Can a simulator that regenerates physiological waveforms evaluate oscillometric non-invasive blood pressure devices?
Department of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, UK, and Department of Biomedical Engineering, ESIL, Université de la Méditerranée, Aix-Marseille II, France. Blood Pressure Monitoring
(Impact Factor: 1.53).
05/2006; 11(2):63-7. DOI: 10.1097/01.mbp.0000200482.72410.e2
A simulator has been developed that enables previously recorded clinical oscillometric waveforms to be regenerated for testing oscillometric non-invasive blood pressure measurement devices. Two non-invasive blood pressure devices were evaluated using the simulator with its database of 243 waveforms, to assess the value of a simulator for such evaluations.
Two oscillometric non-invasive blood pressure devices, both of which had previously been validated against auscultatory references, were selected. The Omron HEM-907 (Omron, Hoofddorp, The Netherlands) measures the pressure during linear cuff deflation and the GE ProCare 400 (GE Healthcare, Tampa, Florida, USA) measures during step deflation. Each non-invasive blood pressure device was attached to the simulator and pressures were recorded from all 243 waveforms. The differences between the systolic and diastolic pressures measured by each non-invasive blood pressure device and the auscultatory references for each waveform were calculated. These were assessed with the European and American validation standards and with the British Hypertension Society protocol.
The paired pressure differences (non-invasive blood pressure device minus auscultatory reference) for each device complied partly, but not fully, with the standards or protocol. The means (+/-standard deviation) of the paired systolic and diastolic pressures differences for the Omron were -2.4 mmHg (+/-5.9 mmHg) and -8.9 mmHg (+/-6.5 mmHg), and for the ProCare were -6.5 mmHg (+/-10.4 mmHg) and -2.9 mmHg (+/-7.0 mmHg), respectively. The pressures recorded by the Omron device met the standards for systolic pressures but failed for diastolic pressures and conversely for the ProCare.
This represents the first evaluation of non-invasive blood pressure devices with a simulator that generates previously recorded clinical oscillometric waveforms. It allowed data from over 100 study participants to be used. Both devices had been previously clinically validated, but their evaluation using the simulator with its regenerated waveforms only partly met the required criteria. Although the results did not fully match previous clinical validations, these initial results give encouragement that a simulator with sufficient stored waveforms might be able to replace the difficult and expensive clinical evaluation of non-invasive blood pressure devices that has prevented many devices from being fully evaluated.
Available from: Chengyu Liu
- "A BP simulator, designed and construcsted at the Physikalisch-Technische Bundesanstalt (PTB) and capable of generating previously recorded oscillometric wavfroms  , was used to regenerate the 40 oscillometric waveforms. It has been reported that this BP simulator could reliably regenerate unstable physiological oscillometric waveforms . "
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ABSTRACT: Non-invasive blood pressure (NIBP) devices are widely used by the geneal public. The device validation required by the international standards is performed under resting conditon. However, NIBPs are often used without giving too much consideration about the measurement condtions. This study aimed to provide scientific evidence for the inapporiate use of BP devices under unstable conditions.
BP measurements were performed on 20 healthy subjects under both resting and regular deep breathing conditions. During the measurement the oscillometric cuff pressure waveforms were recorded digitally at a recommended deflation rate of 2-3 mmHg/s. They were then regenerated by a specially designed BP simulator and presented to two clinically validated hospital grade automatic NIBP devices to obtain automated BPs. Automed SBP and DBP from both resting and regular deep breathing conditions were finally compared between the two devices.
Under resting condition, there was no significant difference in both automated SBP and DBP between the two devices (mean±SD: 119.1±10.1 vs 118.9±10.6 mmHg for SBP; 72.2±8.5 vs 71.2±8.8 mmHg for DBP). However, under regular deep breathing condition, significant SBP and DBP differences were observed between the two devices (both P<0.01; mean±SD: 118.8±10.6 vs 115.1±11.6 mmHg for SBP; 68.5±8.6 vs 65.3±8.9 mmHg for DBP). Furthermore, we expected that deep breathing would decrease both SBP and DBP. However, the auto SBP decrease induced by deep breathing was not observed from device 1 (P=0.6), and the auto DBP decrease was significantly different between the two devices (P<0.01, with a mean difference±SD of 3.1±5.8 mmHg), indicating the inconsistent measurements between the two devices under unstable conditions.
Our results provided scientifc evidence that automated BP devices can only be used under the condition from which the validation is performed, and also confirmed that a seperate validation should be perfomed in order for the devices to be used under different conditions.
Computing in Cardiology, Nice, France; 11/2015
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ABSTRACT: Peripheral pulses have been recorded and analysed to determine the accuracy with which pulse transit times (PTTs) can be measured. Measurements of PTT between the ECG Q-wave and various peripheral sites were made in 10 normal subjects on 10 separate days. Mean values were determined for the ears (174 ms), fingers (245 ms), and toes (361 ms). The technique was sufficiently accurate to detect small changes in PTT due to changes in posture; sitting to lying, 5.2 ms. When comparing simultaneous measurements on bilateral sites only small differences in PTT were discovered, and these were not significant in the study group as a whole. However, these differences were significant in some individuals. When the subjects raised a single arm or leg, significant differences (38 ms and 49 ms respectively) were recorded between sides. The day-to-day repeatability sigma (expressed as the square root of the within-subject mean square variance) of individual PTT measurements on a subject (supine) was for ears, fingers and toes respectively 9.4, 9.2 and 12 ms. For right-left differences the repeatability was 7.2, 5.9 and 14 ms. Hence changes in PTTs, or differences between right and left sides, can be detected from single measurements with 95% confidence if they exceed approximately 20 ms in ears or fingers and 30 ms in toes.
Clinical Physics and Physiological Measurement 12/1988; 9(4):319-30. DOI:10.1088/0143-0815/9/4/003
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ABSTRACT: Unless users of oscillometric noninvasive blood pressure simulators understand both the indirect nature of the oscillometric method and its empirical implementation, they can misunderstand the performances of both noninvasive blood pressure devices and simulators. The article describes the variation in the oscillometric pulses with cuff pressure, leading to an overview of the characteristics, limitations, and applications of simulators. The differences between pressures recorded by noninvasive blood pressure devices and simulator settings are explained, emphasizing that unless the simulator uses physiologic oscillometric envelopes, the differences do not necessarily imply lack of calibration of noninvasive blood pressure device or simulator. Simulator functional specifications are described, advocating that simulators include physiologic oscillometric envelopes and pulse waveforms.
Journal of clinical engineering 04/2006; 31(2):85-95. DOI:10.1097/00004669-200604000-00026
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