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