Withings' ScanWatch can measure SpO2 levels with clinical-grade accuracy: study

Study data published Monday in the Journal of Medical Internet Research suggest that Withings' ScanWatch is able to adequately measure pulse oximetry (SpO2) levels with clinical-grade accuracy. "Currently, no mass-market wrist-worn SpO2 monitor meets the medical standards for pulse oximeters," the authors said, adding "we have demonstrated that the reflective pulse oximeter function of the Withings ScanWatch is adequate to measure the SpO2 levels at different stages of hypoxia."

The smartwatch is embedded with a heart rate sensor and displays a reflective pulse oximeter function to measure, transfer, record and display SpO2 levels. Researchers tested the accuracy of this functionality at a clinical-grade level. Specifically, the primary analysis was to evaluate the watch at different stages of hypoxia, while the secondary objective was to confirm the safety of the device.

ScanWatch was compared with Radiometer Medical's ABL90 haemoximeter, a co-oximeter routinely used for measuring SaO2 levels in blood samples. In the study, SpO2 levels were measured in 14 participants who underwent plateaus of oxygen desaturation in the laboratory.

A series of measurements were obtained with the ScanWatches on each participant's right and left wrists, evenly distributed among the three predetermined groups – SpO2 levels ≤ 80%, SpO2 between 80% and 90%, and SpO2 < 90%. The authors noted a "strong association and a high level of agreement between the measurements collected from the devices," with no reports of undesirable effects or adverse events.

Detection of sleep apnoeas

"In addition to the accuracy of 3% found in the hypoxia study, the ScanWatch SpO2 algorithm possesses adequate resolution and dynamics to identify apnoea and hypopnea events when worn during sleep," the authors noted. "Indeed, when used in a continuous monitoring mode, the ScanWatch can detect short SpO2 variations that occur in apnoeic patients, paving the way for automatic sleep apnoea detection for patients at home without using intrusive and costly polysomnography setups," they added.

Withings unveiled ScanWatch last year as the first hybrid smartwatch to combine medical-grade electrocardiogram and sleep apnoea detection.

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