EP0152848A2
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EP
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Method for determining the pressure of a pulsatile fluid flowing through a flexible tube and apparatus for determinig arterial blood pressure in a subject
Assignee: Cortronic Corp
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Filing: 1985-02-04
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Granted: —
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Expires: 2005-02-04
Abstract
Abstract Apparatus and related methods for continuous long- term non-invasive measurement of the pressure of a pulsatile fluid flowing through a flexible tube, particularly human arterial blood flow, is disclosed. Specifically, the apparatus provides a continuous calibrated pressure measurement by first undertaking a «calibration» phase comprised of determining the pressure at varoius pre-defined conditions of flow and, in response thereto, ascertaining the values of a plurality of coefficients each of which is associated with a corresponding term in a pre-defined function that characterizes fluid pressure in relation to pulsatile displacement of the wall of the tube; and second, undertaking a continuous monitoring» phase comprised of determining each subsequently occurring pressure value as the pre-defined function of each corresponding pulsatile wall displacement value, and re-initiating the calibration phase at the expiration of pre-defined time intervals which adaptively change based upon current and prior results. Methods, which are particularly useful in conjunction with the disclosed apparatus, for ascertaining systolic and diastolic arterial blood pressure values are also disclosed.
Inventors
- 👤 Ted W. Russell
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 21:02
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/021; A61B5/022; A61B5/0235; A61B5/0215; A61B5/02156; A61B2560/00; A61B2560/02; A61B2560/0223
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
16 words
A method for use in determining arterial blood pressure in a subject, comprising the steps of:
Claim 2
Independent Claim
16 words
A method for use in determining arterial blood pressure in a subject, comprising the steps of:
Claim 3
Dependent Claim
133 words
undertaking a calibration phase comprised of the steps of determining blood pressure and arterial displacement values of said subject occurring in response to corresponding arterial blood flow initial conditions, and ascertaining, in response to said determined values, the values of a plurality of coefficients, each of which is associated with a corresponding term in a function that characterizes arterial blood pressures in relation to arterial wall displacements, undertaking a continuous monitoring phase comprised of the steps of measuring subsequently occurring actual arterial wall displacement values, generating at least one corresponding arterial blood pressure value in response to said function and to at least one of each of said actual arterial displacement values, and repeating said calibration phase at the occurrence of any one of a plurality of pre-defined events or at pre-defined times.
Claim 4
Dependent Claim
133 words
undertaking a calibration phase comprised of the steps of determining blood pressure and arterial displacement values of said subject occurring in response to corresponding arterial blood flow initial conditions, and ascertaining, in response to said determined values, the values of a plurality of coefficients, each of which is associated with a corresponding term in a function that characterizes arterial blood pressures in relation to arterial wall displacements, undertaking a continuous monitoring phase comprised of the steps of measuring subsequently occurring actual arterial wall displacement values, generating at least one corresponding arterial blood pressure value in response to said function and to at least one of each of said actual arterial displacement values, and repeating said calibration phase at the occurrence of any one of a plurality of pre-defined events or at pre-defined times.
Claim 5
Dependent Claim
40 words
The method of claim 1 wherein said continuous monitoring phase undertaking step includes the step of varying said times in response to differences between the most recent value and a corresponding prior value of at least one of said coefficients.
Claim 6
Dependent Claim
23 words
The method of claim 2 wherein said generating step includes the step of producing various parameter measurements based upon said generated pressure values.
Claim 7
Dependent Claim
42 words
The method of claim 3 wherein said repeating step includes the steps of: checking various ones of said parameter measurements against corresponding limit values, and repeating said calibration phase whenever at least one of said parameter measurements exceeds its corresponding limit value.
Claim 8
Dependent Claim
117 words
The method of claim 1 wherein said determining step includes the steps of: affixing at least one arterial occluding device to at least one selected limb of a subject, controllably operating said occluding device to non-invasively occlude an artery within said selected limb and thereby establish at least a first one of said arterial blood flow initial conditions, sensing perturbations, in the arterial blood flow through said occluding device, as said device reduces its occlusion at a controlled rate so as to establish other ones of said arterial blood flow initial conditions, and determining, in response to the value of said perturbations, values of arterial wall displacement occurring at each of said arterial blood flow initial conditions.
Claim 9
Dependent Claim
55 words
The method of claim 5 in which said operating step further includes the step of measuring said perturbations through said occluding device and controllably increasing the occlusion produced by said device to a value in excess of that required to eliminate said perturbations, whereby an arterial blood flow initial condition of supra-systolic occlusion is achieved..
Claim 10
Dependent Claim
48 words
The method of claim 6 in which said measuring step includes the steps of: attaching a pneumatic cuff around the selected limb, inflating the cuff to an appropriate pressure, and sensing pulsatile perturbations occurring in the air contained in the cuff and attributable to pulsatile arterial blood flow.
Claim 11
Dependent Claim
122 words
The method of claim 7 further comprising the steps of: attaching a relatively high pressure occlusive pneumatic cuff around the selected limb and a low pressure waveform sensor cuff around the same or a different limb of the subject, controllably inflating the occlusive cuff first to said supra-systolic and then deflating the occlusive cuff to sub-diastolic in order to produce various ones of said arterial blood flow initial conditions, inflating said low pressure waveform sensor cuff to an appropriate pressure, and measuring the relative displacement of the arterial wall attributable to the arterial blood flow occurring for various ones of said initial conditions as a function of the simultaneously occurring pulsatile variation in the pressure of said low pressure waveform sensor cuff.
Claim 12
Dependent Claim
85 words
The method of claim 8 further comprising the steps of: securing the high pressure occulsive cuff around one limb of the subject, and securing the low pressure waveform sensor cuff either around the same limb at a location situated distally from the high pressure cuff or around a different limb of the subject, inflating the low pressure waveform sensor cuff to the appropriate pressure, and maintaining the pressure of the low pressure waveform sensor cuff substantially constant during deflation of the high pressure occlusive cuff.
Claim 13
Dependent Claim
93 words
The method of claim 7 further comprising the steps of: inflating the cuff to a supra-systolic pressure to establish at least said first arterial blood flow initial condition, controllably deflating the cuff and sensing simultaneously occurring pulsatile perturbations in the air contained in the cuff so as to establish the other ones of said arterial blood flow initial conditions, inflating the cuff to an appropriate low pressure, and sensing at least one subsequently occurring pulsatile perturbation in the air contained in the cuff for use in determining said corresponding arterial blood pressure value.
Claim 14
Dependent Claim
81 words
The method of claim 1 wherein the ascertaining step further includes the step of substituting each of a pre-selected plurality of arterial wall displacement values into said function in order to fabricate a table of arterial blood pressure values corresponding to said pre-selected plurality of displacement values, and said generating step further includes the step of using at least one of said actual arterial displacement values to access the table in order to determine an arterial blood pressure value corresponding thereto.
Claim 15
Dependent Claim
26 words
The method of claim 11 wherein the generating step further includes the step of fabricating a sequence of present and previously generated arterial blood pressure values.
Claim 16
Dependent Claim
150 words
Apparatus for determining arterial blood pressure in a subject comprising: means for undertaking a calibration phase comprising means for determining blood pressure and arterial displacement values of said subject occurring in response to corresponding arterial blood flow initial conditions, and means for ascertaining, in response to said determined values, the values of a plurality of coefficients, each of which is associated with a corresponding term in a function that characterizes arterial blood pressures in relation to arterial wall displacements, means for undertaking a continuous monitoring phase comprised of means for measuring subsequently occurring actual arterial wall displacement values, means for generating at least one corresponding arterial blood pressure value in response to said function and to at least one of each of said actual arterial displacement values, and means for repeating said calibration phase at the occurrence of any one of a plurality of pre-defined events or at pre-defined times.
Claim 17
Dependent Claim
150 words
Apparatus for determining arterial blood pressure in a subject comprising: means for undertaking a calibration phase comprising means for determining blood pressure and arterial displacement values of said subject occurring in response to corresponding arterial blood flow initial conditions, and means for ascertaining, in response to said determined values, the values of a plurality of coefficients, each of which is associated with a corresponding term in a function that characterizes arterial blood pressures in relation to arterial wall displacements, means for undertaking a continuous monitoring phase comprised of means for measuring subsequently occurring actual arterial wall displacement values, means for generating at least one corresponding arterial blood pressure value in response to said function and to at least one of each of said actual arterial displacement values, and means for repeating said calibration phase at the occurrence of any one of a plurality of pre-defined events or at pre-defined times.
Claim 18
Dependent Claim
42 words
The apparatus of claim 13 wherein said continuous monitoring phase undertaking means is further comprised of means for varying said times in response to differences between the most recent value and a corresponding prior value of at least one of said coefficients.
Claim 19
Dependent Claim
25 words
The apparatus of claim 14 wherein said generating means is further comprised of means for producing various parameter measurements based upon said generated pressure values.
Claim 20
Dependent Claim
45 words
The apparatus of claim 15 wherein said repeating means is comprised of: means for checking various ones of said parameter measurements against corresponding limit values, and means for repeating said calibration phase whenever at least one of said parameter measurements exceeds its corresponding limit value.
Claim 21
Dependent Claim
114 words
The apparatus of claim 13 wherein said determining means is comprised of: means for occluding an artery situated in a selected limb of a subject, means for controllably operating said occluding.means to non-invasively occlude said artery and thereby establish at least a first one of said arterial blood flow initial conditions, means for sensing perturbations, in the arterial blood flow through said occluding means, as said occluding.means reduces its occlusion at a controlled rate so as to establish other ones of said arterial blood flow initial conditions, and means for determining, in response to the value of said perturbations, values of arterial blood pressure occurring at each of said arterial blood flow initial conditions.
Claim 22
Dependent Claim
56 words
The apparatus of claim 17 in which said operating means is comprised of: means for measuring said perturbations through said occluding means and controllably increasing the occlusion produced by said occluding means to a value in excess of that required to eliminate said perturbations, whereby an arterial blood flow initial condition of supra-systolic occlusion is achieved.
Claim 23
Dependent Claim
45 words
The apparatus of claim 18 further comprising: a pneumatic cuff attached around the selected limb, means for inflating the cuff to an appropriate pressure, and means for sensing pulsatile perturbations occurring in the air contained in the cuff and attributable to pulsatile arterial blood flow.
Claim 24
Dependent Claim
126 words
The apparatus of claim 19 further comprising: a relatively high pressure occlusive pneumatic cuff attached around the selected limb and a low pressure waveform sensor cuff attached around the same or a different limb of the subject, means for controllably inflating the occlusive cuff first to said supra-systolic and then deflating the occlusive cuff to sub-diastolic in order to produce various ones of said arterial blood flow initial conditions, means for inflating said low pressure waveform sensor cuff to an appropriate pressure, and means for measuring the relative displacement of the arterial wall attributable to the arterial blood flow occurring for various ones of said initial conditions as a function of the simultaneously occurring pulsatile variation in the pressure of said low pressure waveform sensor cuff.
Claim 25
Dependent Claim
88 words
The apparatus of claim 20 wherein the high pressure occlusive cuff is secured around the selected limb and the low pressure waveform sensor cuff is secured either around the same limb at a location situated distally from the high pressure occlusive cuff or around a different limb of the subject, and further comprising means for inflating the low pressure waveform sensor cuff to the appropriate pressure and thereafter maintaining the pressure of the low pressure waveform sensor cuff substantially constant during deflation of the high pressure occulsive cuff.
Claim 26
Dependent Claim
95 words
The apparatus of claim 19 further comprising: means for inflating the cuff to a supra-systolic pressure to establish at least said first arterial blood flow initial condition, means for controllably deflating the cuff and'sensing simultaneously occurring pulsatile perturbations in the air contained in the cuff so as to establish the other ones of said arterial blood flow initial conditions, means for inflating the cuff to an appropriate low pressure, and means for sensing a subsequentally occurring pulsatile perturbation in the air contained in the cuff for use in determining said corresponding arterial blood pressure value.
Claim 27
Dependent Claim
79 words
The apparatus of claim 13 wherein the ascertaining means is comprised of means for substituting each of a pre-selected plurality of arterial wall displacement values into said function in order to fabricate a table of arterial blood pressure values corresponding to said pre-selected plurality of displacement values, and said generating means further comprises means for accessing the table, using at least one of said actual arterial displacement values, in order to determine a generated blood pressure value corresponding thereto.
Claim 28
Dependent Claim
24 words
The apparatus of claim 23 wherein the generating means comprises means for fabricating a sequence of present and previously generated arterial blood pressure values.
Claim 29
Independent Claim
158 words
A method for use in determining arterial blood pressure in a subject, comprising the steps of: undertaking a calibration phase comprised of the steps of determining blood pressure values and values of a physiologic parameter of said subject related to blood pressure both values occurring in response to corresponding cardiovascular blood flow initial conditions, and ascertaining, in response to said determined values, the values of a plurality of coefficients, each of which'is associated with a corresponding term in a function that characterizes arterial blood pressure in relation to said physiologic parameter, undertaking a continuous monitoring phase comprised of the steps of measuring subsequently occurring actual values of said physiologic parameter, generating at least one corresponding arterial blood pressure value in response to said function and to at least one of each of said actual physiologic parameter values, and repeating said calibration phase at the occurrence of any one of a plurality of pre-defined events or at pre-defined times.
Claim 30
Independent Claim
158 words
A method for use in determining arterial blood pressure in a subject, comprising the steps of: undertaking a calibration phase comprised of the steps of determining blood pressure values and values of a physiologic parameter of said subject related to blood pressure both values occurring in response to corresponding cardiovascular blood flow initial conditions, and ascertaining, in response to said determined values, the values of a plurality of coefficients, each of which'is associated with a corresponding term in a function that characterizes arterial blood pressure in relation to said physiologic parameter, undertaking a continuous monitoring phase comprised of the steps of measuring subsequently occurring actual values of said physiologic parameter, generating at least one corresponding arterial blood pressure value in response to said function and to at least one of each of said actual physiologic parameter values, and repeating said calibration phase at the occurrence of any one of a plurality of pre-defined events or at pre-defined times.
Claim 31
Dependent Claim
50 words
The method of claim 25 wherein either the determining or. measuring steps includes the step of detecting the physiologic parameter through any non-invasive means or through perivascular invasive means, and wherein the physiologic parameter is proportional to arterial wall displacement, arterial blood flow, arterial blood volume or arterial blood velocity.
Claim 32
Dependent Claim
27 words
The method of claim 26 wherein the detecting step further includes the step of sensing said physiologic parameter through non-invasive strain gage plethysmography or electrical impedance plethysmography.
Claim 33
Dependent Claim
23 words
The method of claim 26 wherein the detecting step further includes the step of sensing said physiologic parameter acoustically, optically or through ultrasound.
Claim 34
Dependent Claim
39 words
The method of claim 26 wherein said continuous monitoring phase further includes the step of varying said times in response to differences between the most recent value and a corresponding prior value of at least one of said coefficients.
Claim 35
Dependent Claim
59 words
The method of claim 29 wherein said generating step includes the step of producing various parameter measurements based upon said generated pressure values, and said repeating step includes the steps of: checking various ones of said parameter measurements against corresponding limit values, and repeating said calibration phase whenever at least.one of said parameter measurements exceeds its corresponding limit value.
Claim 36
Dependent Claim
82 words
The method of claim 26 wherein the ascertaining step further includes the step of substituting each of a pre-selected plurality of said physiologic parameter values into said function in order to fabricate a table of arterial blood pressure values corresponding to said pre-selected plurality of physiologic parameter values, and said generating step further includes the step of using at least one of said actual physiologic parameter values to access the table in order to determine an arterial blood pressure value corresponding thereto.
Claim 37
Dependent Claim
26 words
The method of claim 30 wherein the generating step further includes the step of fabricating a sequence of present and previously generated arterial blood pressure values.
References Cited (Backward Citations)
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