Key result
Novel cuffless MEMS-ECG monitor estimates blood pressure within ~2 mmHg of commercial cuff devices.
Why the study?
PPG-based pulse transit time systems require precise light adjustment and regular calibration, prompting the development of a cuffless blood pressure monitor using a microphone instead.
Does a real-time cuffless blood pressure monitor using a microphone and ECG accurately measure blood pressure compared to a commercial cuff monitor?
Does a real-time cuffless blood pressure monitor using a microphone and ECG accurately measure blood pressure compared to a commercial cuff monitor?
Effect estimate: MAE 2.29 ± 3.53 mmHg for SBP and 2.72 ± 3.42 mmHg for DBP
A novel cuffless blood pressure monitor utilizing a microphone and ECG showed promising initial accuracy in a single-subject proof-of-concept study, potentially eliminating the need for regular device calibration.
Warrants larger validation before clinical use; leaves open feasibility of calibration-free acoustic PTT cuffless BP monitoring.
Research has shown that pulse transit time (PTT), which is the time delay between the electrocardiogram (ECG) signal and the signal from a photoplethysmogram (PPG) sensor, can be used to estimate systolic blood pressure (SBP) and diastolic blood pressure (DBP) without the need for a cuff. However, the LED of the PPG sensor requires the precise adjustment of both light intensity and light absorption rates according to the contact status of the light-receiving element. This results in the need for regular calibration. In this study, we propose a cuffless blood pressure monitor that measures real-time blood pressure using a microphone instead of a PPG sensor. The blood pulse wave is measured in the radial artery of the wrist using a microphone that can directly measure the sound generated by a body rather than sending energy inside the body and receiving a returning signal. Our blood pressure monitor uses the PTT between the R-peak of the ECG signal and two feature points of the blood pulse wave in the radial artery of the wrist. ECG electrodes and circuits were fabricated, and a commercial microelectromechanical system (MEMS) microphone was used as the microphone to measure blood pulses. The peak points of the blood pulse from the microphone were clear, so the estimated SBP and DBP could be obtained from each ECG pulse in real time, and the resulting estimations were similar to those made by a commercial cuff blood pressure monitor. Since neither the ECG electrodes nor the microphone requires calibration over time, the real-time cuffless blood pressure monitor does not require calibration. Using the developed device, blood pressure was measured three times daily for five days, and the mean absolute error (MAE) and standard deviation (SD) of the SBP and DBP were found to be 2.72 ± 3.42 mmHg and 2.29 ± 3.53 mmHg, respectively. As a preliminary study for proof-of-concept, these results were obtained from one subject. The next step will be a pilot study on a large number of subjects.
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Choi et al. (2023) studied this question. Cuffless blood pressure monitor using MEMS microphone and ECG vs. Commercial brachial cuff-type blood pressure monitor (OMRON HEM-7120) was evaluated on Mean absolute error (MAE) and standard deviation (SD) of systolic (SBP) and diastolic blood pressure (DBP) (MAE 2.29 ± 3.53 mmHg for SBP and 2.72 ± 3.42 mmHg for DBP). A novel cuffless blood pressure monitor using a MEMS microphone and ECG estimated systolic and diastolic blood pressure with mean absolute errors of 2.29 mmHg and 2.72 mmHg, respectively, in a single subject.
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