120 Letters to the Editor
Letters to the Editor Blood Pressure Monitoring 2014, 19:120–121
Effect of mechanical behavior of the brachial artery on blood pressure measurement during cuff inflation and cuff deflation
difference between automated inflation blood pressure and manual auscultatory deflation blood pressure to have very small average differences in a full SP10 clinical trial.
Richard A. Darta, Bruce Alpertb and David Quinnc, aCenter for Human Genetics, Marshfield Clinic Research Foundation, Marshfield, Wisconsin, b Department of Cardiology, University of Tennessee Health Science Center, Memphis, Tennessee and cWelch Allyn, Skaneateles Falls, New York, USA
Acknowledgements
Correspondence to Richard A. Dart, MD, Center for Human Genetics, Marshfield Clinic Research Foundation, 1000 N Oak Avenue, Marshfield, WI 54449, USA Tel: + 1 715 389 4011; fax: + 1 715 389 3535; e-mail: [email protected]
Conflicts of interest
There are no conflicts of interest.
References 1
Received 4 November 2013 Accepted 10 December 2013 2
In response to the article by Zheng et al. [1], we wish to draw attention to the following concern: it is desirable to investigate the differences to better understand the role of brachial artery mechanics in the noninvasive measurement of blood pressure. However, readers of this article could easily be led to believe that differences between inflation and deflation signals cause automated inflation devices to have a bias or to be less accurate in the determination of systolic and diastolic pressures: this is simply untrue. The experimentation described in the article applies the same generic oscillometric fixed ratios to inflation and deflation data, which is not representative of inflation devices on the market today. As a general rule, generic fixed oscillometric ratios yield inaccurate results. Most manufacturers of automated devices have moved to more sophisticated algorithms. Furthermore, algorithms that determine systolic, diastolic, and mean arterial pressure from the inflation phase of the noninvasive blood pressure (NIBP) cycle need to process the data differently than deflation algorithms to obtain accurate systolic, diastolic, and mean arterial pressure from the inflation phase of the NIBP cycle determinations. Therefore, differences noted in the application of the same algorithm rules to both inflation and deflation data should not be considered an indication of inaccuracy of inflation devices. All of the inflation devices marketed in the USA have been, or should have been, validated against standard auscultatory deflation readings or intraarterial reference readings. The authors’ claim that ‘ythere are no clinical studies available on the effect of cuff inflation in comparison with the traditional deflation technique’ is incorrect. The 2007 article by Dr Bruce Alpert [2] describes the clinical results of a comparison between an inflation NIBP system and a traditional deflation reference algorithm for automated blood pressure measurement. This study showed the
Zheng D, Pan R, Murray A. Effect of mechanical behaviour of the brachial artery on blood pressure measurement during both cuff inflation and cuff deflation. Blood Press Monit 2013; 18:265–271. Alpert BS. Clinical evaluation of the Welch Allyn SureBP algorithm for automated blood pressure measurement. Blood Press Monit 2007; 12:215–218. DOI: 10.1097/MBP.0000000000000023
In response: Confirmation of the need to evaluate devices that measure blood pressure during cuff inflation with manual measurements during normal deflation Dingchang Zhenga, Fan Pana,b and Alan Murraya, aCardiovascular Physics and Engineering Research Group, Institute of Cellular Medicine, Newcastle University, Royal Victoria Infirmary, Newcastle upon Tyne, UK and bDigital Signal Processing Lab, College of Electronics and Information Engineering, Sichuan University, Chengdu, Sichuan, People’s Republic of China Correspondence to Dingchang Zheng, PhD, Cardiovascular Physics and Engineering Research Group, Institute of Cellular Medicine, Newcastle University, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, UK Tel: + 44 191 2823813; fax: + 44 191 2130290; e-mail: [email protected] Received 27 November 2013 Accepted 10 December 2013
It has been commented that our findings of differences in measured blood pressures (BPs) between cuff inflation and deflation could lead readers to believe that automated inflation devices are less accurate. We think that unlikely. The aim of our study was purely to investigate the physiological effect of different mechanical behaviour of the brachial artery on BP measurements during cuff inflation and deflation [1]. We made no comment on the accuracy of inflation devices. In fact, we stated in our discussion that ‘When validating automated BP devices, the reference BPs are from manual auscultatory BPs taken during cuff deflation, as required by the international standards’. This is exactly what these authors and other researchers have done [2–5].
Acknowledgements The authors acknowledge the funding support from the Engineering and Physical Sciences Research Council (EPSRC).
c 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins 1359-5237
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Letters to the Editor Blood Pressure Monitoring 2014, 19:120–121
Effect of mechanical behavior of the brachial artery on blood pressure measurement during cuff inflation and cuff deflation
difference between automated inflation blood pressure and manual auscultatory deflation blood pressure to have very small average differences in a full SP10 clinical trial.
Richard A. Darta, Bruce Alpertb and David Quinnc, aCenter for Human Genetics, Marshfield Clinic Research Foundation, Marshfield, Wisconsin, b Department of Cardiology, University of Tennessee Health Science Center, Memphis, Tennessee and cWelch Allyn, Skaneateles Falls, New York, USA
Acknowledgements
Correspondence to Richard A. Dart, MD, Center for Human Genetics, Marshfield Clinic Research Foundation, 1000 N Oak Avenue, Marshfield, WI 54449, USA Tel: + 1 715 389 4011; fax: + 1 715 389 3535; e-mail: [email protected]
Conflicts of interest
There are no conflicts of interest.
References 1
Received 4 November 2013 Accepted 10 December 2013 2
In response to the article by Zheng et al. [1], we wish to draw attention to the following concern: it is desirable to investigate the differences to better understand the role of brachial artery mechanics in the noninvasive measurement of blood pressure. However, readers of this article could easily be led to believe that differences between inflation and deflation signals cause automated inflation devices to have a bias or to be less accurate in the determination of systolic and diastolic pressures: this is simply untrue. The experimentation described in the article applies the same generic oscillometric fixed ratios to inflation and deflation data, which is not representative of inflation devices on the market today. As a general rule, generic fixed oscillometric ratios yield inaccurate results. Most manufacturers of automated devices have moved to more sophisticated algorithms. Furthermore, algorithms that determine systolic, diastolic, and mean arterial pressure from the inflation phase of the noninvasive blood pressure (NIBP) cycle need to process the data differently than deflation algorithms to obtain accurate systolic, diastolic, and mean arterial pressure from the inflation phase of the NIBP cycle determinations. Therefore, differences noted in the application of the same algorithm rules to both inflation and deflation data should not be considered an indication of inaccuracy of inflation devices. All of the inflation devices marketed in the USA have been, or should have been, validated against standard auscultatory deflation readings or intraarterial reference readings. The authors’ claim that ‘ythere are no clinical studies available on the effect of cuff inflation in comparison with the traditional deflation technique’ is incorrect. The 2007 article by Dr Bruce Alpert [2] describes the clinical results of a comparison between an inflation NIBP system and a traditional deflation reference algorithm for automated blood pressure measurement. This study showed the
Zheng D, Pan R, Murray A. Effect of mechanical behaviour of the brachial artery on blood pressure measurement during both cuff inflation and cuff deflation. Blood Press Monit 2013; 18:265–271. Alpert BS. Clinical evaluation of the Welch Allyn SureBP algorithm for automated blood pressure measurement. Blood Press Monit 2007; 12:215–218. DOI: 10.1097/MBP.0000000000000023
In response: Confirmation of the need to evaluate devices that measure blood pressure during cuff inflation with manual measurements during normal deflation Dingchang Zhenga, Fan Pana,b and Alan Murraya, aCardiovascular Physics and Engineering Research Group, Institute of Cellular Medicine, Newcastle University, Royal Victoria Infirmary, Newcastle upon Tyne, UK and bDigital Signal Processing Lab, College of Electronics and Information Engineering, Sichuan University, Chengdu, Sichuan, People’s Republic of China Correspondence to Dingchang Zheng, PhD, Cardiovascular Physics and Engineering Research Group, Institute of Cellular Medicine, Newcastle University, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, UK Tel: + 44 191 2823813; fax: + 44 191 2130290; e-mail: [email protected] Received 27 November 2013 Accepted 10 December 2013
It has been commented that our findings of differences in measured blood pressures (BPs) between cuff inflation and deflation could lead readers to believe that automated inflation devices are less accurate. We think that unlikely. The aim of our study was purely to investigate the physiological effect of different mechanical behaviour of the brachial artery on BP measurements during cuff inflation and deflation [1]. We made no comment on the accuracy of inflation devices. In fact, we stated in our discussion that ‘When validating automated BP devices, the reference BPs are from manual auscultatory BPs taken during cuff deflation, as required by the international standards’. This is exactly what these authors and other researchers have done [2–5].
Acknowledgements The authors acknowledge the funding support from the Engineering and Physical Sciences Research Council (EPSRC).
c 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins 1359-5237
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
