Maxim Integrated Smartphone Sensor with App Meets FDA/ISO Standards for Clinical Pulse Oximetry and can be Reliably Utilized by a Wide Range of Patients.

Browne, Sara H.; Bernstein, Mike; Pan, Samuel C.; Garcia, Jonathan Gonzalez; Easson, Craig A.; Huang, Chung-Che; Vaida, Florin

Background Millions of smartphones contain a photoplethysmography (PPG) bio-sensor (Maxim Integrated, San Jose CA) that accurately measures pulse oximetry. No clinical use of these embedded sensors is currently being made, despite the relevance of remote clinical pulse oximetry to the management of chronic cardiopulmonary disease, and the triage, initial management and remote monitoring of persons effected by respiratory viral pandemics, such as SARS-CoV-2 or Influenza. To be used for clinical pulse oximetry the embedded PPG system must be paired with an App and meet FDA and ISO requirements. Research Question We evaluated whether this smartphone sensor with App met FDA/ISO requirements and how measurements obtained using this system compared to hospital reference devices across a wide range of persons. Study Design and Methods We performed laboratory testing addressing ISO and FDA requirements in ten participants using the smartphone sensor with App. Subsequently, we performed an open label clinical study on 320 participants with widely varying characteristics, to compare accuracy and precision of readings obtained by patients, to hospital reference devices using a rigorous statistical methodology. Results ‘Breathe Down’ testing in the laboratory showed that the total Root Mean Square Deviation (RSMD) of SpO2 measurement was 2.02%, meeting FDA/ISO standards. Clinical comparison of the smartphone sensor with App versus hospital reference devices determined SpO2 and heart rate (HR) accuracy was 0.48 % points (CI 0.38 to 0.58; p<0.001) and 0.73 bpm (CI 0.33 to 1.14; p<0.001) respectively; with SpO2 and HR precision 1.25 versus reference 0.95 points (p< 0.001) and 5.99 versus reference 3.80 bpm (p<0.001), respectively. These small differences were similar to the variation found between two FDA approved reference instruments for SpO2: accuracy 0.52 points (CI 0.41 to 0.64; p<0.001) and precision 1.01 versus 0.86 (p<0.001). Interpretation Our findings support the application for full FDA/ISO approval of the smartphone sensor with App tested for use in clinical pulse oximetry. Given the immense and immediate practical medical importance of remote intermittent clinical pulse oximetry to both chronic disease management and the global ability to respond to respiratory viral pandemics, the smartphone sensor with APP should be prioritized and fast tracked for FDA/ ISO approval to allow clinical use.