U.S. patent application number 13/198000 was filed with the patent office on 2011-11-24 for estimation of pressure at remote site by brachial oscillometric wave from analysis.
This patent application is currently assigned to NATIONAL YANG-MING UNIVERSITY. Invention is credited to CHEN-HUAN CHEN, HAO-MIM CHENG.
Application Number | 20110288422 13/198000 |
Document ID | / |
Family ID | 40340715 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110288422 |
Kind Code |
A1 |
CHEN; CHEN-HUAN ; et
al. |
November 24, 2011 |
ESTIMATION OF PRESSURE AT REMOTE SITE BY BRACHIAL OSCILLOMETRIC
WAVE FROM ANALYSIS
Abstract
The present invention relates to a device and a method for
estimating central systolic blood pressure based on oscillometric
signals from brachial artery by the use of a pressure cuff.
Inventors: |
CHEN; CHEN-HUAN; (TAIPEI
CITY, TW) ; CHENG; HAO-MIM; (TAIPEI CITY,
TW) |
Assignee: |
NATIONAL YANG-MING
UNIVERSITY
TAIPEI CITY
TW
|
Family ID: |
40340715 |
Appl. No.: |
13/198000 |
Filed: |
August 4, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12132826 |
Jun 4, 2008 |
|
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13198000 |
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Current U.S.
Class: |
600/486 ;
600/494 |
Current CPC
Class: |
A61B 5/02116 20130101;
A61B 5/022 20130101; A61B 5/02225 20130101 |
Class at
Publication: |
600/486 ;
600/494 |
International
Class: |
A61B 5/0215 20060101
A61B005/0215; A61B 5/025 20060101 A61B005/025 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 2007 |
TW |
096147043 |
Claims
1. A method of estimating the central arterial blood pressure by
measuring the signal of pulse oscillation of the brachium artery by
cuff, which includes: (1) detecting the oscillometric waveform in
the cuff; (2) adjusting the oscillometric waveform by the average
blood pressure and diastolic blood pressure measured by the cuff to
calculate (I) systolic blood pressure of pulse volume recording,
(II) last phase systolic blood pressure of pulse volume recording,
(III) the value of the area below the waveform during systole and
the area below the waveform during diastole dividing the area below
the waveform during diastole, and (IV) the pressure of reflected
wave hiding beneath the waveform of pressure; and (3) bringing
factor (I).about.(IV) to a formula, a regression formula, to
measure the measured central arterial blood pressure, and serving
the measured central arterial blood pressure as dependent
variables; the factors (I).about.(IV) in Step (2) as independent
variables, and then to solve the formula.
2. The method of claim 1, wherein the measured central arterial
blood pressure is obtained by invasive procedures.
3. The method of claim 1, wherein the central artery is a carotid
artery or ascending aorta.
4. The method of claim 1, wherein the detection of the
oscillometric waveform in the cuff of Step (1) includes the process
of pressure decreasing in the cuff, the moment of the pressure in
the cuff decreasing to a certain degree, and the oscillometric
signal recorded during the process of the pressure re-increasing in
the cuff.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional application of the pending
U.S. patent application Ser. No. 12/132,826 filed on Jun. 4, 2008,
all of which is hereby incorporated by reference in its entirety.
Although incorporated by reference in its entirety, no arguments or
disclaimers made in the parent application apply to this divisional
application. Any disclaimer that may have occurred during the
prosecution of the above-referenced application(s) is hereby
expressly rescinded. Consequently, the Patent Office is asked to
review the new set of claims in view of the entire prior art of
record and any search that the Office deems appropriate.
FIELD OF THE INVENTION
[0002] The present invention relates to a method that dynamically
analyzes the form of pressure wave in cuff recorded during
measurement of blood pressure by electronic manometer. The analytic
method measures the central arterial systolic blood pressure
accurately, and the manometer employing the technology of the
present invention can simultaneously measure the traditional
peripheral arterial (brachium artery) blood pressure as well as the
central arterial blood pressure. The present invention largely
improves the accuracy of hypertensive medicine choice and the
dosage adjustment.
BACKGROUND OF THE INVENTION
[0003] Abnormality of blood dynamics is usually occurred in
hypertension, including enhancement of reflected wave, acceleration
of pulse conduction and decrease of compliance. It has been
clinically proven that the central arterial pressure is a key
factor of recovery from hypertension. The brachium arterial blood
pressure value is determined by measurement of the peripheral
arterial blood pressure by traditional or electronic manometer,
usually being higher than the central arterial blood pressure, such
as the ascending aortic and carotid arterial blood pressure value.
Due to the different effects of different medications of blood
pressure-lowering medicine on the central aortic and peripheral
arterial blood pressure, using the brachium arterial systolic and
diastolic blood pressure measured alone by traditional or
electronic manometer to estimate the central aortic blood pressure
may overestimate or underestimate the effect of blood
pressure-lowering medicine on the central aortic blood pressure.
Hence, it is insufficient to evaluate how well the blood pressure
is controlled only by measuring of the brachium arterial blood
pressure. There has been a method already which can estimate the
waveform and value of ascending aortic systolic blood pressure by
recording the radial arterial waveform, the brachium arterial blood
pressure, and by a known mathematic formula, the related
commercialized product (SphygmoCor, AtCor Medical Pty Limited) has
been widely used in clinical trial, and it has been proven that the
estimation of the value of ascending aortic systolic blood pressure
can show the different effects on the central aortic blood pressure
by different medications of blood pressure-lowering medicine. It
could predict the risk of patients with cardiovascular disease
after medication of different pressure-lowering medicines; hence,
the measurement of the central arterial blood pressure played a
role in the control of hypertension. Although SphygmoCor can
estimate the ascending aortic systolic blood pressure, it needs
expensive and complicated accessories and special operation
techniques and is not appropriate for widely use in hospital and
personal use of a patient.
[0004] Patent No. WO/1996/0390 showed an innovation of technology,
employing two separated measurement parts (upper arm and wrist) to
measure the brachium arterial blood pressure value (by technology
of common electronic manometer) and the radial arterial blood
pressure waveform (by pen-shaped arterial tonometer) respectively,
and then converts the radial arterial blood pressure waveform to
the ascending aortic blood pressure waveform by a known mathematic
formula, and adjusts the converted ascending aortic blood pressure
waveform by the measured brachium arterial blood pressure value.
Users can obtain the ascending aortic blood pressure value through
the converted ascending aortic blood pressure waveform, which is
the commercialized, non-invasive and patented technology of
estimating the waveform and value of ascending aortic blood
pressure. The product of this patent, invented by an Australian
scientist, Dr. Michael F. O'Rourke, needs the expensive pen-shaped
pressure tonometer, a laptop, and a specialized analytic program.
The pen-shaped pressure tonometer is related to the accuracy of the
estimated value and needs special operation technique; therefore,
the usage of the expensive diagnostic instrument is still limited
to research and can not be a personal home care.
SUMMARY OF THE INVENTION
[0005] The present invention provides a measuring device of
estimating the central arterial blood pressure at remote site (10),
which includes: [0006] (1) a controlling device (20) of the
pressure change in the cuff, which is used to control the process
of pressurization, decompression or maintenance a certain pressure
value; [0007] (2) a recording and saving device (30) of
oscillometric signals of the pressure in the cuff; and [0008] (3)
an analytic device (40) of analyzing the oscillometric signals of
the pressure in the cuff, which is used to estimate the central
arterial blood pressure by real-time analysis of the oscillometric
signals of the pressure.
[0009] The present invention further provides a method of
estimating the central arterial blood pressure by measuring the
signal of pulse oscillation of the brachium artery by cuff, which
includes: [0010] (1) detecting the oscillometric waveform in the
cuff; [0011] (2) adjusting the oscillometric waveform by the
average blood pressure and diastolic blood pressure measured by the
cuff to calculate (I) systolic blood pressure of pulse volume
recording, (II) last phase systolic blood pressure of pulse volume
recording, (III) the value of the area below the waveform during
systole and the area below the waveform during diastole dividing
the area below the waveform during diastole, and (IV) the pressure
of reflected wave hiding beneath the waveform of pressure; and
[0012] (3) Bringing factors (I).about.(IV) to a formula, a
regression formula, to measure the measured central arterial blood
pressure, and serving the measured central arterial blood pressure
as a dependent variable; the factors (I).about.(IV) in Step (2) as
independent variable, and then to solve the formula.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention changes the procedure of measuring
blood pressure appropriately, and uses the recorded oscillatory
wave of pressure pulse in the cuff to do dynamic analysis and then
estimates the central aortic systolic blood pressure accurately.
The techniques of operation and analysis of the present invention
can apply to a common electronic manometer without other expensive
accessories. The diagnosis of hypertension can be a revolution
while a common electronic manometer has the function to measure the
central aortic systolic blood pressure.
[0014] The present invention relates to a method of analyzing the
oscillatory wave of pressure pulse in the cuff. The present
invention use the pressure value obtained from the measurement part
(upper arm) to estimate the pressure value of remote parts
(ascending aorta or carotid arteries) directly. In detail, the
present invention is characterized by the analytic method of
oscillatory waveform of pressure pulse used in the cuff of
electronic manometer, including the analysis of dynamic oscillatory
waveform (the oscillatory waveform recorded during decrease period
of pressure in the cuff) and the analysis of static oscillatory
waveform (the oscillatory waveform recorded when the pressure in
the cuff decreased to certain degree, the so-called pulse volume
recording). The analytic method of the present invention includes
the techniques of analyzing time and frequency, which estimates the
pressure value of remote parts (ascending aorta or carotid
arteries) directly through real-time analysis oscillatory waveform
of pressure pulse.
[0015] As Shown in FIG. 1 A, the present invention employs a
measurement part (cuff) as same as the one in a common electronic
manometer and a special measurement device to measure the brachium
arterial blood pressure value (by the technique of common pulse
oscillatory electronic manometer) and record the oscillatory
pressure waveform in the cuff under different pressure control
(saved temporarily in dynamic memory chip) spontaneously, and then
analyzes the oscillatory pressure waveform immediately by a
controlling chip and estimate the central arterial (ascending
aortic or carotid arterial) systolic blood pressure value. The new
developed electronic manometer employed the technology of the
present invention does not need any additional pressure recorder or
laptop except a controlling chip and a dynamic memory chip, and the
operation is as same as the one of a common electronic manometer;
hence, The new developed electronic manometer can be used in
hospital or personal home care.
[0016] The "central artery" refers to carotid arteries or the
ascending aorta.
[0017] As shown in FIG. 1 B, the present invention provides a
measuring device of estimating the central arterial blood pressure
at remote site (10), which includes: [0018] (1) a controlling
device (20) of the pressure change in the cuff, which is used to
control the process of pressurization, decompression or maintaining
a certain pressure value; [0019] (2) a recording and saving device
(30) of oscillometric signals of the pressure in the cuff; and
[0020] (3) an analytic device (40) of analyzing the oscillometric
signals of the pressure in the cuff, which is used to estimate the
central arterial blood pressure by real-time analysis of the
oscillometric signals of the pressure.
[0021] Within the measuring device (10) of the present invention,
the analytic device (40) can calculate the value of systolic blood
pressure, diastolic blood pressure, average pressure, and heart
rate. In an embodiment, the recording and saving device (30) can
record and save the oscillometric waveform of the pressure in the
cuff, which includes the signal of dynamic oscillometric waveform
(recorded during decrease period of pressure in the cuff) and
signal of static oscillometric waveform (recorded when the pressure
in the cuff decreased to certain degree), wherein the static
oscillometric waveform is the so-called pulse volume recording.
[0022] The present invention further provides a method of
estimating the central arterial blood pressure by measuring the
signal of pulse oscillation of the brachium artery by cuff, which
includes: [0023] (1) detecting the oscillometric waveform in the
cuff; [0024] (2) adjusting the oscillometric waveform by the
average blood pressure and diastolic blood pressure measured by the
cuff to calculate (I) systolic blood pressure of pulse volume
recording, (II) last phase systolic blood pressure of pulse volume
recording, (III) the value of the area below the waveform during
systole and the area below the waveform during diastole dividing
the area below the waveform during diastole, and (IV) the pressure
of reflected wave hiding beneath the waveform of pressure; and
[0025] (3) bringing factors (I).about.(IV) to a formula, a
regression formula, to measure the measured central arterial blood
pressure, and serve the measured central arterial blood pressure as
dependent variable; the factor (I).about.(IV) in Step (2) as
independent variable, and then to solve the formula.
[0026] As shown in FIG. 2, the method of the present invention
apply the formula, with known parameters, systolic pressure of
pulse volume recording, last phase systolic blood pressure of pulse
volume recording, the value of the area below the waveform during
systole and the area below the waveform during diastole dividing
the area below the waveform during diastole, the pressure of
reflected wave hiding beneath the waveform of pressure, the heart
rate, and the pressure of the reflected pressure, to calculate the
central arterial systolic blood pressure.
[0027] In an embodiment of the present invention, the measurement
of the oscillometric waveform of the pressure in the cuff includes
the process of pressure decreasing in the cuff, the moment of the
pressure in the cuff decreasing to a certain degree (for example,
60 mmHg) for a certain period, and the oscillometric signal
recorded during the process of the pressure re-increasing in the
cuff.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 A shows the concept of the present invention, wherein
1 is the oscillometric waveform of the brachium artery pulse, 2 is
the waveform of the central arterial blood pressure, and the black
circle is the systolic central arterial blood pressure.
[0029] FIG. 1 B depicts the image of the present invention, wherein
10 is the device of the present invention, 20 is the controlling
device of the pressure change in the cuff, 30 is the recording and
saving device of oscillometric signals of the pressure in the cuff,
and 40 is the analytic device of analyzing the oscillometric
signals of the pressure in the cuff.
[0030] FIG. 2 depicts the diagram of the brachium artery pulse
volume recording of the method of the present invention, wherein
PVR SBP is abbreviated form "pulse volume recording of systolic
blood pressure"; PVR DBP is abbreviated form "pulse volume
recording of diastolic blood pressure"; the incisura is the last
phase systolic blood pressure of pulse volume recording; As is the
area below the waveform during systole; Ad is the area below the
waveform during diastole; and PVR SBP2 is the reflected wave
pressure pulse recorded during pulse volume recording.
[0031] FIG. 3 shows several different waveforms recorded in Example
1, wherein the dotted is the waveform of the brachium arterial
systolic blood pressure; the black is the waveform of the ascending
aortic systolic blood pressure; the gray is the waveform of pulse
volume recording; and the vertical dotted line refers to the time
point of reflected wave pressure.
[0032] FIG. 4 shows the result of Example 1.
[0033] FIG. 5 shows the result of Example 2.
EXAMPLES
Example 1
Invasive Procedures
[0034] 50 experimenters participated in this experiment. After
completion of routine catheterization, a micromanometer-tipped
catheter (model SPC-320, Millar Instruments Inc) placed within the
lumen of a standard 7F Judkins coronary artery catheter was
advanced in the ascending aorta from right radial artery. The
central aortic pressure waveform was recorded simultaneously with
the noninvasive pulse volume recording. The recording was repeated
during hemodynamic transient: at the peak response of intravenous
bolus of 200 ug nitroglycerin. Once the signals had obtained by
micromanometer in ascending aorta were recorded, the catheter was
pulled back, leaving the micromanometer tip in the right brachial
artery beneath the pressure cuff for the brachial pulse volume
recording. Again, the invasive brachial pressure waveforms and the
noninvasive brachial pulse volume traces were recorded
simultaneously. The invasive central aortic and brachial pressure
signals were digitized at a rate of 500 Hz on an IBM-compatible
personal computer and saved for off-line analysis. The pulse volume
recording was performed using the same device and technique as
described in the first year project. The result was shown in FIG.
3.
Data Analysis
[0035] The digitized signals were analyzed using custom software
written in our laboratory. Two to 10 consecutive beats of the
carotid arterial pressure waves, brachial pulse volume traces, and
radial artery pressure waves were signal averaged. Premature beats
and beats immediately after premature beats were excluded. The
signal-averaged carotid and radial arterial pressure wave and
brachial pulse volume recording were calibrated by matching the
mean and diastolic blood pressures of brachial artery pressure
measured by the automated oscillometric sphygmomanometer
incorporated in the device. The peak and lowest value of pressure
waves and brachial pulse volume traces were recorded as systolic
blood pressure and diastolic blood pressure, respectively.
Waveforms were phase aligned, and point-by-point differences and
regressions were used to compare waves. Overall agreement between
the brachial pulse volume recording, carotid, radial, and
reconstructed aortic pressure waveforms were quantified by the sum
of squares of these differences normalized to the number of data
points. Comparisons were examined by linear regression analysis
with calibrated carotid artery pressures or reconstructed central
aortic pressures as the dependent variables. In addition, frequency
domain analysis for waveforms were performed by Fourier transformed
and difference between waveforms less than 20 Hz were compared. The
discrete Fourier transform of the time-averaged waves was evaluated
by a commercial software package (routine fft.m in Matlab, version
4.2, The MathWorks) to yield the modulus and phase angle up to the
20th harmonic. The power spectral densities of the two spectra were
calculated as the squared modulus values for each harmonic. The
spectrum of the brachial PVR and radial tonometry were normalized
to that of the carotid pressure wave by equating the total power of
the two spectra. The transfer function between different pressure
waves was then evaluated by both the differences and ratios of the
moduli and by differences of the phase angles. The result was shown
in FIG. 3.
Prediction of Central Systolic Blood Pressure by Statistical
Regression Equation of Systolic Blood Pressure Estimated from
Calibrated Brachial Pulse Volume Recording
[0036] Multiple linear regression analysis was performed for
prediction of central aortic systolic blood pressure. This model
will include primarily the systolic blood pressure estimated from
brachial pulse volume recording, age, gender, body weight, height,
waist circumference, hip girdle length, and disease history.
Central aortic systolic blood pressure was used as dependent
variable. Unvaried correlation analyses with central aortic
systolic blood pressure were performed and variables above with p
value less than 0.15 were selected as independent variables in the
model. Model R2, partial R2, and .beta. coefficient, were
calculated for prediction of central aortic systolic blood
pressure.
[0037] Statistical analysis was performed using SPSS 13.0. For
assessment of parameters derived from tonometry and pulse volume
recording, a paired student t test was performed. Simple linear
regression was used to determine the relationship between measured
parameters. A value of p=0.05 was considered statistically
significant. The result was shown in FIG. 4, wherein the prediction
of central aortic systolic blood pressure is similar to the real
one before the nitroglycerine treatment, and so did the prediction
after 3 minutes of the nitroglycerine treatment.
Example 2
[0038] FIG. 5 showed the result of the application of the present
invention on 262 experimenters, who have taken the carotid arterial
pressure measurement simultaneously. The carotid arterial pressure,
which was obtained from the recording of pressure waveform by
non-invasive recorder via the adjustment of the brachium arterial
average pressure and the brachium arterial diastolic blood pressure
measured by electronic manometer, could represent the central
arterial pressure. The comparison of the 262 experimenters in basic
situation was shown in FIG. 5 A, wherein 85 were treated by
nitroglycerine and were tested again after 3 minutes (the result
was shown in FIG. 5 B). According to the result, the device and the
method of the present invention both measured the central arterial
systolic blood pressure accurately under the basic and
nitroglycerine-treated situation.
* * * * *