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Celler BG, Yong A, Rubenis I, Butlin M, Argha A, Rehan R, Avolio A. Comparison of cuff inflation and cuff deflation brachial sphygmomanometry with intra-arterial blood pressure as reference. J Hypertens 2024; 42:968-976. [PMID: 38230615 DOI: 10.1097/hjh.0000000000003659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Conventional sphygmomanometry with cuff deflation is used to calibrate all noninvasive BP (NIBP) instruments and the International Standard makes no mention of calibrating methods specifically for NIBP instruments, which estimate systolic and diastolic pressure during cuff inflation rather than cuff deflation. There is however increasing interest in inflation-based NIBP (iNIBP) instruments on the basis of shorter measurement time, reduction in maximal inflation pressure and improvement in patient comfort and outcomes. However, we have previously demonstrated that SBP estimates based on the occurrence of the first K1 Korotkoff sounds during cuff deflation can underestimate intra-arterial SBP (IA-SBP) by an average of 14 ± 10 mmHg. In this study, we compare the dynamics of intra-arterial blood pressure (IABP) measurements with sequential measurement of Korotkoff sounds during both cuff inflation and cuff deflation in the same individual. In 40 individuals aged 64.1 ± 9.6 years (range 36-86 years), the overall dynamic responses below the cuff were similar, but the underestimation error was significantly larger during inflation than deflation, increasing from 14 ± 10 to 19 ± 12 mmHg ( P < 0.0001). No statistical models were found which could compensate for this error as were found for cuff deflation. The statistically significant BP differences between inflation and deflation protocols reported in this study suggest different behaviour of the arterial and venous vasculature between arterial opening and closing which warrant further investigation, particularly for iNIBP devices reporting estimates during cuff inflation. In addition, measuring Korotkoff sounds during cuff inflation represents significant technical difficulties because of increasing pump motor noise.
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Affiliation(s)
- Branko G Celler
- Biomedical Systems Research Laboratory, University of New South Wales
| | - Andy Yong
- Concord Repatriation Hospital, Cardiology, University of Sydney
- Faculty of Medicine, Health and Human Sciences, Macquarie University
| | - Imants Rubenis
- Concord Repatriation Hospital, Cardiology, University of Sydney
| | - Mark Butlin
- Faculty of Medicine, Health and Human Sciences, Macquarie University
| | - Ahmadreza Argha
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, New South Wales, Australia
| | - Rajan Rehan
- Concord Repatriation Hospital, Cardiology, University of Sydney
| | - Alberto Avolio
- Faculty of Medicine, Health and Human Sciences, Macquarie University
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Celler BG, Yong A, Rubenis I, Butlin M, Argha A, Rehan R, Avolio A. Accurate detection of Korotkoff sounds reveals large discrepancy between intra-arterial systolic pressure and simultaneous noninvasive measurement of blood pressure with brachial cuff sphygmomanometry. J Hypertens 2024; 42:873-882. [PMID: 38230626 DOI: 10.1097/hjh.0000000000003651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Cardiovascular disease is the number 1 cause of death globally, with elevated blood pressure (BP) being the single largest risk factor. Hence, BP is an important physiological parameter used as an indicator of cardiovascular health. Noninvasive cuff-based automated monitoring is now the dominant method for BP measurement and irrespective of whether the oscillometric or the auscultatory method is used, all are calibrated according to the Universal Standard (ISO 81060-2:2019), which requires two trained operators to listen to Korotkoff K1 sounds for SBP and K4/K5 sounds for DBP. Hence, Korotkoff sounds are fundamental to the calibration of all NIBP devices. In this study of 40 lightly sedated patients, aged 64.1 ± 9.6 years, we compare SBP and DBP recorded directly by intra-arterial fluid filled catheters to values recorded from the onset (SBP-K) and cessation (DBP-K) of Korotkoff sounds. We demonstrate that whilst DBP-K measurements are in good agreement, with a mean difference of -0.3 ± 5.2 mmHg, SBP-K underestimates true intra-arterial SBP (IA-SBP) by an average of 14 ± 9.6 mmHg. The underestimation arises from delays in the re-opening of the brachial artery following deflation of the brachial cuff to below SBP. The reasons for this delay are not known but appear related to the difference between SBP and the pressure under the cuff as blood first begins to flow, as the cuff deflates. Linear models are presented that can correct the underestimation in SBP resulting in estimates with a mean difference of 0.2 ± 7.1 mmHg with respect to intra-arterial SBP.
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Affiliation(s)
- Branko G Celler
- Biomedical Systems Research Laboratory, University of New South Wales
| | - Andy Yong
- Concord Repatriation Hospital, Cardiology, University of Sydney
- Faculty of Medicine, Health and Human Sciences, Macquarie University
| | - Imants Rubenis
- Concord Repatriation Hospital, Cardiology, University of Sydney
| | - Mark Butlin
- Faculty of Medicine, Health and Human Sciences, Macquarie University
| | - Ahmadreza Argha
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
| | - Rajan Rehan
- Concord Repatriation Hospital, Cardiology, University of Sydney
| | - Alberto Avolio
- Faculty of Medicine, Health and Human Sciences, Macquarie University
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Argha A, Celler BG, Yong A, Rubenis I, Butlin M, Avolio A. New Perspectives on Non-invasive Blood Pressure Measurement. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38082761 DOI: 10.1109/embc40787.2023.10340757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Noninvasive blood pressure (NIBP) devices are calibrated against validated auscultation sphygmomanometers using Korotkoff sounds. This study aimed to investigate the timing of Korotkoff sounds in relation to pulse appearance in the brachial artery and values of intra-arterial blood pressure. Experiments were carried out on 15 participants, (14 males, 64.3 ± 10.4 years; one female, 86 yo), undergoing coronary angiography. A conventional occluding cuff, with a microphone for Korotkoff sounds, was placed on the upper arm (on the brachial artery). Intra-arterial blood pressure (IABP) was measured below the cuff with a fluid-filled catheter inserted via the radial artery and an external transducer. Finger photoplethysmography was used to measure brachial pulse wave velocity (PWV). Korotkoff sounds were processed electronically and custom algorithms identified the cuff pressure (CP) at which the first and last Korotkoff sounds were heard. PWV and max slope of the IABP pressure pulse were recorded to estimate arterial stiffness. The brachial artery closed at a CP of 132.0 ± 17.1 mmHg. Systolic and diastolic blood pressure (SBP and DBP) were 147.6 ± 14.3 and 72.7 ± 10.1 mmHg; mean pressure (MP, 100.1 ± 10.4 mmHg) was similar to MP derived from the peak of the oscillogram (98.5 ± 13.6 mmHg). Difference between IABP and CP recorded at first and last occurrence of Korotkoff sounds were, SBP: 19.0 ± 8.3 (range 2-29) mmHg, DBP: 4.0 ± 4.3 (range 2-12) mmHg. SBP derived from the onset of Korotkoff sounds can underestimate IABP by up to 19 mmHg. Since Korotkoff sounds are the recommended method mandated by the universal standard for the validation of blood pressure measuring devices, these errors are propagated through to all NIBP measurement devices irrespective of whether they use auscultatory or oscillometric methods.
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Automated 'oscillometric' blood pressure measuring devices: how they work and what they measure. J Hum Hypertens 2023; 37:93-100. [PMID: 35637256 PMCID: PMC9957730 DOI: 10.1038/s41371-022-00693-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/27/2022] [Accepted: 04/07/2022] [Indexed: 11/09/2022]
Abstract
Automated 'oscillometric' blood pressure (BP) measuring devices (BPMDs) were developed in the 1970s to replace manual auscultatory BP measurement by mercury sphygmomanometer. Automated BPMDs that have passed accuracy testing versus a reference auscultatory sphygmomanometer using a scientifically accepted validation protocol are recommended for clinical use globally. Currently, there are many thousands of unique automated BPMDs manufactured by hundreds of companies, with each device using proprietary algorithms to estimate BP and using a method of operation that is largely unchanged since inception. Validated automated BPMDs provide similar BP values to those recorded using manual auscultation albeit with potential sources of error mostly associated with using empirical algorithms to derive BP from waveform pulsations. Much of the work to derive contemporary BP thresholds and treatment targets used to manage cardiovascular disease risk was obtained using automated BPMDs. While there is room for future refinement to improve accuracy for better individual risk stratification, validated BPMDs remain the recommended standard for office and out-of-office BP measurement to be used in hypertension diagnosis and management worldwide.
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Celler BG, Argha A. Measuring blood pressure from Korotkoff sounds as the brachial cuff inflates on average provides higher values than when the cuff deflates. Physiol Meas 2022; 43. [PMID: 34530413 DOI: 10.1088/1361-6579/ac278f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/16/2021] [Indexed: 11/12/2022]
Abstract
Objective. In this study, we test the hypothesis that if, as demonstrated in a previous study, brachial arteries exhibit hysteresis as the occluding cuff is deflated and fail to open until cuff pressure (CP) is well below true intra-arterial blood pressure (IABP). Approach Estimating systolic (SBP) and diastolic blood pressure (DBP) from the presence of Korotkoff sounds as CPincreasesmay eliminate these errors and give more accurate estimates of SBP relative to IABP readings.Main Results.In 63 subjects of varying age 45.4 ± 19.9 years (range 21-76 years), including 44 men (45.2 ± 19.5, range 21-76 years) and 19 women (45.6 ± 21.4, range 21-75 years), there was a significant (p< 0.0001) increase in SBP from 124.4 ± 15.7 to 129.2 ± 16.3 mmHg and a significant (p< 0.0001) increase in DBP from 70.2 ± 10.7 to 73.6 ± 11.5 mmHg. Of the 63 subjects, 59 showed a positive increase in SBP (1-19 mmHg) and 5 subjects showed a reduction (-5 to -1 mmHg). The average differences for SBP estimates derived as the cuff inflates and estimates derived as the cuff deflates were 4.9 ± 4.7 mmHg, not dissimilar to the differences observed between IABP and NIBP measurements. Although we could not develop multiparameter linear or nonlinear models to explain this phenomenon we have clearly demonstrated through analysis of variance test that both body mass index (BMI) and pulse wave velocity are implicated, supporting the hypothesis that the phenomenon is associated with age, higher BMI and stiffer arteries.Significance. The implications of this study are potentially profound requiring the implementation of a new paradigm for NIBP measurement and a revision of the international standards for their calibration.
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Affiliation(s)
- Branko G Celler
- Biomedical Systems Research Laboratory in the School of Electrical Engineering and Telecommunications, the University of New South Wales, Sydney, NSW 2052, Australia
| | - Ahmadreza Argha
- Graduate School of Biomedical Engineering, the University of New South Wales, Sydney, NSW 2052, Australia
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Meusel M, Wegerich P, Bode B, Stawschenko E, Kusche-Vihrog K, Hellbrück H, Gehring H. Measurement of Blood Pressure by Ultrasound-The Applicability of Devices, Algorithms and a View in Local Hemodynamics. Diagnostics (Basel) 2021; 11:2255. [PMID: 34943492 PMCID: PMC8700406 DOI: 10.3390/diagnostics11122255] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/26/2021] [Accepted: 11/26/2021] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE Due to ongoing technical progress, the ultrasonic measurement of blood pressure (BP) as an alternative to oscillometric measurement (NIBP) or the continuous non-invasive arterial pressure method (CNAP) moves further into focus. The US method offers several advantages over NIBP and CNAP, such as deep tissue penetration and the utilization of different arterial locations. APPROACH Ten healthy subjects (six female, aged 30.9 ± 4.6 years) volunteered in our investigation. In the ultrasonic BP measurement, we differentiated between the directly measured (pulsatile diastolic and systolic vessel diameter) and indirectly calculated variables at three different artery locations on both arms, with two different ultrasound devices in the transversal and longitudinal directions of the transducer. Simultaneously, NIBP monitoring served as reference BP, while CNAP monitored the steady state condition of the arm under investigation. The Moens-Korteweg algorithm (MKE) and the algorithm of the working group of San Diego (SanD) were selected for the indirectly calculated ultrasonic BP data. MAIN RESULTS With US, we were able to measure the BP at each selected arterial position. Due to the investigation setup, we found small but significant interactions of the main effects. Bland and Altman analysis revealed that US-BP measurement was similar to NIBP, with superior accuracy when compared to the established CNAP method. In addition, US-BP measurement showed that the measurement accuracy of both arms can be regarded as identical. In a detailed comparison of the selected arterial vascular sections, systematic discrepancies between the right and left arm could be observed. CONCLUSION In our pilot study, we measured BP effectively and accurately by US using two different devices. Our findings suggest that ultrasonic BP measurement is an adequate alternative for live and continuous hemodynamic monitoring.
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Affiliation(s)
- Moritz Meusel
- Department of Cardiology, Angiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Luebeck, 23538 Luebeck, Germany;
| | - Philipp Wegerich
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Luebeck, 23538 Luebeck, Germany; (P.W.); (B.B.); (E.S.)
- Institute of Biomedical Engineering, University of Luebeck, 23562 Luebeck, Germany
| | - Berit Bode
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Luebeck, 23538 Luebeck, Germany; (P.W.); (B.B.); (E.S.)
| | - Elena Stawschenko
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Luebeck, 23538 Luebeck, Germany; (P.W.); (B.B.); (E.S.)
| | | | - Horst Hellbrück
- Department of Electrical Engineering and Computer Science, Technical University of Applied Sciences Luebeck, 23562 Luebeck, Germany;
| | - Hartmut Gehring
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Center Schleswig-Holstein, Campus Luebeck, 23538 Luebeck, Germany; (P.W.); (B.B.); (E.S.)
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G Celler B, Butlin M, Argha A, Tan I, Yong A, Avolio A. Are Korotkoff Sounds Reliable Markers for Accurate Estimation of Systolic and Diastolic Pressure Using Brachial Cuff Sphygmomanometry? IEEE Trans Biomed Eng 2021; 68:3593-3601. [PMID: 33979277 DOI: 10.1109/tbme.2021.3079578] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
It is well known that non-invasive blood pressure measurements significantly underestimate true systolic blood pressure (SBP), and overestimate diastolic blood pressure (DBP). The aetiology for these errors has not yet been fully established. This study aimed to investigate the accuracy of Korotkoff sounds for detection of SBP and DBP points as used in brachial cuff sphygmomanometry. Brachial cuff pressure and Korotkoff sounds were obtained in 11 patients (6 males: 69.0 ± 6.2 years, 5 females: 71.8 ± 5.5 years) undergoing diagnostic coronary angiography. K2 Korotkoff sounds were obtained by high-pass filtering (>20 Hz) the microphone-recorded signal to eliminate low frequency components. Analysis of the timing of K2 Korotkoff sounds relative to cuff pressure and intra-arterial pressure shows that the onset of K2 Korotkoff sounds reliably detect the start of blood flow under the brachial cuff and their termination, marks the cuff pressure closely coincident with DBP. We have made the critical observation that blood flow under the cuff does not begin when cuff pressure falls just below SBP as is conventionally assumed, and that the delay in the opening of the artery following occlusion, and the consequent delay in the generation of K2 Korotkoff sounds, may lead to significant errors in the determination of SBP of up to 24 mmHg. Our data suggest a potential role of arterial stiffness as a major component of the errors recorded, with underestimation of SBP much more significant for subjects with stiff arteries than for subjects with more compliant arteries.
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Is auscultation an issue when validating 24-h blood pressure monitoring devices? Blood Press Monit 2021; 25:301-302. [PMID: 32675476 DOI: 10.1097/mbp.0000000000000462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Argha A, Celler BG, Lovell NH. Artificial Intelligence Based Blood Pressure Estimation From Auscultatory and Oscillometric Waveforms: A Methodological Review. IEEE Rev Biomed Eng 2020; 15:152-168. [PMID: 33237868 DOI: 10.1109/rbme.2020.3040715] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cardiovascular disease is the number one cause of death globally, with elevated blood pressure (BP) being the single largest risk factor. Hence, BP is an important physiological parameter used as an indicator of cardiovascular health. The use of automated non-invasive blood pressure (NIBP) measurement devices is growing, as measurements can be taken by patients at home. While the oscillometric technique is most common, some automated NIBP measurement methods have been developed based on the auscultatory technique. By utilizing (relatively) large BP data annotated by experts, models can be trained using machine learning and statistical concepts to develop novel NIBP estimation algorithms. Amongst artificial intelligence (AI) techniques, deep learning has received increasing attention in different fields due to its strength in data classification and feature extraction problems. This paper reviews AI-based BP estimation methods with a focus on recent advances in deep learning-based approaches within the field. Various architectures and methodologies proposed todate are discussed to clarify their strengths and weaknesses. Based on the literature reviewed, deep learning brings plausible benefits to the field of BP estimation. We also discuss some limitations which can hinder the widespread adoption of deep learning in the field and suggest frameworks to overcome these challenges.
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