CA2689278C - A method of deriving central aortic systolic pressure and a method of analysing arterial waveform data to derive central aortic systolic pressure values - Google Patents
A method of deriving central aortic systolic pressure and a method of analysing arterial waveform data to derive central aortic systolic pressure values Download PDFInfo
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- 230000035488 systolic blood pressure Effects 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 59
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- 238000012935 Averaging Methods 0.000 claims abstract description 16
- 238000012545 processing Methods 0.000 claims description 7
- 238000009827 uniform distribution Methods 0.000 claims description 5
- 238000004458 analytical method Methods 0.000 claims 2
- 230000036772 blood pressure Effects 0.000 description 11
- 238000005259 measurement Methods 0.000 description 5
- 208000019622 heart disease Diseases 0.000 description 3
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- 239000002131 composite material Substances 0.000 description 1
- 230000003205 diastolic effect Effects 0.000 description 1
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- 230000005802 health problem Effects 0.000 description 1
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- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/021—Measuring pressure in heart or blood vessels
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/0205—Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
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- A—HUMAN NECESSITIES
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- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/021—Measuring pressure in heart or blood vessels
- A61B5/02108—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics
- A61B5/02116—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics of pulse wave amplitude
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/024—Detecting, measuring or recording pulse rate or heart rate
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Abstract
A method of deriving central aortic systolic pressure comprising the steps of: a) creating a set having a predetermined number of blood pressure measurements, the set representative of an arterial waveform; b) determining an integer interval value; c) averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from the f thblood pressure measurement in the set; d) storing the averaged value in a central aortic systolic pressure set; and e) setting the central aortic systolic pressure as the highest value in the central aortic pressure set, where steps c. and d. are repeated with the value of f being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set.
Description
2 "A METHOD OF DERIVING CENTRAL AORTIC SYSTOLIC PRESSURE AND
A METHOD OF ANALYSING ARTERIAL WAVEFORM DATA TO DERIVE
CENTRAL AORTIC SYSTOLIC PRESSURE VALUES"
FIELD OF THE INVENTION
The invention relates to a method of deriving the central aortic systolic pressure and a method of analysing arterial waveform data to derive central aortic systolic pressure values. In accordance with the first method of the invention, the invention is particularly suited to deriving the central aortic systolic pressure from an arterial waveform. However, in accordance with the second method of the invention, the invention is suited towards analysing an arterial waveform dataset to derive a corresponding central aortic systolic pressure dataset.
BACKGROUND TO THE INVENTION
The following discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known or part of the common general knowledge in any jurisdiction as at the priority date of the application.
Heart disease is a serious health problem in developed countries. One indicator of potential heart disease is variances in the blood pressure of the living body from a designated range of "normal" values.
A common method of determining the blood pressure of a living body is to take a brachial blood pressure reading (both systolic and diastolic) of the living body using a pressure cuff. These values are commonly then used as surrogate central aortic pressure values. While this assumption has historically been proven as beneficial in indicating potential heart disease, recent studies have shown that a "normal" brachial blood pressure value measured in this manner may mask abnormal central aortic systolic pressure values.
SUMMARY OF THE INVENTION
Throughout this document, unless otherwise indicated to the contrary, the terms "comprising", "consisting of", and the like, are to be construed as non-exhaustive, or in other words, as meaning "including, but not limited to".
In the context of the present description of the embodiments of the invention, the term "living body" is a reference to the body at the time of generation of the arterial waveform. The invention is not to be considered as limited to exclude the calculation of a central aortic pressure value from an arterial waveform of a since deceased patient.
In accordance with a first aspect of the invention there is a method of deriving central aortic systolic pressure comprising the steps of:
a) creating a set having a predetermined number of blood pressure measurements, the set representative of an arterial waveform;
b) determining an integer interval value;
c) averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an /I" blood pressure measurement in the set;
d) storing the averaged value in a central aortic systolic pressure set; and e) setting the central aortic systolic pressure as the highest value in the central aortic pressure set, where steps c. and d. are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set.
The set of blood pressure measurements should substantially equate to a uniform distribution of values from the arterial waveform. In particular, the method preferably includes the step of determining the duration of the arterial waveform. The duration of the wave form can then be used to determine the predetermined number according to the following formula:
Predetermined number = sr x t where sr = the sample rate, in Hz, of a measuring device used to record the blood pressure measurements in the set; and t = the duration of the arterial waveform The integer interval value may be division of the sample rate. Ideally, however, the integer interval value is the sample rate divided by 4.
Alternatively, the integer interval value may be a division of the predetermined number of blood pressure measurements in the set of blood pressure measurements. Ideally, using this technique, the integer interval value may fall within a range the boundaries of which are determined as follows:
'range = n/(t x v) (n/(t x 30)) where n is the predetermined number of blood pressure measurements in the set;
t is the duration of the waveform (in seconds); and v is a predetermined division value.
It is preferred, but not essential, that in calculating the above range, the value of v be set to 4.
In one alternative configuration, the integer interval value is equal to 60 divided by a predetermined division value. In another alternative configuration, the integer interval value is 15.
A METHOD OF ANALYSING ARTERIAL WAVEFORM DATA TO DERIVE
CENTRAL AORTIC SYSTOLIC PRESSURE VALUES"
FIELD OF THE INVENTION
The invention relates to a method of deriving the central aortic systolic pressure and a method of analysing arterial waveform data to derive central aortic systolic pressure values. In accordance with the first method of the invention, the invention is particularly suited to deriving the central aortic systolic pressure from an arterial waveform. However, in accordance with the second method of the invention, the invention is suited towards analysing an arterial waveform dataset to derive a corresponding central aortic systolic pressure dataset.
BACKGROUND TO THE INVENTION
The following discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known or part of the common general knowledge in any jurisdiction as at the priority date of the application.
Heart disease is a serious health problem in developed countries. One indicator of potential heart disease is variances in the blood pressure of the living body from a designated range of "normal" values.
A common method of determining the blood pressure of a living body is to take a brachial blood pressure reading (both systolic and diastolic) of the living body using a pressure cuff. These values are commonly then used as surrogate central aortic pressure values. While this assumption has historically been proven as beneficial in indicating potential heart disease, recent studies have shown that a "normal" brachial blood pressure value measured in this manner may mask abnormal central aortic systolic pressure values.
SUMMARY OF THE INVENTION
Throughout this document, unless otherwise indicated to the contrary, the terms "comprising", "consisting of", and the like, are to be construed as non-exhaustive, or in other words, as meaning "including, but not limited to".
In the context of the present description of the embodiments of the invention, the term "living body" is a reference to the body at the time of generation of the arterial waveform. The invention is not to be considered as limited to exclude the calculation of a central aortic pressure value from an arterial waveform of a since deceased patient.
In accordance with a first aspect of the invention there is a method of deriving central aortic systolic pressure comprising the steps of:
a) creating a set having a predetermined number of blood pressure measurements, the set representative of an arterial waveform;
b) determining an integer interval value;
c) averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an /I" blood pressure measurement in the set;
d) storing the averaged value in a central aortic systolic pressure set; and e) setting the central aortic systolic pressure as the highest value in the central aortic pressure set, where steps c. and d. are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set.
The set of blood pressure measurements should substantially equate to a uniform distribution of values from the arterial waveform. In particular, the method preferably includes the step of determining the duration of the arterial waveform. The duration of the wave form can then be used to determine the predetermined number according to the following formula:
Predetermined number = sr x t where sr = the sample rate, in Hz, of a measuring device used to record the blood pressure measurements in the set; and t = the duration of the arterial waveform The integer interval value may be division of the sample rate. Ideally, however, the integer interval value is the sample rate divided by 4.
Alternatively, the integer interval value may be a division of the predetermined number of blood pressure measurements in the set of blood pressure measurements. Ideally, using this technique, the integer interval value may fall within a range the boundaries of which are determined as follows:
'range = n/(t x v) (n/(t x 30)) where n is the predetermined number of blood pressure measurements in the set;
t is the duration of the waveform (in seconds); and v is a predetermined division value.
It is preferred, but not essential, that in calculating the above range, the value of v be set to 4.
In one alternative configuration, the integer interval value is equal to 60 divided by a predetermined division value. In another alternative configuration, the integer interval value is 15.
- 3 -, The predetermined number of blood pressure measurements in the set is equal to or greater than 15. However, it is preferred that the predetermined number of blood pressure measurements in the set is at least 30.
In its most preferred arrangement the predetermined number of blood pressure measurements in the set is at least 30 and the interval is 15.
In accordance with a second aspect of the invention there is a method of analysing arterial waveform data to derive central aortic systolic pressure values comprising the steps of:
a. receiving an arterial waveform dataset b. dividing each arterial waveform in the arterial waveform dataset into a representative set of blood pressure measurements having a predetermined number;
c. determining an integer interval value for the set being processed;
d. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an fth blood pressure measurement in the set;
e. storing the averaged value in a central aortic systolic pressure set; and f. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where steps b. through f. are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, steps d. and e. are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
In its most preferred arrangement the predetermined number of blood pressure measurements in the set is at least 30 and the interval is 15.
In accordance with a second aspect of the invention there is a method of analysing arterial waveform data to derive central aortic systolic pressure values comprising the steps of:
a. receiving an arterial waveform dataset b. dividing each arterial waveform in the arterial waveform dataset into a representative set of blood pressure measurements having a predetermined number;
c. determining an integer interval value for the set being processed;
d. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an fth blood pressure measurement in the set;
e. storing the averaged value in a central aortic systolic pressure set; and f. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where steps b. through f. are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, steps d. and e. are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
- 4 -In accordance with a third aspect of the invention there is a method of analysing arterial waveform data to derive central aortic systolic pressure values comprising the steps of:
a. receiving an arterial waveform dataset, where each arterial waveform in the dataset comprises a representative set of blood pressure measurements having a predetermined number;
b. determining an integer interval value for the set being processed;
c. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an h blood pressure measurement in the set;
d. storing the averaged value in a central aortic systolic pressure set; and e. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where steps b. through e. are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, steps c. and d. are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
The predetermined number of blood pressure measurements for at least one arterial waveform in the dataset may differ from the predetermined number of blood pressure measurements for the other arterial waveforms in the dataset.
In respect of both the second and third aspects of the invention, the set of blood pressure measurements should substantially equate to a uniform distribution of values from the arterial waveform.
a. receiving an arterial waveform dataset, where each arterial waveform in the dataset comprises a representative set of blood pressure measurements having a predetermined number;
b. determining an integer interval value for the set being processed;
c. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an h blood pressure measurement in the set;
d. storing the averaged value in a central aortic systolic pressure set; and e. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where steps b. through e. are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, steps c. and d. are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
The predetermined number of blood pressure measurements for at least one arterial waveform in the dataset may differ from the predetermined number of blood pressure measurements for the other arterial waveforms in the dataset.
In respect of both the second and third aspects of the invention, the set of blood pressure measurements should substantially equate to a uniform distribution of values from the arterial waveform.
- 5 -Ideally, the method further includes the step of determining the duration of the arterial waveform. The duration of the wave form can then be used to determine the predetermined number according to the following formula:
Predetermined number = sr x t where sr = the sample rate, in Hz, of a measuring device used to record the blood pressure measurements in the set; and t = the duration of the arterial waveform The integer interval value may be a division of the sample rate (sr).
Preferably, the integer interval value is the sample rate divided by 4.
Alternatively, the integer interval value may be a division of the predetermined number of blood pressure measurements in the set of blood pressure measurements. Ideally, using this technique, the integer interval value is within a range the boundaries of which are determined as follows:
'range = n/(t x v) (nit x 30)) where n is the predetermined number of blood pressure measurements in the set;
t = the duration of the waveform (in seconds); and v is a predetermined division value.
In this formula, it is further preferred that the value of v be set to 4.
In one alternative configuration, the integer interval value is equal to 60 divided by a predetermined division value. In another alternative configuration, the integer interval value is 15.
Predetermined number = sr x t where sr = the sample rate, in Hz, of a measuring device used to record the blood pressure measurements in the set; and t = the duration of the arterial waveform The integer interval value may be a division of the sample rate (sr).
Preferably, the integer interval value is the sample rate divided by 4.
Alternatively, the integer interval value may be a division of the predetermined number of blood pressure measurements in the set of blood pressure measurements. Ideally, using this technique, the integer interval value is within a range the boundaries of which are determined as follows:
'range = n/(t x v) (nit x 30)) where n is the predetermined number of blood pressure measurements in the set;
t = the duration of the waveform (in seconds); and v is a predetermined division value.
In this formula, it is further preferred that the value of v be set to 4.
In one alternative configuration, the integer interval value is equal to 60 divided by a predetermined division value. In another alternative configuration, the integer interval value is 15.
- 6 -The predetermined number of blood pressure measurements in the set should be equal to or greater than 15. A set of 30 blood pressure measurements is preferred.
In accordance with a fourth aspect of the invention there is a system for deriving central aortic systolic pressure comprising:
an arterial waveform measuring device; and a processing unit, where, the arterial waveform measuring device takes a blood pressure measurement at predetermined intervals until at least one arterial waveform is represented by the set of blood pressure measurements taken, the set of blood pressure measurements representative of one arterial waveform then being communicated to the processing unit which:
a) determines an integer interval value;
b) averages a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an /I" blood pressure measurement in the set;
c) stores the averaged value in a central aortic systolic pressure set; and d) sets the central aortic systolic pressure as the highest value in the central aortic pressure set, wherein steps b. and c. are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the number of blood pressure measurements in the set.
In accordance with further aspects of the invention there are computer readable storage medium having instructions recorded thereon to perform the methods described in the first, second and third aspects of the invention.
In accordance with a fourth aspect of the invention there is a system for deriving central aortic systolic pressure comprising:
an arterial waveform measuring device; and a processing unit, where, the arterial waveform measuring device takes a blood pressure measurement at predetermined intervals until at least one arterial waveform is represented by the set of blood pressure measurements taken, the set of blood pressure measurements representative of one arterial waveform then being communicated to the processing unit which:
a) determines an integer interval value;
b) averages a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an /I" blood pressure measurement in the set;
c) stores the averaged value in a central aortic systolic pressure set; and d) sets the central aortic systolic pressure as the highest value in the central aortic pressure set, wherein steps b. and c. are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the number of blood pressure measurements in the set.
In accordance with further aspects of the invention there are computer readable storage medium having instructions recorded thereon to perform the methods described in the first, second and third aspects of the invention.
- 7 -BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a flow chart of a method of determining the central aortic pressure of a living body in accordance with a first embodiment of the present invention.
Figure 2 is a flow chart of a method of analysing an arterial waveform dataset to produce a corresponding central aortic pressure dataset in accordance with a second embodiment of the present invention.
Figure 3 is an illustrative arterial waveform that can be processed by any embodiment of the current invention to obtain a central aortic pressure value.
PREFERRED EMBODIMENTS OF THE INVENTION
Particular embodiments of the present invention will now be described with reference to the accompany drawings. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention. Additionally, unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one or ordinary skill in the art to which this invention belongs.
In accordance with a first embodiment of the invention there is a method of determining central aortic pressure 10. The method 10 is illustrated in flow chart form in Figure 1.
As shown in Figure 1, the method 10 commences by the creation of a set of blood pressure measurements from a living body representative of an arterial waveform (step 12). The set of blood pressure measurements has a predetermined number of measurements (n). At step 14, the predetermined
The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 is a flow chart of a method of determining the central aortic pressure of a living body in accordance with a first embodiment of the present invention.
Figure 2 is a flow chart of a method of analysing an arterial waveform dataset to produce a corresponding central aortic pressure dataset in accordance with a second embodiment of the present invention.
Figure 3 is an illustrative arterial waveform that can be processed by any embodiment of the current invention to obtain a central aortic pressure value.
PREFERRED EMBODIMENTS OF THE INVENTION
Particular embodiments of the present invention will now be described with reference to the accompany drawings. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention. Additionally, unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one or ordinary skill in the art to which this invention belongs.
In accordance with a first embodiment of the invention there is a method of determining central aortic pressure 10. The method 10 is illustrated in flow chart form in Figure 1.
As shown in Figure 1, the method 10 commences by the creation of a set of blood pressure measurements from a living body representative of an arterial waveform (step 12). The set of blood pressure measurements has a predetermined number of measurements (n). At step 14, the predetermined
- 8 -number n is divided by a preset value (v) to determine an integer interval value (0. In this manner, the integer interval value (0 may be subjected to an absolute or rounding mathematical function.
The following steps are then repeated, commencing with a first blood pressure measurement bp[(f)]:
The blood pressure measurements {bp[f], bp[f+/], bp[f+2], bp[f+3], bp[f+/-1]} are summed (step 16) to form a value s;
The summed value s be divided by the interval value i to form an average blood pressure value (a) (step 18).
The average blood pressure value a is stored in a central aortic pressure set of values (step 20).
The above steps (steps 16 to 20) are repeated until f+ I¨ 1 is equal to n.
Step 22 sees the central aortic pressure set of values analysed to determine the highest value in the set (h). The highest value h is then used as a value substantially representative of the central aortic systolic pressure of the living body.
In accordance with a second embodiment of the present invention there is a method of analysing an arterial waveform dataset to produce a corresponding central aortic pressure dataset 100. A common precursor to this embodiment is that a medical professional obtains an arterial waveform representation of the blood pressure of a living body according to any technique as would be known to the person skilled in the art. This arterial waveform representation is then provided to a central processing station for determination of the corresponding central aortic pressure. Following receipt of the arterial waveform representation the central processing station operates as follows:
For each arterial waveform in the waveform dataset, a corresponding central aortic pressure value a is determined and stored in the central aortic pressure dataset according to the following process.
The following steps are then repeated, commencing with a first blood pressure measurement bp[(f)]:
The blood pressure measurements {bp[f], bp[f+/], bp[f+2], bp[f+3], bp[f+/-1]} are summed (step 16) to form a value s;
The summed value s be divided by the interval value i to form an average blood pressure value (a) (step 18).
The average blood pressure value a is stored in a central aortic pressure set of values (step 20).
The above steps (steps 16 to 20) are repeated until f+ I¨ 1 is equal to n.
Step 22 sees the central aortic pressure set of values analysed to determine the highest value in the set (h). The highest value h is then used as a value substantially representative of the central aortic systolic pressure of the living body.
In accordance with a second embodiment of the present invention there is a method of analysing an arterial waveform dataset to produce a corresponding central aortic pressure dataset 100. A common precursor to this embodiment is that a medical professional obtains an arterial waveform representation of the blood pressure of a living body according to any technique as would be known to the person skilled in the art. This arterial waveform representation is then provided to a central processing station for determination of the corresponding central aortic pressure. Following receipt of the arterial waveform representation the central processing station operates as follows:
For each arterial waveform in the waveform dataset, a corresponding central aortic pressure value a is determined and stored in the central aortic pressure dataset according to the following process.
- 9 -The arterial waveform 102 being processed is divided into a set of representative blood pressure measurements (step 110). The set of blood pressure measurements has a predetermined number of measurements (n). At step 112, the predetermined number n is divided by a preset value (v) to determine an integer interval value (i).
The following steps are then repeated, commencing with a first blood pressure measurement bp[(f)]:
The blood pressure measurements {bp[f], bp[f+ bp[f+2], bp[f+3], bp[f-Fi-1]) are summed (step 114) to form a value s;
The summed value s be divided by the interval value i to form an average blood pressure value (a) (step 116).
The average blood pressure value a is stored in a central aortic pressure set of values (step 118).
The above steps (steps 114 to 118) are repeated until f + i ¨ 1 is equal to n.
Step 120 sees the central aortic pressure set of values analysed to determine the highest value in the set (h). The highest value h is then stored in the central aortic pressure dataset as the central aortic systolic pressure value corresponding with the arterial waveform processed.
The above steps are then repeated until such time as a corresponding central aortic pressure value has been calculated for each arterial waveform in the waveform dataset.
In accordance with a third embodiment of the invention, where like numerals reference like steps, there is a method of analysing an arterial waveform dataset to produce a corresponding central aortic pressure dataset (not shown). This embodiment is based on experiments conducted by the applicant where it has been found that the n value can be any value in excess of 15.
In this embodiment, while it is preferred that the v value be 4 to determine an appropriate interval, a substantially accurate aortic pressure value has been able
The following steps are then repeated, commencing with a first blood pressure measurement bp[(f)]:
The blood pressure measurements {bp[f], bp[f+ bp[f+2], bp[f+3], bp[f-Fi-1]) are summed (step 114) to form a value s;
The summed value s be divided by the interval value i to form an average blood pressure value (a) (step 116).
The average blood pressure value a is stored in a central aortic pressure set of values (step 118).
The above steps (steps 114 to 118) are repeated until f + i ¨ 1 is equal to n.
Step 120 sees the central aortic pressure set of values analysed to determine the highest value in the set (h). The highest value h is then stored in the central aortic pressure dataset as the central aortic systolic pressure value corresponding with the arterial waveform processed.
The above steps are then repeated until such time as a corresponding central aortic pressure value has been calculated for each arterial waveform in the waveform dataset.
In accordance with a third embodiment of the invention, where like numerals reference like steps, there is a method of analysing an arterial waveform dataset to produce a corresponding central aortic pressure dataset (not shown). This embodiment is based on experiments conducted by the applicant where it has been found that the n value can be any value in excess of 15.
In this embodiment, while it is preferred that the v value be 4 to determine an appropriate interval, a substantially accurate aortic pressure value has been able
- 10-to be obtained where the interval value is in a range, the limits of which are determined as follows:
'range = n/(t x v) (n/(t x 30)) where in this embodiment, the variable t is representative of the duration of a single waveform (in seconds).
This embodiment will now be described in more detail in the context of the following example:
In accordance with step 12, a set of blood pressure measurements from a living body representative of an arterial waveform are created. The measurements are as follows (in order, from left to right, top to bottom):
62.0 63.6 73.1 91.1 112.3 132.1 149.6 165.4 176.0 180.7 182.0 181.9 181.3 180.2 178.8 176.8 174.4 171.5 167.9 163.1 156.4 147.8 137.1 125.1 114.0 106.2 102.3 101.1 100.7 99.8 98.2 95.9 93.2 90.6 88.1 85.8 83.9 82.2 80.4 78.7 77.2 76.2 75.5 74.7 73.7 72.7 72.0 71.5 71.1 70.5 69.9 69.1 68.4 67.5 66.9 66.1 65.5 65.1 64.9 64.8 64.4 63.8 63.3 62.9 62.7 62.8 63.1 63.3 63.5 63.6 63.6 63.5 63.4 63.0 62.5 62.0 The time duration taken to complete this waveform is 1.27 seconds.
This sets the n value at 76. With a v value of 4, the interval value range (irange) is determined as follows:
'range = n/(t x v) (n/(t x 30)), therefore 'range = 76/(1.27 x 4) (76/(1.27 x 30)), therefore 'range = 14.96 (1.99)
'range = n/(t x v) (n/(t x 30)) where in this embodiment, the variable t is representative of the duration of a single waveform (in seconds).
This embodiment will now be described in more detail in the context of the following example:
In accordance with step 12, a set of blood pressure measurements from a living body representative of an arterial waveform are created. The measurements are as follows (in order, from left to right, top to bottom):
62.0 63.6 73.1 91.1 112.3 132.1 149.6 165.4 176.0 180.7 182.0 181.9 181.3 180.2 178.8 176.8 174.4 171.5 167.9 163.1 156.4 147.8 137.1 125.1 114.0 106.2 102.3 101.1 100.7 99.8 98.2 95.9 93.2 90.6 88.1 85.8 83.9 82.2 80.4 78.7 77.2 76.2 75.5 74.7 73.7 72.7 72.0 71.5 71.1 70.5 69.9 69.1 68.4 67.5 66.9 66.1 65.5 65.1 64.9 64.8 64.4 63.8 63.3 62.9 62.7 62.8 63.1 63.3 63.5 63.6 63.6 63.5 63.4 63.0 62.5 62.0 The time duration taken to complete this waveform is 1.27 seconds.
This sets the n value at 76. With a v value of 4, the interval value range (irange) is determined as follows:
'range = n/(t x v) (n/(t x 30)), therefore 'range = 76/(1.27 x 4) (76/(1.27 x 30)), therefore 'range = 14.96 (1.99)
- 11 -As it is not possible for intervals to be anything other than integer values, the 'range value is restricted to the range of 13 to 17. For the purposes of this example, an /value of 15 shall be used.
Following the requirements of steps 16 through 20, a central aortic pressure set of values is created having the following values:
{140.7 148.3 155.7 162.3 167.4 170.8 172.4 172.3 170.4 167.0 162.5 157.5 152.2 146.8 141.5 136.3 131.0 125.8 120.6 115.4 110.4 105.7 101.5 97.8 94.8 92.5 90.5 88.8 87.1 85.4 83.6 81.9 80.3 78.9 77.6 76.4 75.3 74.4 73.4 72.6 71.8 71.1 70.3 69.6 69.0 68.4 67.8 67.3 66.7 66.2 65.7 65.2 64.8 64.5 64.2 64.0 63.8 63.7 63.6 64.5 63.3 63.1}
As can be seen the central aortic pressure set of values has 62 elements to it, being the value equal to n - i + 1. From this set, it is apparent that the highest value in the set (h) is in fact the seventh data element (172.4). Accordingly the central aortic systolic pressure of the living body is determined as 172.4.
In a fourth, and most preferred embodiment of the invention, there is a method of determining central aortic pressure as described in the first embodiment of the invention. However, in this embodiment, the predetermined number n is determined according to the following formula:
n = sr x t
Following the requirements of steps 16 through 20, a central aortic pressure set of values is created having the following values:
{140.7 148.3 155.7 162.3 167.4 170.8 172.4 172.3 170.4 167.0 162.5 157.5 152.2 146.8 141.5 136.3 131.0 125.8 120.6 115.4 110.4 105.7 101.5 97.8 94.8 92.5 90.5 88.8 87.1 85.4 83.6 81.9 80.3 78.9 77.6 76.4 75.3 74.4 73.4 72.6 71.8 71.1 70.3 69.6 69.0 68.4 67.8 67.3 66.7 66.2 65.7 65.2 64.8 64.5 64.2 64.0 63.8 63.7 63.6 64.5 63.3 63.1}
As can be seen the central aortic pressure set of values has 62 elements to it, being the value equal to n - i + 1. From this set, it is apparent that the highest value in the set (h) is in fact the seventh data element (172.4). Accordingly the central aortic systolic pressure of the living body is determined as 172.4.
In a fourth, and most preferred embodiment of the invention, there is a method of determining central aortic pressure as described in the first embodiment of the invention. However, in this embodiment, the predetermined number n is determined according to the following formula:
n = sr x t
- 12 -where sr = the sample rate (in hertz) of a measuring device used to record the blood pressure measurements in the set bp; and t = the time taken (in seconds) to complete one arterial waveform.
In this embodiment, the blood pressure measurements in the set bp are the measurement values taken by the measuring device at each repetition of the sample rate. Furthermore, in this embodiment of the invention, the interval value is in a range, the limits of which are determined as follows:
'range = sr/v (sr/30) In this case, sr again represents the sample rate (in hertz) of a measuring device used to record the blood pressure measurements in the set bp. Additionally, the v value is preferably 4. This formula is only applicable though when the sr value is in excess of 30.
Using the same set of blood pressure measurements as set out above, but this time in a situation where the set is the culmination of blood pressure values taken by a sampling device having a sample rate (sr) of 60 measurements per second, the 'range value is calculated as follows:
'range = sr/v (sr/30) 'range = 60/4 (60/30) 'range = 15 2 This results in an 'range value of between 13 and 17. The rest of the method can then proceed as set out in the first embodiment above.
It should be appreciated by the person skilled in the art that the above invention is not limited to the embodiments described. In particular, the following modifications and improvements may be made without departing from the scope of the present invention:
In this embodiment, the blood pressure measurements in the set bp are the measurement values taken by the measuring device at each repetition of the sample rate. Furthermore, in this embodiment of the invention, the interval value is in a range, the limits of which are determined as follows:
'range = sr/v (sr/30) In this case, sr again represents the sample rate (in hertz) of a measuring device used to record the blood pressure measurements in the set bp. Additionally, the v value is preferably 4. This formula is only applicable though when the sr value is in excess of 30.
Using the same set of blood pressure measurements as set out above, but this time in a situation where the set is the culmination of blood pressure values taken by a sampling device having a sample rate (sr) of 60 measurements per second, the 'range value is calculated as follows:
'range = sr/v (sr/30) 'range = 60/4 (60/30) 'range = 15 2 This results in an 'range value of between 13 and 17. The rest of the method can then proceed as set out in the first embodiment above.
It should be appreciated by the person skilled in the art that the above invention is not limited to the embodiments described. In particular, the following modifications and improvements may be made without departing from the scope of the present invention:
- 13-= The set of blood pressure measurements may be obtained from a device that is also adapted to perform the method of the present invention. Alternatively, the set of blood pressure measurements may be obtained from a separate device and communicated to a further apparatus adapted to perform the method of the present invention.
= The second embodiment of the invention may be modified such that the waveform dataset does not contain waveforms - in its place the waveform dataset data may contain sets of data representative of such waveforms. In this manner, the processing of step 110 may be omitted.
= The waveform dataset may be supplied to the entity performing the method along with the duration of each waveform in the dataset.
Alternatively, the entity performing the method may determine the duration of each waveform independently through alternate means (such as by receiving graphs having a fixed time value for predetermined lengths of the x axis and approximating the duration of the waveform based on this time/distance relationship or by deriving the duration from other composite values, such as the sample rate used to generate the set of blood pressure measurements)..
= To be the most representative of an arterial waveform, the blood pressure values that form the set bp should be of uniform distribution along the arterial waveform.
It should be further appreciated by the person skilled in the art that the features described above, where not mutually exclusive, can be combined to form yet further embodiments of the invention.
= The second embodiment of the invention may be modified such that the waveform dataset does not contain waveforms - in its place the waveform dataset data may contain sets of data representative of such waveforms. In this manner, the processing of step 110 may be omitted.
= The waveform dataset may be supplied to the entity performing the method along with the duration of each waveform in the dataset.
Alternatively, the entity performing the method may determine the duration of each waveform independently through alternate means (such as by receiving graphs having a fixed time value for predetermined lengths of the x axis and approximating the duration of the waveform based on this time/distance relationship or by deriving the duration from other composite values, such as the sample rate used to generate the set of blood pressure measurements)..
= To be the most representative of an arterial waveform, the blood pressure values that form the set bp should be of uniform distribution along the arterial waveform.
It should be further appreciated by the person skilled in the art that the features described above, where not mutually exclusive, can be combined to form yet further embodiments of the invention.
-14-
Claims (30)
1. A method of deriving central aortic systolic pressure comprising the steps of:
a. creating a set having a predetermined number of blood pressure measurements, the set representative of an arterial waveform;
b. determining an integer interval value;
c. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
d. storing the averaged value in a central aortic systolic pressure set; and e. setting the central aortic systolic pressure as the highest value in the central aortic pressure set, where steps c. and d. are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set.
a. creating a set having a predetermined number of blood pressure measurements, the set representative of an arterial waveform;
b. determining an integer interval value;
c. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
d. storing the averaged value in a central aortic systolic pressure set; and e. setting the central aortic systolic pressure as the highest value in the central aortic pressure set, where steps c. and d. are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set.
2. A method of deriving central aortic systolic pressure according to claim 1 where the set of blood pressure measurements substantially equates to a uniform distribution of values from the arterial waveform.
3. A method of deriving central aortic systolic pressure according to claim 2, further including the step of determining the duration of the arterial waveform and where the predetermined number of blood pressure measurement is determined according to the following formula:
Predetermined number = sr x t where sr = the sample rate, in Hz, of a measuring device used to record the blood pressure measurements in the set; and t = the duration of the arterial waveform.
Predetermined number = sr x t where sr = the sample rate, in Hz, of a measuring device used to record the blood pressure measurements in the set; and t = the duration of the arterial waveform.
4. A method of deriving central aortic systolic pressure according to claim 3, where the integer interval value is a division of the sample rate.
5. A method of deriving central aortic systolic pressure according to claim 4 where the integer interval value is the sample rate divided by 4.
6. A method of deriving central aortic systolic pressure according to claim 1 or claim 2, where the interger interval value is a division of the predetermined number.
7. A method of deriving central aortic systolic pressure according to claim 6, where the integer interval value is within a range the boundaries of which are determined as follows:
i range = n/(t x v) ~ (n/(t x 30)) where n is the predetermined number of blood pressure measurements in the set;
t is the duration of the waveform (in seconds); and v is a predetermined division value.
i range = n/(t x v) ~ (n/(t x 30)) where n is the predetermined number of blood pressure measurements in the set;
t is the duration of the waveform (in seconds); and v is a predetermined division value.
8. A method of deriving central aortic systolic pressure according to claim 7, where v = 4.
9. A method of deriving central aortic systolic pressure according to claim 1 or claim 2, where the integer interval value is equal to 60 divided by a predetermined division value.
10.A method of deriving central aortic systolic pressure according to claim 9, where the integer interval value is 15.
11.A method of deriving central aortic systolic pressure according to any one of claims 1 to 10, where the predetermined number of blood pressure measurements in the set is equal to or greater than 15.
12.A method of deriving central aortic systolic pressure according to claim 11, where the predetermined number of blood pressure measurements in the set is at least 30.
13.A method of analysing arterial waveform data to derive central aortic systolic pressure values comprising the steps of:
a. receiving an arterial waveform dataset;
b. dividing each arterial waveform in the arterial waveform dataset into a representative set of blood pressure measurements having a predetermined number;
c. determining an integer interval value for the set being processed;
d. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
e. storing the averaged value in a central aortic systolic pressure set; and f. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where steps b. through f. are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, steps d. and e. are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
a. receiving an arterial waveform dataset;
b. dividing each arterial waveform in the arterial waveform dataset into a representative set of blood pressure measurements having a predetermined number;
c. determining an integer interval value for the set being processed;
d. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
e. storing the averaged value in a central aortic systolic pressure set; and f. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where steps b. through f. are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, steps d. and e. are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
14.A method of analysing arterial waveform data to derive central aortic systolic pressure values comprising the steps of:
a. receiving an arterial waveform dataset, where each arterial waveform in the dataset comprises a representative set of blood pressure measurements having a predetermined number;
b. determining an integer interval value for the set being processed;
c. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
d. storing the averaged value in a central aortic systolic pressure set; and e. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where steps b. through e. are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, steps c. and d. are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
a. receiving an arterial waveform dataset, where each arterial waveform in the dataset comprises a representative set of blood pressure measurements having a predetermined number;
b. determining an integer interval value for the set being processed;
c. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
d. storing the averaged value in a central aortic systolic pressure set; and e. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where steps b. through e. are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, steps c. and d. are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
15.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to claim 14, where the predetermined number of blood pressure measurements for at least one arterial waveform in the dataset differs from the predetermined number of blood pressure measurements for the other arterial waveforms in the dataset.
16.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to any one of claims 13 to 15, where the set of blood pressure measurements substantially equates to a uniform distribution of values from the arterial waveform.
17.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to claim 16, further including the step of determining the duration of the arterial waveform and where the predetermined number of blood pressure measurement is determined according to the following formula:
Predetermined number = sr x t where sr = the sample rate, in Hz, f a measuring device used to record the blood pressure measurements in the set; and t = the duration of the arterial waveform.
Predetermined number = sr x t where sr = the sample rate, in Hz, f a measuring device used to record the blood pressure measurements in the set; and t = the duration of the arterial waveform.
18.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to any one of claims 13 to 17, where the integer interval value is a division of the sample rate.
19.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to claim 18, where the integer interval value is the sample rate divided by 4.
20.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to any one of claims 13 to 17, where the integer interval value is a division of the predetermined number.
21.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to claim 20, where the integer interval value is within a range the boundaries of which are determined as follows:
i range = n/(t x v) ~ (n/(t x 30)) where n is the predetermined number of blood pressure measurements in the set;
t is the duration of the waveform (in seconds); and v is a predetermined division value.
i range = n/(t x v) ~ (n/(t x 30)) where n is the predetermined number of blood pressure measurements in the set;
t is the duration of the waveform (in seconds); and v is a predetermined division value.
22.A method of deriving central aortic systolic pressure according to claim 21, where v = 4.
23.A method of deriving central aortic systolic pressure according to claim 13 or claim 14, where the integer interval value is equal to 60 divided by a predetermined division value.
24.A method of deriving central aortic systolic pressure according to claim 23, where the integer interval value is 15.
25.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to any one of claims 13 to 24, where the predetermined number of blood pressure measurements in the set is equal to or greater than 15.
26.A method of analysing arterial waveform data to derive central aortic systolic pressure values according to claim 25, where the predetermined number of blood pressure measurements in the set is at least 30.
27.A system for deriving central aortic systolic pressure comprising:
an arterial waveform measuring device; and a processing unit, where, the arterial waveform measuring device takes a blood pressure measurement at predetermined intervals until at least one arterial waveform is represented by the set of blood pressure measurements taken, the set of blood pressure measurements representative of one arterial waveform then being communicated to the processing unit which:
a. determines an integer interval value;
b. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
c. stores the averaged value in a central aortic systolic pressure set; and d. sets the central aortic systolic pressure as the highest value in the central aortic pressure set, wherein steps b. and c. are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the number of blood pressure measurements in the set.
an arterial waveform measuring device; and a processing unit, where, the arterial waveform measuring device takes a blood pressure measurement at predetermined intervals until at least one arterial waveform is represented by the set of blood pressure measurements taken, the set of blood pressure measurements representative of one arterial waveform then being communicated to the processing unit which:
a. determines an integer interval value;
b. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
c. stores the averaged value in a central aortic systolic pressure set; and d. sets the central aortic systolic pressure as the highest value in the central aortic pressure set, wherein steps b. and c. are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the number of blood pressure measurements in the set.
28.A computer readable storage medium having instructions recorded thereon for execution by a computer device in order to derive central aortic systolic pressure, by performing the following steps:
creating a set having a predetermined number of blood pressure measurements, the set representative of an arterial waveform;
determining an integer interval value;
averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
storing the averaged value in a central aortic systolic pressure set; and setting the central aortic systolic pressure as the highest value in the central aortic pressure set, where the averaging step and storing step are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set.
creating a set having a predetermined number of blood pressure measurements, the set representative of an arterial waveform;
determining an integer interval value;
averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
storing the averaged value in a central aortic systolic pressure set; and setting the central aortic systolic pressure as the highest value in the central aortic pressure set, where the averaging step and storing step are repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set.
29.A computer readable storage medium having instructions recorded thereon for execution by a computer device in order to analyse arterial waveform data to derive central aortic systolic pressure values by performing the following steps:
receiving an arterial waveform dataset;
dividing each arterial waveform in the arterial waveform dataset into a representative set of blood pressure measurements having a predetermined number;
determining an integer interval value for the set being processed;
averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
storing the averaged value in a central aortic systolic pressure set; and storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where the steps of dividing, determining, averaging, storing the averaged value, and storing the highest value are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, the steps of averaging and storing the averaged value are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
receiving an arterial waveform dataset;
dividing each arterial waveform in the arterial waveform dataset into a representative set of blood pressure measurements having a predetermined number;
determining an integer interval value for the set being processed;
averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
storing the averaged value in a central aortic systolic pressure set; and storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where the steps of dividing, determining, averaging, storing the averaged value, and storing the highest value are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, the steps of averaging and storing the averaged value are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
30.A computer readable storage medium having instructions recorded thereon for execution by a computer device in order to analyse arterial waveform data to derive central aortic systolic pressure values, by performing the following steps:
a. receiving an arterial waveform dataset, where each arterial waveform in the dataset comprises a representative set of blood pressure measurements having a predetermined number;
b. determining an integer interval value for the set being processed;
c. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
d. storing the averaged value in a central aortic systolic pressure set; and e. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where the steps of determining, averaging, storing the averaged value and storing the highest value are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, the steps of averaging and storing the averaged value are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
a. receiving an arterial waveform dataset, where each arterial waveform in the dataset comprises a representative set of blood pressure measurements having a predetermined number;
b. determining an integer interval value for the set being processed;
c. averaging a series of consecutive blood pressure measurement readings in the set equal to the integer interval value commencing from an f th blood pressure measurement in the set;
d. storing the averaged value in a central aortic systolic pressure set; and e. storing the highest value in the central aortic pressure set in a central aortic systolic pressure value set at a position corresponding to the position the arterial waveform being processed occupies in the arterial waveform dataset, where the steps of determining, averaging, storing the averaged value and storing the highest value are repeated for each arterial waveform in the arterial waveform dataset and, for each such repetition, the steps of averaging and storing the averaged value are further repeated with the value of f commencing at 1 and being incremented by 1 each time until the value of f plus the integer interval value equals the predetermined number of blood pressure measurements in the set being processed.
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| PCT/SG2007/000161 WO2008150242A1 (en) | 2007-06-07 | 2007-06-07 | A method of deriving central aortic systolic pressure and a method of analysing arterial waveform data to derive central aortic systolic pressure values |
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| CA2689278C true CA2689278C (en) | 2015-11-17 |
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| JP3400417B2 (en) * | 2000-08-11 | 2003-04-28 | 日本コーリン株式会社 | Central artery pressure waveform estimation device |
| SG94349A1 (en) * | 2000-10-09 | 2003-02-18 | Healthstats Int Pte Ltd | Method and device for monitoring blood pressure |
| US6667384B2 (en) * | 2001-12-27 | 2003-12-23 | Hercules Incorporated | Methyl acrylate-diamine based polyamide resins and processes for producing the same |
| JP2004016745A (en) * | 2002-06-20 | 2004-01-22 | Nippon Colin Co Ltd | Blood pressure determining apparatus |
| EP1706030B1 (en) * | 2003-12-17 | 2013-07-03 | Atcor Medical Pty Ltd | Method and apparatus for determination of central aortic pressure |
| GB0500430D0 (en) * | 2005-01-10 | 2005-02-16 | Micro Medical Ltd | A method of obtaining an estimation of a person's aortic blood pressure |
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- 2007-06-07 BR BRPI0721728A patent/BRPI0721728A2/en not_active IP Right Cessation
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2008
- 2008-04-24 TW TW097115022A patent/TWI441618B/en not_active IP Right Cessation
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2009
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- 2009-11-25 IL IL202333A patent/IL202333A/en active IP Right Grant
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| AU2007354717A1 (en) | 2008-12-11 |
| IL202333A (en) | 2012-06-28 |
| TW200901935A (en) | 2009-01-16 |
| JP2010528757A (en) | 2010-08-26 |
| KR101476730B1 (en) | 2014-12-29 |
| IL202333A0 (en) | 2010-06-30 |
| GB2454624A (en) | 2009-05-20 |
| EP2162063A4 (en) | 2015-07-22 |
| CA2689278A1 (en) | 2008-12-11 |
| GB0723145D0 (en) | 2008-01-02 |
| EP2162063A1 (en) | 2010-03-17 |
| WO2008150242A1 (en) | 2008-12-11 |
| BRPI0721728A2 (en) | 2018-10-23 |
| MX2009013200A (en) | 2010-02-24 |
| GB2454624B (en) | 2012-09-12 |
| AU2007354717B2 (en) | 2012-08-16 |
| ZA200908221B (en) | 2011-02-23 |
| KR20100033381A (en) | 2010-03-29 |
| TWI441618B (en) | 2014-06-21 |
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