Abstract
Cuffless blood pressure (BP) measurement is an all-inclusive term for a method that aims to measure BP without using a cuff. Recent cuffless technology has made it possible to estimate BP with reasonable accuracy. However, mainstream methods require an electrocardiogram and photoplethysmogram measurements, and frequent calibration procedures using a cuff sphygmomanometer. We therefore developed a far simpler cuffless method, using only heart rate (HR) and modified normalized pulse volume (mNPV) that can be measured using a smartphone, based on the knowledge that ln BP = ln cardiac output (CO) + ln total peripheral resistance (TPR), where CO and TPR are correlated with HR and mNPV, respectively. Here, we show that mean arterial pressure (MAP), systolic BP (SBP), and diastolic BP (DBP) could be estimated using the exponential transformation of linear polynomial equation, (a × ln HR) + (b × ln mNPV) + constant, using only a smartphone, with an accuracy of R > 0.70. This implies that our cuffless method could convert a large number of smartphones or smart watches into simplified sphygmomanometers.
Highlights
Cuffless blood pressure (BP) measurement is an all-inclusive term for a method that aims to measure BP without using a cuff
The present findings offer a simple and moderately reliable cuffless method for estimating BP using only a smartphone, as well as a traditional finger photoplethysmograph
The estimated mean arterial pressure (MAP), systolic BP (SBP), and diastolic BP (DBP) attained an accuracy of R > 0.70 (Fig. 2) when compared to a standard brachial cuff sphygmomanometer, across gender and across baseline and stress conditions, where pre-ejection period (PEP), one of the major error sources of the pulse wave velocity (PWV)-based method[12,14,16,17,39,40], is expected to differ[41], without relying on a complicated individual calibration procedure and on any other devices such as an ECG and dedicated PPG11,16,21
Summary
Cuffless blood pressure (BP) measurement is an all-inclusive term for a method that aims to measure BP without using a cuff. We show that mean arterial pressure (MAP), systolic BP (SBP), and diastolic BP (DBP) could be estimated using the exponential transformation of linear polynomial equation, (a × ln HR) + (b × ln mNPV) + constant, using only a smartphone, with an accuracy of R > 0.70 This implies that our cuffless method could convert a large number of smartphones or smart watches into simplified sphygmomanometers. The most significant early advance in non-invasive BP measurement came in 1896 with the introduction of the ‘Riva Rocci mercury sphygmomanometer’, which was able to estimate systolic BP (SBP) With this device an inflatable rubber cuff was applied around the upper arm, and a mercury column used to measure the cuff pressure during an inflation-deflation sequence. Effect Size d the PWV-based method usually requires an elaborate individual calibration process using a sphygmomanometer with a cuff e.g.11,19,20, and cannot be used as a replacement for a cuff sphygmomanometer[21]
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