the results of the study, the Apple Watch Series 6 is able to “reliably detect states of reduced oxygen saturation in the blood” even compared to medical-grade pulse oximeters.
The study was published this month in the open access journal Digital Health. The goal of the study was to verify how a commercially available smartwatch that measures peripheral blood oxygen saturation (SpO2) is able to detect hypoxemia compared to a medical-grade pulse oximeter.
For the study, the researchers recruited 24 healthy participants. Each person wore an Apple Watch Series 6 on their left wrist and a pulse oximeter sensor on their left middle finger (Masimo Radical-7).
Participants breathed through a breathing circuit with a three-way valve. First of all, in the initial 2-minute stabilization phase, the participants inhaled the ambient air. Then, in the 5-minute desaturation phase, the participants breathed in the oxygen-reduced gas mixture (12% O2), which temporarily lowered the oxygen saturation in the blood.
In the final stabilization phase, the participants inhaled the ambient air again until the SpO2 returned to normal values. SpO2 measurements were taken simultaneously by the smartwatch and the pulse oximeter at 30-second intervals.
The study produced 642 pairs of individual blood oxygen measurements. Differences in individual measurements between the smartwatch and the oximeter within 6% can be expected for SpO2 readings from 90% to 100% and up to 8% for SpO2 readings below 90%.
The researchers therefore conclude that “the SpO2 distortion between the smartwatch and the oximeter was 0.0% for all data points. The bias for SpO2 of less than 90% was 1.2%. The differences in individual measurements between the smartwatch and the oximeter can be within 6% of SpO2 for SpO2 readings between 90% and 100% and up to 8% for SpO2 readings below 90% “