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Automatic blood pressure measurement: the oscillometric waveform shape is a potential contributor to differences between oscillometric and auscultatory pressure measurements

Amoore, John Na; Lemesre, Yannb; Murray, Ian Cc; Mieke, Stephand; King, Susan Te; Smith, Fiona Ee; Murray, Alane

Journal of Hypertension:
doi: 10.1097/HJH.0b013e3282f06ec7
Original papers: Blood pressure measurements
Abstract

Objective: To explore the differences between oscillometric and auscultatory measurements.

Method: From a simulator evaluation of a non-invasive blood pressure (NIBP) device regenerating 242 oscillometric blood pressure waveforms from 124 subjects, 10 waveforms were selected based on the differences between the NIBP (oscillometric) and auscultatory pressure measurements. Two waveforms were selected for each of five criteria: systolic over and underestimation; diastolic over and underestimation; and close agreement for both systolic and diastolic pressures. The 10 waveforms were presented to seven different devices and the oscillometric–auscultatory pressure differences were compared between devices and with the oscillometric waveform shapes.

Results: Consistent patterns of waveform-dependent over and underestimation of systolic and diastolic pressures were shown for all seven devices. The mean and standard deviation, for all devices, of oscillometric–auscultatory pressure differences were: for the systolic overestimated waveforms, 36 ± 28/−6 ± 3 and 23 ± 2/−1 ± 3 mmHg (systolic/diastolic differences); for systolic underestimated waveforms, −21 ± 5/−4 ± 3 and −11 ± 4/−3 ± 3 mmHg; for diastolic overestimated waveforms, 3 ± 4/12 ± 5 and 17 ± 6/10 ± 2 mmHg; for diastolic underestimated waveforms, 1 ± 4/−22 ± 4 and −9 ± 6/−29 ± 4 mmHg; and for the two waveforms with good agreement, 0 ± 6/0 ± 3 and −2 ± 4/−4 ± 3 mmHg. Waveforms for which devices showed good oscillometric and auscultatory agreement had smooth envelopes with clearly defined peaks, compared with the broader plateau and complex shapes of those waveforms for which devices over or underestimated pressures.

Conclusion: By increasing the understanding of the characteristics and limitations of the oscillometric method and the effects of waveform shape on pressure measurements, simulator evaluation should lead to improvements in NIBP devices.

Author Information

aDepartment of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, UK

bDepartment of Biomedical Engineering, ESIL, Université de la Méditerranée, Aix-Marseille II, France

cDepartment of Medical Physics, University of Edinburgh, Edinburgh, UK

dPhysiklisch-Technische Bundesanstalt, Berlin, Germany

eDepartment of Medical Physics, Freeman Hospital, Newcastle University, Newcastle upon Tyne, UK

Received 2 April, 2007

Revised 23 July, 2007

Accepted 26 July, 2007

Correspondence to John Amoore, Department of Medical Physics, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, UK Tel: +44 0131 242 2351; fax: +44 0131 242 2378; e-mail: john.amoore@luht.scot.nhs.uk

This work has not previously been presented in whole or in part, nor is it under consideration by any other journal.

© 2008 Lippincott Williams & Wilkins, Inc.