A Web-based, Smartphone-enabled Algorithm for Calculating Blood Pressure Remotely using Photoplethysmogram (PPG) Waveforms: Observational Study (Preprint)
BACKGROUND The current gold standard instrument for measuring blood pressure is a mercury-filled sphygmomanometer with a cuff and stethoscope. However, this is not convenient or feasible for remote monitoring and virtual care. HeartBeat Technologies Ltd. developed a novel approach to measuring blood pressure remotely after an initial blood pressure reading using the conventional measurement method. Using a finger pulse oximeter, a photoplethysmogram wave (PPG) is transmitted by Bluetooth to a smartphone or tablet. An application called MediBeat on the smartphone transmits the PPG to a server where a proprietary algorithm analyzes it to calculate the person’s current blood pressure level and sends the level back to the smartphone and the device of the individual’s healthcare provider. OBJECTIVE This study sought to determine whether the HeartBeat algorithm calculates blood pressure as accurately as required by the European Society of Hypertension International Protocol revision 2010 (ESH-IP2) for validation of blood pressure measuring devices. METHODS The ESH-IP2, modified to conform to a more recent international consensus statement, was followed. The ESH-IP2 establishes strict guidelines for the conduct and reporting of any validation of any device to measure blood pressure, including using the gold standard manual blood pressure instrument as a comparator and specific required accuracy levels for low, medium and high ranges of blood pressure readings. The consensus statement requires a greater number of study participants for each of the blood pressure ranges. The validation of the accuracy of the algorithm was conducted in conjunction with a Contec CMS50EW pulse oximeter and a Samsung Galaxy XCover 4 smartphone. RESULTS The differences between the HeartBeat-calculated and the manually-measured blood pressures did not meet the ESH-IP2 standards for accuracy for either systolic or diastolic blood pressure measurements. There was no discernible pattern in the inaccuracies in the HeartBeat-calculated measures. CONCLUSIONS The current version of the HeartBeat algorithm, implemented in combination with the MediBeat application, the specific pulse oximeter and the Android smartphones, is not accurate for use in the general population. CLINICALTRIAL This study was registered with ClinicalTrials.gov (ClinicalTrials.gov ID: NCT04082819).