US 9,414,755 B2Granted

Method for estimating a central pressure waveform obtained with a blood pressure cuff

AssigneeUSCOM Limited

InventorAndrew Lowe

Life of this patent

Estimating the term…

Loading patent…

Abstract

A physics-based mathematical model is used to estimate central pressure waveforms from measurements of a brachial pressure waveform measured using a supra-systolic cuff. The method has been tested in numerous subjects undergoing cardiac catheterisation. Central pressure agreement was within 11 mm Hg and as good as the published non-invasive blood pressure agreement between the oscillometric device in use and the so-called “gold standard.” It also exceeds international standards for the performance of non-invasive blood pressure measurement devices. The method has a number of advantages including simplicity of application, fast calculation and accuracy of prediction. Additionally, model parameters have physical meaning and can therefore be tuned to individual subjects. Accurate estimation of central waveforms also allow continuous measurement (with intermittent calibration) using other non-invasive sensing systems including photoplethysmography.

Claims33

Dependent claims

A method of sensing and analyzing supra-systolic blood pressure waveforms obtained non-invasively from a brachial artery in an arm of a patient, using a blood pressure cuff and cuff pressure transducer, to estimate central artery blood pressures, said method comprising the steps of:

(a) applying and inflating a blood pressure cuff on the patient's arm to a supra-systolic pressure;
(b) using a non-invasive sensor, sensing a succession supra-systolic cuff pressure waveforms associated with the brachial artery in said patient's arm, each supra-systolic cuff pressure waveform forming a heart-pulse synchronous cuff pressure signal representing at least one cardiac ejection cycle;
(c) using a computer, analyzing the supra-systolic cuff pressure waveforms using a first mathematical model relating the heart-pulse synchronous cuff pressure signal and brachial pressure near the cuff on said patient's arm to produce an estimated brachial pressure signal representing estimated brachial pressure waveforms, wherein the heart-pulse synchronous cuff pressure signal is scaled relative to previously measured systolic and diastolic pressures, such that the amplitude of the estimated brachial pressure signal is a proportion of a difference between the previously measured systolic and diastolic pressures;
(d) using a computer, analyzing the estimated brachial pressure waveforms using a second mathematical model relating the estimated brachial pressure signal and a central pressure at the root of the brachial artery to produce estimated central artery blood pressures and estimated central artery blood pressure waveforms, whereby the second mathematical model includes at least one parameter with physical meaning selected from a group consisting of (a) an impedance relationship at the cuff and (b) a parameter relating a phase of a pressure wave at substantially the subclavian root to a phase of a supra-systolic pressure wave at the occluding cuff;
and
(e) generating a computer output representing estimated central artery blood pressures based on the analysis.

3 more elements

A method analyzing central blood pressure waveforms obtained non-invasively from a brachial artery in an arm of a patient, using a blood pressure cuff and cuff pressure transducer as a first non-invasive sensor and as a second non-invasive sensor of heart synchronous pulse signals, thereby to estimate central artery blood pressures, said method comprising the steps of

(a) applying and inflating a blood pressure cuff on the patient's arm to a supra-systolic pressure;
(b) sensing a first succession of supra-systolic cuff pressure waveforms associated with the brachial artery in said patient's arm using the first non-invasive sensor, each supra-systolic cuff pressure waveform forming a heart-pulse synchronous cuff pressure signal representing at least one cardiac ejection cycle;
(c) using a computer, analyzing the supra-systolic cuff pressure waveforms using a first mathematical model relating the heart-pulse synchronous cuff pressure signal and brachial pressure near the cuff on said patient's arm to produce an estimated brachial pressure signal representing estimated brachial pressure waveforms;
(d) using a computer, analyzing the estimated brachial pressure waveforms using a second mathematical model relating the estimated brachial pressure signal and a central pressure at the root of the brachial artery to produce estimated central artery blood pressures and estimated central artery blood pressure waveforms, whereby the second mathematical model includes at least one parameter with physical meaning selected from a group consisting of (a) an impedance relationship at the cuff and (b) a parameter relating a phase of the pressure wave at substantially the subclavian root to a phase of a supra-systolic pressure wave at the occluding cuff;
(e) sensing a second succession of heart-pulse synchronous cuff pressure signals using the second non-invasive sensor approximately corresponding in time to the first succession of supra-systolic cuff pressure waveforms;
(f) using a computer, calculating a mathematical relationship relating the estimated central artery blood pressures to the second succession of heart-pulse synchronous cuff pressure signals;
(g) deflating the blood pressure cuff to a sub-diastolic pressure;
(h) sensing a third succession of heart-pulse synchronous cuff pressure signals using the second non-invasive sensor;
(i) using a computer, determining the central artery blood pressures by using the previously calculated mathematical relationship relating the estimated central artery blood pressures to the second succession of heart-pulse synchronous cuff pressure signals and to the third succession of heart-pulse synchronous cuff pressure signals from the second non-invasive sensor;
and
(j) generating a computer output representing estimated central artery blood pressures based on the analysis.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/454,123Filed 13 May 2009 · us provisional application
Priority: 24 Sep 2008
Published: US 2009/0287097 A119 Nov 2009
Granted: 16 Aug 2016
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

A61B 5/022
Measuring pressure in heart or blood vessels: by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
A61B 5/02108
Measuring pressure in heart or blood vessels: from analysis of pulse wave characteristics
A61B 5/02225
By applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers: using the oscillometric method
A61B 5/411
Detecting, measuring or recording for evaluating the immune or lymphatic systems: detecting or monitoring allergy or intolerance reactions to an…