Smartphone Biosensor With App Meets FDA/ISO Standards for Clinical Pulse Oximetry and Can Be Reliably Used by a Wide Range of Patients

Abstract

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 SpO 2 measurement was 2.02%, meeting FDA/ISO standards. Clinical comparison of the smartphone sensor with App versus hospital reference devices determined SpO 2 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 SpO 2 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 SpO 2 : 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.

Accuracy of Samsung Smartphone Integrated Pulse Oximetry Meets Full FDA Clearance Standards for Clinical Use

“…Most recently, Browne et al reported findings from clinical studies on 320 participants that utilized a repeated measure, nested factorial design to evaluate the accuracy and precision of a smartphone model, containing Maxim Integrated biosensors and App in comparison to Welch Allyn reference units. 24 Their results indicated a wide range of adult persons utilized a smartphone model to perform repeated pulse oximeter spot checks with an accuracy and precision equivalent to hospital grade clip sensors. 24 This clinical study had few hypoxemic patients, but did report human steady state hypoxia testing of the smartphone model versus a portable reference device that indicated FDA/ISO requirements were likely to be met if full testing was conducted.…”

“…24 Their results indicated a wide range of adult persons utilized a smartphone model to perform repeated pulse oximeter spot checks with an accuracy and precision equivalent to hospital grade clip sensors. 24 This clinical study had few hypoxemic patients, but did report human steady state hypoxia testing of the smartphone model versus a portable reference device that indicated FDA/ISO requirements were likely to be met if full testing was conducted. 24…”

“…24 This clinical study had few hypoxemic patients, but did report human steady state hypoxia testing of the smartphone model versus a portable reference device that indicated FDA/ISO requirements were likely to be met if full testing was conducted. 24…”

“…Studies testing similar hardware and algorithms reported high SpO 2 measurement accuracy. 24, 22 All future studies evaluating smartphone oximetry accuracy should specify the type of embedded hardware including biosensor manufacturer, App proprietor and site of placement within the smartphone, as these features constitute the actual oximetry device…”

Application of an evidence-based, out-patient treatment strategy for COVID-19: Multidisciplinary medical practice principles to prevent severe disease

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