Surgery – Diagnostic testing – Cardiovascular
Patent
1998-04-06
1999-03-16
Nasser, Robert L.
Surgery
Diagnostic testing
Cardiovascular
600490, 600500, A61B 500
Patent
active
058823115
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to the measurement of peripheral blood pressure pulse waveforms and the use of these waveforms to determine pulse waveforms at other sites. More particular, it is concerned with the calibration of these waveforms.
BACKGROUND ART
A technique for utilising peripheral pressure pulses to determine the pulse waveform at other body sites, particularly the ascending aortic waveform, is disclosed in U.S. Pat. No. 5,265,011 by Michael F. O'Rourke. The books "The Arterial Pulse" by O'Rourke, Kelly and Avolio published by Lea Febiger, Philadelphia USA 1992 and "Arterial Vasodilation", by O'Rourke, Saffer, and Dzau, published by Arnold, London 1993 disclose the use of a measured peripheral waveform to determine the waveform at another site, using an empirically determined transfer function. The derived waveform can be calibrated, as it is derived from the peripheral waveform which itself is calibrated. In these documents, it is assumed that the brachial cuff sphygmomanometer measurement can be used to directly calibrate waveforms measured at the radial artery. It is assumed that relatively little change occurs in the parameters between the brachial artery and the radial artery. Whilst this is a reasonable working assumption, it is not strictly accurate.
It is an object of the present invention to provide an improved calibration procedure, such that derived waveforms are able to be more accurately calibrated.
SUMMARY OF INVENTION
According to a first aspect, the present invention provides a method of calibrating a derived pressure pulse waveform, said derived waveform being determined by processing a peripherally measured waveform, comprising the steps of:
1. measuring at a first site a blood pressure pulse waveform;
2. measuring substantially simultaneously using a calibrated instrument the systolic and diastolic pressures at a second site;
3. determining the pulse waveform shape at said second site from the waveform measured at said first site using a first predetermined transfer function;
4. calibrating the waveform at said second site using the measured systolic and diastolic pressures;
5. determining the pulse waveform shape at a third site directly or indirectly from the waveform measured at said first site using a second predetermined transfer function;
6. calibrating the waveform at said third site directly or indirectly from the calibrated waveform from said second site.
Preferably, the measurements at the first and second sites are performed non-invasively. The first site may be, conveniently, the radial artery or the finger, and the second site may be the brachial artery, although any convenient site may be chosen.
It will be appreciated that the present invention is not limited to the steps being performed in the particular order shown above. The three different transfer functions mentioned above may in fact be only two different transfer functions, depending upon how the calculation is desired to be performed. The user is only required, in any case, to measure the waveform, and make a calibration measurement. For example, the measured waveform at the first site may be used to derive an uncalibrated waveform at the second site, which is then calibrated by measurement at that site. The calibrated waveform may then be used to calibrate the waveform at the first site. From the calibrated second site waveform, a calibrated waveform at the third site can be directly obtained by applying the appropriate transfer function.
It will be understood that the calculation process may actually be performed in a number of equivalent ways. However, the general principle of the present invention is retained--that is, that a measurement at one site is used to provide calibration for the derived waveform, and at a second site a waveform is acquired for calculating the derived waveform, with different transfer functions being used between the first and second sites to the site for which the derived waveform is required.
The measurement steps may be performed with manually ope
REFERENCES:
patent: 4873987 (1989-10-01), Djordjevich et al.
patent: 4907596 (1990-03-01), Schmid et al.
patent: 5101828 (1992-04-01), Welkowitz et al.
patent: 5241964 (1993-09-01), McQuilkin
patent: 5269310 (1993-12-01), Jones et al.
patent: 5746698 (1998-05-01), Bos et al.
patent: 5785659 (1998-07-01), Caro et al.
Nasser Robert L.
PWV Medical Pty Ltd.
LandOfFree
Calibration for blood pressure pulses does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Calibration for blood pressure pulses, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Calibration for blood pressure pulses will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-812608