Wearable pulse oximeters in the prompt detection of hypoxaemia and during movement: a diagnostic accuracy study (Preprint)
Santos M., Vollam S., Pimentel MAF., Areia C., Young L., Roman C., Ede J., Piper P., King E., Harford M., Shah A., Gustafson O., Tarassenko L., Watkinson P.
BACKGROUND Commercially available wearable (ambulatory) pulse oximeters have been recommended as a method for managing patients at risk of physiological deterioration, such as active patients with COVID-19 disease receiving care in hospital isolation rooms, however, their reliability is unclear to use in the hospital setting. OBJECTIVE We report the performance of wearable pulse oximeters in a simulated clinical setting when challenged by motion and low levels of arterial blood oxygen (SaO2). METHODS The performance of one wrist-worn (Wavelet) and three finger-worn (CheckMeTM O2+, AP-20 and WristOx2® 3150) wearable, wireless transmission-mode, pulse oximeters was evaluated. Seven motion tasks were performed: At rest, Sit-to-Stand, Tapping, Rubbing, Drinking, Turning Pages, and Using a Tablet. Hypoxia exposure followed, in which inspired gases were adjusted to achieve decreasing SaO2 levels at 100%, 95%, 90%, 87%, 85%, 83% and 80%. Peripheral oxygen saturation (SpO2) estimates were compared with simultaneous SaO2 samples to calculate the root mean squared error (RMSE). Area under the receiver-operating characteristic curve was used to analyse the detection of hypoxaemia, SaO2 < 90%. RESULTS SpO2 estimates matching 215 SaO2 samples in both study phases, from 33 participants, were analysed. Tapping, rubbing, turning pages and using a tablet degraded SpO2 estimation (RMSE > 4% for a least one device). All finger-worn pulse oximeters detected hypoxaemia, with an overall sensitivity ≥ 0.87 and specificity ≥ 0.80, comparable to that of the Philips MX450. CONCLUSIONS The SpO2 accuracy of wearable finger-worn pulse oximeters was within that required by the International Organization for Standardization guidelines. Performance was degraded by motion, but all were capable of detecting hypoxaemia. Our findings support the use of wearable, wireless transmission-mode, pulse oximeters to detect the onset of clinical deterioration in hospital settings. CLINICALTRIAL ISRCTN61535692; http://www.isrctn.com/ISRCTN61535692 INTERNATIONAL REGISTERED REPORT RR2-10.1136/bmjopen-2019-034404