Performance of a Wearable Ring in Controlled Hypoxia: A Prospective Observational Study

Area of Science:

• Biomedical Engineering
• Medical Device Technology
• Clinical Diagnostics

Background:

• Wearable technology advances enable continuous home monitoring of heart rate and oxygen saturation.
• Current consumer wearables may lack accuracy for medical decisions, especially with low saturation or dark skin.
• Clinical-grade wearable pulse oximetry offers valuable data for chronic disease management.

Purpose of the Study:

• To assess the accuracy of a wearable ring pulse oximeter against arterial oxygen saturation (SaO2).
• To validate device performance across various skin tones (Fitzpatrick I-VI) under controlled hypoxia.
• To compare accuracy with a clinical-grade reference device, adhering to ISO 80601-2-61:2019 standards.

Main Methods:

• A single-center, blinded hypoxia study was conducted with 11 healthy volunteers.
• A wearable test device and a Masimo Radical-7 reference device were used for SpO2 measurements.
• Arterial oxygen saturation (SaO2) was determined via blood gas analysis using an ABL-90 oximeter.

Main Results:

• The wearable ring achieved a root mean square error (RMSE) of 2.1%, surpassing the ISO standard (≤4%) and FDA guidance (≤3.5%).
• The reference Masimo Radical-7 device showed an RMSE of 2.8%.
• For participants with darker skin, the wearable device demonstrated excellent accuracy with RMSEs of 1.8% (finger) and 1.6% (fingertip).

Conclusions:

• The wearable ring pulse oximeter meets acceptable clinical-grade accuracy standards for SpO2 monitoring.
• Performance is consistent across different skin colors under non-motion conditions.
• The device is suitable for reliable SpO2 tracking in patients with chronic conditions.