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Wong KFM, Huang W, Ee DYH, Ng EYK. Design and validation of dual-point time-differentiated photoplethysmogram (2PPG) wearable for cuffless blood pressure estimation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 253:108251. [PMID: 38824806 DOI: 10.1016/j.cmpb.2024.108251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 05/02/2024] [Accepted: 05/24/2024] [Indexed: 06/04/2024]
Abstract
BACKGROUND & OBJECTIVES Measurement of blood pressure (BP) in ambulatory patients is crucial for at high-risk cardiovascular patients. A non-obtrusive, non-occluding device that continuously measures BP via photoplethysmography will enable long-term ambulatory assessment of BP. The aim of this study is to validate the metasense 2PPG cuffless wearable design for continuous BP estimation without ECG. METHODS A customized high-speed electronic optical sensor architecture with laterally spaced reflectance pulse oximetry was designed into a simple unobtrusive low-power wearable in the form of a watch. 78 volunteers with a mean age of 32.72 ± 7.4 years (21 to 64), 51% male, 49% female were recruited with ECG-2PPG signals acquired. The fiducial features of the 2PPG morphologies were then attributed to the estimator. A 9-1 K-fold cross-validation was applied in the ML. RESULTS The correlation for PTT-SBP was 0.971 and for PTT-DBP was 0.954. The mean absolute error was 3.167±1.636 mmHg for SBP and 6.4 ± 3.9 mm Hg for DBP. The ambulatory estimate for SBP and DBP for an individual over 3 days with 8-hour recordings was 0.70-0.81 for SBP and 0.42-0.51 for DBP with a ± 2.65 mmHg for SBP and ±2.02 mmHg for DBP. For SBP, 98% of metasense measurements were within 15 mm Hg and for DBP, 91% of metasense measurements were within 10 mmHg CONCLUSIONS: The metasense device provides continuous, non-invasive BP estimations that are comparable to ambulatory BP meters. The portability and unobtrusiveness of this device, as well as the ability to continuously measure BP could one day enable long-term ambulatory BP measurement for precision cardiovascular therapeutic regimens.
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Affiliation(s)
- Kei Fong Mark Wong
- School of Mechanical and Aerospace Engineering, Nanyang Technological University (NTU), Singapore
| | | | | | - Eddie Yin Kwee Ng
- School of Mechanical and Aerospace Engineering, Nanyang Technological University (NTU), Singapore.
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Yoon YH, Kim J, Lee KJ, Cho D, Oh JK, Kim M, Roh JH, Park HW, Lee JH. Blood Pressure Measurement Based on the Camera and Inertial Measurement Unit of a Smartphone: Instrument Validation Study. JMIR Mhealth Uhealth 2023; 11:e44147. [PMID: 37694382 PMCID: PMC10503482 DOI: 10.2196/44147] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 04/13/2023] [Accepted: 07/21/2023] [Indexed: 09/12/2023] Open
Abstract
Background Even though several mobile apps that can measure blood pressure have been developed, the data about the accuracy of these apps are limited. Objective We assessed the accuracy of AlwaysBP (test) in blood pressure measurement compared with the standard, cuff-based, manual method of brachial blood pressure measurement (reference). Methods AlwaysBP is a smartphone software that estimates systolic blood pressure (SBP) and diastolic blood pressure (DBP) based on pulse transit time (PTT). PTT was calculated with a finger photoplethysmogram and seismocardiogram using, respectively, the camera and inertial measurement unit sensor of a commercially available smartphone. After calculating PTT, SBP and DBP were estimated via the Bramwell-Hill and Moens-Korteweg equations. A calibration process was carried out 3 times for each participant to determine the input parameters of the equations. This study was conducted from March to August 2021 at Chungnam National University Sejong Hospital with 87 participants aged between 19 and 70 years who met specific conditions. The primary analysis aimed to evaluate the accuracy of the test method compared with the reference method for the entire study population. The secondary analysis was performed to confirm the stability of the test method for up to 4 weeks in 15 participants. At enrollment, gender, arm circumference, and blood pressure distribution were considered according to current guidelines. Results Among the 87 study participants, 45 (52%) individuals were male, and the average age was 35.6 (SD 10.4) years. Hypertension was diagnosed in 14 (16%) participants before this study. The mean test and reference SBPs were 120.0 (SD 18.8) and 118.7 (SD 20.2) mm Hg, respectively (difference: mean 1.2, SD 7.1 mm Hg). The absolute differences between the test and reference SBPs were <5, <10, and <15 mm Hg in 57.5% (150/261), 84.3% (220/261 ), and 94.6% (247/261) of measurements. The mean test and reference DBPs were 80.1 (SD 12.6) and 81.1 (SD 14.4) mm Hg, respectively (difference: mean -1.0, SD 6.0 mm Hg). The absolute differences between the test and reference DBPs were <5, <10, and <15 mm Hg in 75.5% (197/261), 93.9% (245/261), and 97.3% (254/261) of measurements, respectively. The secondary analysis showed that after 4 weeks, the differences between SBP and DBP were 0.1 (SD 8.8) and -2.4 (SD 7.6) mm Hg, respectively. Conclusions AlwaysBP exhibited acceptable accuracy in SBP and DBP measurement compared with the standard measurement method, according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization protocol criteria. However, further validation studies with a specific validation protocol designed for cuffless blood pressure measuring devices are required to assess clinical accuracy. This technology can be easily applied in everyday life and may improve the general population's awareness of hypertension, thus helping to control it.
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Affiliation(s)
- Yong-Hoon Yoon
- Chungnam National University Sejong Hospital, Sejong-Si, Republic of Korea
| | - Jongin Kim
- Deepmedi Research Institute of Technology, Seoul, Republic of Korea
| | - Kwang Jin Lee
- Deepmedi Research Institute of Technology, Seoul, Republic of Korea
| | - Dongrae Cho
- Deepmedi Research Institute of Technology, Seoul, Republic of Korea
| | - Jin Kyung Oh
- Chungnam National University Sejong Hospital, Sejong-Si, Republic of Korea
| | - Minsu Kim
- Chungnam National University Sejong Hospital, Sejong-Si, Republic of Korea
| | - Jae-Hyung Roh
- Chungnam National University Sejong Hospital, Sejong-Si, Republic of Korea
| | - Hyun Woong Park
- Chungnam National University Sejong Hospital, Sejong-Si, Republic of Korea
| | - Jae-Hwan Lee
- Chungnam National University Sejong Hospital, Sejong-Si, Republic of Korea
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Guo CY, Perng JW, Chen LC, Hsieh TL. A Hemodynamic Pulse Wave Simulator Designed for Calibration of Local Pulse Wave Velocities Measurement for Cuffless Techniques. MICROMACHINES 2023; 14:1218. [PMID: 37374803 DOI: 10.3390/mi14061218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/18/2023] [Accepted: 06/08/2023] [Indexed: 06/29/2023]
Abstract
OBJECTIVE Devices for cuffless blood pressure (BP) measurement have become increasingly widespread in recent years. Non-invasive continuous BP monitor (BPM) devices can diagnose potential hypertensive patients at an early stage; however, these cuffless BPMs require more reliable pulse wave simulation equipment and verification methods. Therefore, we propose a device to simulate human pulse wave signals that can test the accuracy of cuffless BPM devices using pulse wave velocity (PWV). METHODS We design and develop a simulator capable of simulating human pulse waves comprising an electromechanical system to simulate the circulatory system and an arm model-embedded arterial phantom. These parts form a pulse wave simulator with hemodynamic characteristics. We use a cuffless device for measuring local PWV as the device under test to measure the PWV of the pulse wave simulator. We then use a hemodynamic model to fit the cuffless BPM and pulse wave simulator results; this model can rapidly calibrate the cuffless BPM's hemodynamic measurement performance. RESULTS We first used multiple linear regression (MLR) to generate a cuffless BPM calibration model and then investigated differences between the measured PWV with and without MLR model calibration. The mean absolute error of the studied cuffless BPM without the MLR model is 0.77 m/s, which improves to 0.06 m/s when using the model for calibration. The measurement error of the cuffless BPM at BPs of 100-180 mmHg is 1.7-5.99 mmHg before calibration, which decreases to 0.14-0.48 mmHg after calibration. CONCLUSION This study proposes a design of a pulse wave simulator based on hemodynamic characteristics and provides a standard performance verification method for cuffless BPMs that requires only MLR modeling on the cuffless BPM and pulse wave simulator. The pulse wave simulator proposed in this study can be used to quantitively assess the performance of cuffless BPMs. The proposed pulse wave simulator is suitable for mass production for the verification of cuffless BPMs. As cuffless BPMs become increasingly widespread, this study can provide performance testing standards for cuffless devices.
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Affiliation(s)
- Cheng-Yan Guo
- Accurate Meditech Inc., New Taipei City 241406, Taiwan
| | - Jau-Woei Perng
- Department of Mechanical and Electromechanical Engineering, National Sun Yat-sen University, 70 Lienhai Road, Kaohsiung 80424, Taiwan
| | - Li-Ching Chen
- LAICA International Corp, New Taipei City 231, Taiwan
| | - Tung-Li Hsieh
- Department of Electronics Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 80778, Taiwan
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Seo Y, Kwon S, Sunarya U, Park S, Park K, Jung D, Cho Y, Park C. Blood pressure estimation and its recalibration assessment using wrist cuff blood pressure monitor. Biomed Eng Lett 2023; 13:221-233. [PMID: 37124108 PMCID: PMC10130301 DOI: 10.1007/s13534-023-00271-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/02/2023] [Accepted: 02/16/2023] [Indexed: 05/02/2023] Open
Abstract
The rapid evolution of wearable technology in healthcare sectors has created the opportunity for people to measure their blood pressure (BP) using a smartwatch at any time during their daily activities. Several commercially-available wearable devices have recently been equipped with a BP monitoring feature. However, concerns about recalibration remain. Pulse transit time (PTT)-based estimation is required for initial calibration, followed by periodic recalibration. Recalibration using arm-cuff BP monitors is not practical during everyday activities. In this study, we investigated recalibration using PTT-based BP monitoring aided by a deep neural network (DNN) and validated the performance achieved with more practical wrist-cuff BP monitors. The PTT-based prediction produced a mean absolute error (MAE) of 4.746 ± 1.529 mmHg for systolic blood pressure (SBP) and 3.448 ± 0.608 mmHg for diastolic blood pressure (DBP) when tested with an arm-cuff monitor employing recalibration. Recalibration clearly improved the performance of both DNN and conventional linear regression approaches. We established that the periodic recalibration performed by a wrist-worn BP monitor could be as accurate as that obtained with an arm-worn monitor, confirming the suitability of wrist-worn devices for everyday use. This is the first study to establish the potential of wrist-cuff BP monitors as a means to calibrate BP monitoring devices that can reliably substitute for arm-cuff BP monitors. With the use of wrist-cuff BP monitoring devices, continuous BP estimation, as well as frequent calibrations to ensure accurate BP monitoring, are now feasible.
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Affiliation(s)
- Youjung Seo
- Department of Computer Engineering, Kwangwoon University, Seoul, 01897 Korea
| | - Saehim Kwon
- Department of Artificial Intelligence, Kwangwoon University, Seoul, 01897 Korea
| | - Unang Sunarya
- Department of Computer Engineering, Kwangwoon University, Seoul, 01897 Korea
- School of Applied Science, Telkom University, Bandung, 40257 Indonesia
| | - Sungmin Park
- Department of Convergence IT Engineering and the Department of Electrical Engineering, Pohang University of Science and Technology, Pohang, 37673 Korea
| | - Kwangsuk Park
- Department of Biomedical Engineering, College of Medicine, Seoul National University, Seoul, 03080 Korea
| | - Dawoon Jung
- Center for Artificial Intelligence, Korea Institute of Science and Technology, Seoul, 13916 Korea
| | - Youngho Cho
- Department of Electrical and Communication Engineering, University of Daelim, Anyang, 13916 Korea
| | - Cheolsoo Park
- Department of Computer Engineering, Kwangwoon University, Seoul, 01897 Korea
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Samimi H, Dajani HR. A PPG-Based Calibration-Free Cuffless Blood Pressure Estimation Method Using Cardiovascular Dynamics. SENSORS (BASEL, SWITZERLAND) 2023; 23:4145. [PMID: 37112490 PMCID: PMC10146008 DOI: 10.3390/s23084145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/18/2023] [Accepted: 04/19/2023] [Indexed: 06/19/2023]
Abstract
Traditional cuff-based sphygmomanometers for measuring blood pressure can be uncomfortable and particularly unsuitable to use during sleep. A proposed alternative method uses dynamic changes in the pulse waveform over short intervals and replaces calibration with information from photoplethysmogram (PPG) morphology to provide a calibration-free approach using a single sensor. Results from 30 patients show a high correlation of 73.64% for systolic blood pressure (SBP) and 77.72% for diastolic blood pressure (DBP) between blood pressure estimated with the PPG morphology features and the calibration method. This suggests that the PPG morphology features could replace the calibration stage for a calibration-free method with similar accuracy. Applying the proposed methodology on 200 patients and testing on 25 new patients resulted in a mean error (ME) of -0.31 mmHg, a standard deviation of error (SDE) of 4.89 mmHg, a mean absolute error (MAE) of 3.32 mmHg for DBP and an ME of -4.02 mmHg, an SDE of 10.40 mmHg, and an MAE of 7.41 mmHg for SBP. These results support the potential for using a PPG signal for calibration-free cuffless blood pressure estimation and improving accuracy by adding information from cardiovascular dynamics to different methods in the cuffless blood pressure monitoring field.
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Qin K, Huang W, Zhang T, Tang S. Machine learning and deep learning for blood pressure prediction: a methodological review from multiple perspectives. Artif Intell Rev 2022. [DOI: 10.1007/s10462-022-10353-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Cuffless Blood Pressure Estimation Using Calibrated Cardiovascular Dynamics in the Photoplethysmogram. Bioengineering (Basel) 2022; 9:bioengineering9090446. [PMID: 36134991 PMCID: PMC9495658 DOI: 10.3390/bioengineering9090446] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 08/23/2022] [Accepted: 08/28/2022] [Indexed: 11/19/2022] Open
Abstract
An important means for preventing and managing cardiovascular disease is the non-invasive estimation of blood pressure. There is particular interest in developing approaches that provide accurate cuffless and continuous estimation of this important vital sign. This paper proposes a method that uses dynamic changes of the pulse waveform over short time intervals and calibrates the system based on a mathematical model that relates reflective PTT (R-PTT) to blood pressure. An advantage of the method is that it only requires collecting the photoplethysmogram (PPG) using one optical sensor, in addition to initial non-invasive measurements of blood pressure that are used for calibration. This method was applied to data from 30 patients, resulting in a mean error (ME) of 0.59 mmHg, a standard deviation of error (SDE) of 7.07 mmHg, and a mean absolute error (MAE) of 4.92 mmHg for diastolic blood pressure (DBP) and an ME of 2.52 mmHg, an SDE of 12.15 mmHg, and an MAE of 8.89 mmHg for systolic blood pressure (SBP). These results demonstrate the possibility of using the PPG signal for the cuffless continuous estimation of blood pressure based on the analysis of calibrated changes in cardiovascular dynamics, possibly in conjunction with other methods that are currently being researched.
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Heimark S, Rindal OMH, Seeberg TM, Stepanov A, Boysen ES, Bøtker-Rasmussen KG, Mobæk NK, Søraas CL, Stenehjem AE, Fadl Elmula FEM, Waldum-Grevbo B. Blood pressure altering method affects correlation with pulse arrival time. Blood Press Monit 2022; 27:139-146. [PMID: 34855653 PMCID: PMC8893131 DOI: 10.1097/mbp.0000000000000577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 11/07/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Pulse arrival time (PAT) is a potential main feature in cuff-less blood pressure (BP) monitoring. However, the precise relationship between BP parameters and PAT under varying conditions lacks a complete understanding. We hypothesize that simple test protocols fail to demonstrate the complex relationship between PAT and both SBP and DBP. Therefore, this study aimed to investigate the correlation between PAT and BP during two exercise modalities with differing BP responses using an unobtrusive wearable device. METHODS Seventy-five subjects, of which 43.7% had a prior diagnosis of hypertension, participated in an isometric and dynamic exercise test also including seated periods of rest prior to, in between and after. PAT was measured using a prototype wearable chest belt with a one-channel electrocardiogram and a photo-plethysmography sensor. Reference BP was measured auscultatory. RESULTS Mean individual correlation between PAT and SBP was -0.82 ± 0.14 in the full protocol, -0.79 ± 0.27 during isometric exercise and -0.77 ± 0.19 during dynamic exercise. Corresponding correlation between PAT and DBP was 0.25 ± 0.35, -0.74 ± 0.23 and 0.39 ± 0.41. CONCLUSION The results confirm PAT as a potential main feature to track changes in SBP. The relationship between DBP and PAT varied between exercise modalities, with the sign of the correlation changing from negative to positive between type of exercise modality. Thus, we hypothesize that simple test protocols fail to demonstrate the complex relationship between PAT and BP with emphasis on DBP.
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Affiliation(s)
- Sondre Heimark
- Department of Nephrology, Oslo University Hospital
- Section for Cardiovascular and Renal Research, Oslo University Hospital
- Institute of Clinical Medicine, University of Oslo
| | | | | | | | | | | | | | - Camilla L. Søraas
- Section for Cardiovascular and Renal Research, Oslo University Hospital
- Section for Environmental and Occupational Medicine, Oslo University Hospital
| | | | - Fadl Elmula M. Fadl Elmula
- Section for Cardiovascular and Renal Research, Oslo University Hospital
- Department of Acute Medicine, Oslo University Hospital, Oslo, Norway
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Dervieux E, Théron M, Uhring W. Carbon Dioxide Sensing-Biomedical Applications to Human Subjects. SENSORS (BASEL, SWITZERLAND) 2021; 22:188. [PMID: 35009731 PMCID: PMC8749784 DOI: 10.3390/s22010188] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/13/2021] [Accepted: 12/20/2021] [Indexed: 02/06/2023]
Abstract
Carbon dioxide (CO2) monitoring in human subjects is of crucial importance in medical practice. Transcutaneous monitors based on the Stow-Severinghaus electrode make a good alternative to the painful and risky arterial "blood gases" sampling. Yet, such monitors are not only expensive, but also bulky and continuously drifting, requiring frequent recalibrations by trained medical staff. Aiming at finding alternatives, the full panel of CO2 measurement techniques is thoroughly reviewed. The physicochemical working principle of each sensing technique is given, as well as some typical merit criteria, advantages, and drawbacks. An overview of the main CO2 monitoring methods and sites routinely used in clinical practice is also provided, revealing their constraints and specificities. The reviewed CO2 sensing techniques are then evaluated in view of the latter clinical constraints and transcutaneous sensing coupled to a dye-based fluorescence CO2 sensing seems to offer the best potential for the development of a future non-invasive clinical CO2 monitor.
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Affiliation(s)
- Emmanuel Dervieux
- BiOSENCY, 1137a Avenue des Champs Blancs, 35510 Cesson-Sévigné, France
| | - Michaël Théron
- ORPHY, Université de Bretagne Occidentale, 6 Avenue Victor le Gorgeu, 29238 Brest, France;
| | - Wilfried Uhring
- ICube, University of Strasbourg and CNRS, 23 rue du Loess, CEDEX, 67037 Strasbourg, France;
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