Abstract
This study presents a new blood pressure (BP) estimation algorithm utilizing machine learning (ML). A cuffless device that can measure BP without calibration would be precious for portability, continuous measurement, and comfortability, but unfortunately, it does not currently exist. Conventional BP measurement with a cuff is standard, but this method has various problems like inaccurate BP measurement, poor portability, and painful cuff pressure. To overcome these disadvantages, many researchers have developed cuffless BP estimation devices. However, these devices are not clinically applicable because they require advanced preparation before use, such as calibration, do not follow international standards (81060-1:2007), or have been designed using insufficient data sets. The present study was conducted to combat these issues. We recruited 127 participants and obtained 878 raw datasets. According to international standards, our diverse data set included participants from different age groups with a wide variety of blood pressures. We utilized ML to formulate a BP estimation method that did not require calibration. The present study also conformed to the method required by international standards while calculating the level of error in BP estimation. Two essential methods were applied in this study: (a) grouping the participants into five subsets based on the relationship between the pulse transit time and systolic BP by a support vector machine ensemble with bagging (b) applying the information from the wavelet transformation of the pulse wave and the electrocardiogram to the linear regression BP estimation model for each group. For systolic BP, the standard deviation of error for the proposed BP estimation results with cross-validation was 7.74 mmHg, which was an improvement from 17.05 mmHg, as estimated by the conventional pulse-transit-time-based methods. For diastolic BP, the standard deviation of error was 6.42 mmHg for the proposed BP estimation, which was an improvement from 14.05mmHg. The purpose of the present study was to demonstrate and evaluate the performance of the newly developed BP estimation ML method that meets the international standard for non-invasive sphygmomanometers in a population with a diverse range of age and BP.
Highlights
Non-invasive blood pressure (BP) measurement with cuff-based devices is widely used, and these devices are necessary for various medical situations [1]
For systolic blood pressure (SBP), the error of the standard deviation of the proposed BP estimation results with cross-validation was 7.74 mmHg, which was an improvement from 17.05 mmHg, as estimated by the conventional Pulse transit time (PTT)-based methods
For diastolic blood pressure (DBP), the error of the standard deviation of the proposed BP estimation results with cross-validation was 6.42 mmHg, which was an improvement from 14.05 mmHg, as estimated by the conventional PTT-based methods
Summary
Non-invasive blood pressure (BP) measurement with cuff-based devices is widely used, and these devices are necessary for various medical situations [1]. The PTT indirectly depends on blood pressure; the higher the pressure, the faster the PTT [11] This phenomenon has been used for non-invasive BP estimation. Many conventional cuffless PTT-based BP estimation studies have some drawbacks, divided into four categories: [1] analysis of biased, [2] small datasets, [3] studies with devices that required calibration, and [4] insufficient accuracy as required by international standards. Poon and Zhang’s cuffless BP measurement was the only study that had handled a large variety of participants’ blood pressures (39 with hypertension), range of age (57 ± 27 years old), and large participant number (85 participants) [21]. The BP estimation method in Poon and Zhang’s study had major shortcomings to need a calibration procedure for each participant, and the accuracy of BP estimation was not precise
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