EP2053964A2 - Procédé et appareil pour l'évaluation continue d'un paramètre cardiovasculaire au moyen du temps de propagation et de la forme d'onde du pouls artériel. - Google Patents

Procédé et appareil pour l'évaluation continue d'un paramètre cardiovasculaire au moyen du temps de propagation et de la forme d'onde du pouls artériel.

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Publication number
EP2053964A2
EP2053964A2 EP07840391A EP07840391A EP2053964A2 EP 2053964 A2 EP2053964 A2 EP 2053964A2 EP 07840391 A EP07840391 A EP 07840391A EP 07840391 A EP07840391 A EP 07840391A EP 2053964 A2 EP2053964 A2 EP 2053964A2
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Prior art keywords
propagation time
input signal
arterial
estimate
measurement
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EP07840391A
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German (de)
English (en)
Inventor
Feras S. Hatib
Charles R. Mooney
Luchy D. Roteliux
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Edwards Lifesciences Corp
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Edwards Lifesciences Corp
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Priority claimed from US11/593,247 external-priority patent/US8905939B2/en
Priority claimed from US11/774,449 external-priority patent/US20080015451A1/en
Application filed by Edwards Lifesciences Corp filed Critical Edwards Lifesciences Corp
Publication of EP2053964A2 publication Critical patent/EP2053964A2/fr
Withdrawn legal-status Critical Current

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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
    • A61B5/021—Measuring pressure in heart or blood vessels
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7271—Specific aspects of physiological measurement analysis
    • A61B5/7278—Artificial waveform generation or derivation, e.g. synthesising signals from measured signals
    • 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
    • A61B5/02007—Evaluating blood vessel condition, e.g. elasticity, compliance
    • 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
    • A61B5/02028—Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
    • 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
    • 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
    • A61B5/021—Measuring pressure in heart or blood vessels
    • A61B5/02108—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics
    • A61B5/02125—Measuring pressure in heart or blood vessels from analysis of pulse wave characteristics of pulse wave propagation time
    • 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
    • A61B5/021—Measuring pressure in heart or blood vessels
    • A61B5/0215—Measuring pressure in heart or blood vessels by means inserted into the body
    • 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
    • A61B5/026—Measuring blood flow
    • A61B5/0285—Measuring or recording phase velocity of blood waves
    • 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
    • A61B5/026—Measuring blood flow
    • A61B5/029—Measuring or recording blood output from the heart, e.g. minute volume
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
    • A61B5/14551—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters for measuring blood gases
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7235—Details of waveform analysis
    • A61B5/7264—Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/04—Measuring blood pressure
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/06—Measuring blood flow
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/48—Diagnostic techniques
    • A61B8/488—Diagnostic techniques involving Doppler signals
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/053—Measuring electrical impedance or conductance of a portion of the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/053—Measuring electrical impedance or conductance of a portion of the body
    • A61B5/0535—Impedance plethysmography

Definitions

  • the invention relates generally to a system and method for hemodynamic monitoring. More particularly, the invention relates to a system and method for estimation of at least one cardiovascular parameter, such as vascular tone, arterial compliance or resistance, stroke volume (SV), cardiac output (CO), etc., of an individual using a measurement of an arterial pulse pressure propagation time and a waveform.
  • cardiovascular parameter such as vascular tone, arterial compliance or resistance, stroke volume (SV), cardiac output (CO), etc.
  • CO Cardiac output
  • SV represents the stroke volume and I IR represents the heart rate.
  • the SV is typically measured in liters and the HR is typically measured in beats per minute, although other units of volume and time may be used.
  • liquation 1 expresses that the amount of blood the heart pumps out over a unit of time (such as a minute) is equal to the amount it pumps out on every beat (stroke) times the number of beats per time unit.
  • the HR is easy to measure using a wide variety of instruments
  • the calculation of CO usually depends on some technique for estimating the SV.
  • any method that directly yields a value for CO can be used to determine the SV by dividing by the HR.
  • Estimates of CO or SV can then be used to estimate, or contribute to estimating, any parameter that can be derived from either of these values.
  • One invasive method to determine CO is to mount a flow-measuring device on a catheter, and then to thread the catheter into the subject and to maneuver it so that the device is in or near the subject's heart.
  • Some such flow-measuring devices inject either a bolus of material or energy (usually heat) at an upstream position, such as in the right atrium, and determine flow based on the characteristics of the injected material or energy at a downstream position, such as in the pulmonary artery.
  • Patents that disclose implementations of such invasive techniques include:
  • thermo-dilution relies on assumptions such as uniform dispersion of the injected heat that affects the accuracy of the measurements depending on how well they are fulfilled.
  • introduction of an instrument into the blood flow may affect the value (for example, flow rate) that the instrument measures. Therefore, there has been a long-standing need for a method of determining CO that is both non-invasive (or at least as minimally invasive as possible) and accurate.
  • PCM pulse contour method
  • DOC L(T 5819 PC I chamber") parameters are used to construct a linear or non-linear hemodynamic model of the aorta. Jn essence, blood How is analogized to a flow of electrical current in a circuit in which an impedance is in series with a parallel-connected resistance and capacitance (compliance).
  • the three required parameters of the model are usually determined either empirically, through a complex calibration process, or from compiled "anthropometric" data, that is, data about the age, sex, height, weight, etc., of other patients or test subjects.
  • U.S. Patent No. 5,400,793 (Wesseling, 28 March 1995) and U.S. Patent No. 5,535,753 (Petrucelli et al., 16 July 1996) are representative of systems that utilize a Windkesscl circuit model to determine CO.
  • Many extensions to the simple two-element Windkessel model have been proposed in hopes of better accuracy.
  • CO MAP*C / tau (Equation 3) where MAP is mean arterial pressure, 1au is an exponential pressure decay constant, and C, like K, is a scaling factor related to arterial compliance K.
  • vascular tone can be reliably estimated using the shape characteristics of the arterial pulse pressure waveform in combination with a measure of the pressure dependant vascular compliance and the patient's anthropometric data such as age, gender, height, weight and body surface area (BSA): U.S. Published Patent No. 2005/0124904 Al (Luchy Roteliuk, 09 June 2005, "Arterial pressure-based automatic determination of a cardiovascular parameter").
  • the vascular tone is computed as a function of a combination of parameters using a multivariate regression model with the following general form: [00024]
  • K ⁇ n , ⁇ T2 ,... ⁇ Tk , ⁇ P ⁇ , ⁇ P2 ,... ⁇ Pk ,C ⁇ P), BSA,Age,G..) (Equation 6 ) where K is vascular tone (the calibration factor in equations 4 and 5); X is a mulliregression statistical model; ⁇ i r • . • ⁇ u are the 1 -st to k-th order lime domain statistical moments of the arterial pulse pressure waveform; ⁇ ip... ⁇ k p are the J -st to k-th order pressure weighted statistical moments of the arterial pulse pressure waveform;
  • PCl C(P) is a pressure dependent vascular compliance computed using methods proposed by Langwoulers ct al 1984 ("The Static Elastic Properties of 45 Human Thoracic and 20 Abdominal Aortas in vitro and the Parameters of a New Model," J. Biomechanics, Vol. 17, No. 6, pp. 425-435, 1984); BSA is a patient's body surface area (function of height and weight); Age is a patient's age; and G is a patient's gender.
  • the predictor variables set for computing the vascular tone factor K, using the multivariate model ⁇ were related to the "true" vascular tone measurement, determined as a function of CO measured through thermo-dilution and the arterial pulse pressure, for a population of test or reference subjects. This creates a suite of vascular tone measurements, each of which is a function of the component parameters of ⁇ .
  • the multivariate approximating function is then computed, using known numerical methods, that best relates the parameters of ⁇ to a given suite of CO measurements in some predefined sense.
  • ⁇ polynomial multivariate fitting function is used to generate the coefficients of the polynomial that gives a value of ⁇ for each set of the predictor variables.
  • the multivariate model has the following general form:
  • a n arc the coefficients of the polynomial niulliregression model, and X arc the model's predictor variables:
  • Figure 1 illustrates an example of two blood pressure curves representing two different arterial pressure measurements received from a subject according to an embodiment of the invention.
  • Figure 2 illustrates an example of an Electrocardiogram measurement (ECG) and a blood pressure measurement received from a subject according to an embodiment of the invention.
  • ECG Electrocardiogram measurement
  • FIG. 3 is a graph illustrating the relationship between the arterial pulse pressure propagation time and the arterial compliance according to an embodiment of the invention.
  • Figure 4 is a graph illustrating the relationship between the pulse pressure propagation time and vascular tone on patients recovering from cardiac arrest according to an embodiment of the invention.
  • Figures 5-6 are graphs illustrating the correlation between the pulse pressure propagation time and vascular tone for different hemodynamic conditions of the subjects according to several embodiments of the invention.
  • Figures 7-9 are graphs illustrating the correlation between the CO computed using the pulse pressure propagation time, Continuous Cardiac Output (CCO) and CO values measured by thermodilution bolus measurements (TD-CO) for different hemodynamic states of the subjects according to several embodiments of the invention.
  • CO Continuous Cardiac Output
  • TD-CO thermodilution bolus measurements
  • Figure 10 is a graph showing the relationship between the CO estimated using the arterial pressure propagation time according to several embodiments of the invention and CO estimated using the arterial pulse pressure signal
  • Figure 1 1 is a block diagram showing an exemplary system used to execute the various methods described herein according to several embodiments of the invention.
  • Figure 12 is a flow chart showing a method according to an embodiment of the invention.
  • One embodiment of the invention provides a method for determining a cardiovascular parameter including receiving an input signal corresponding to an arterial blood pressure measurement over an interval that covers at least one cardiac cycle, determining a propagation time of the input signal, determining at least one statistical moment of the input signal, and determining an estimate of the cardiovascular parameter using the propagation lime and the at least one statistical moment.
  • One embodiment of the invention provides an apparatus for determining a cardiovascular parameter including a processing unit to receive an input signal corresponding to an arterial blood pressure measurement over an interval that covers at least one cardiac cycle, determine a propagation time of the input signal, determine at least one statistical moment of the input signal and determine an estimate of the cardiovascular parameter using the propagation time and the at least one statistical moment.
  • the invention involves the determination of a cardiac value, such as a stroke volume (SV), and/or a value derived from the SV such as cardiac output (CO), using the arterial pulse pressure propagation time.
  • a cardiac value such as a stroke volume (SV)
  • CO cardiac output
  • the arterial pulse pressure propagation time may be measured by using arterial pressure waveforms or waveforms that are proportional to or derived from the arterial pulse pressure, electrocardiogram measurements, bioimpedance measurements, other cardiovascular parameters, etc. These measurements may be made with an invasive, non-invasive or minimally invasive instrument or a combination of instruments.
  • the invention may be used with any type of subject, whether human or animal.
  • Figure 1 illustrates an example of two blood pressure curves representing two different arterial pressure measurements received from a subject.
  • the top curve represents a central arterial pressure measurement detected from the subject's aorta and the bottom curve represents a measurement detected from the subject's radial artery.
  • the pulse pressure propagation time (t piop ) can be measured as the transit time between the two arterial pressure measurements.
  • the rationale of using the pulse pressure propagation time for hemodynamic measurements is based on a basic principle of cardiovascular biomechanics.
  • the pulse pressure propagation time can be measured invasively or non-invasivcly at several different locations on the pressure waveform (or any other waveform related to the pressure waveform). In the example shown on Figure 1 , the pulse pressure propagation time may be measured by using two different arterial pressure measurements, for example, one reference measurement from the aorta and one peripheral measurement from the radial artery.
  • FIG. 2 illustrates an example of using an electrocardiogram signal as a reference signal for the propagation time measurement.
  • the lop curve represents an electrocardiogram (ECG) signal detected with electrodes placed near the subject's heart and the bottom curve represents an arterial pressure measurement
  • the arterial pulse pressure propagation time (l piO p) may be measured by using the transit time between the ECG signal and the peripheral arterial pressure.
  • a transthoracic bioimpedance measurement could be used as a reference site, and the propagation time could be measured as a transit time versus a peripheral measurement derived from or proportional to the arterial blood pressure.
  • the arterial pulse pressure propagation time provides an indirect measure of the physical (i.e., mechanical) properties of a vessel segment between the two recording sites. These properties include primarily the elastic and geometric properties of the arterial walls.
  • FIG. 3 illustrates an example where the pulse pressure propagation time increases with increasing arterial compliance (C).
  • the pulse pressure propagation time (t prop ) can be represented as a function of arterial compliance (C), i.e.,
  • the arterial pulse pressure propagation time can therefore be used as a simple measure to estimate the arterial compliance.
  • the propagation time can be used as a separate measure to assess a patient's vascular status or can be used in a pulse contour cardiac output algorithm along with other parameters to account for the effects of vascular compliance, vascular resistance and vascular tone.
  • the arterial pulse pressure propagation lime is measured using an
  • this measurement may include the average arterial compliance between the measurement sites and may not reflect the pressure dependence of the arterial compliance.
  • V is the baseline volume.
  • the arterial compliance (C) may be defined as the ratio of the incremental change in volume (dV) resulting from an incremental change in pressure (dP), i.e.,
  • L is the vascular length between the two recording sites and t p iop is the arterial pulse pressure propagation time.
  • the arterial compliance can be represented as:
  • scaling factor ⁇ is a function, which depends on the blood density, the effective vascular distance between the two recording sites and the
  • the arterial pulse pressure propagation time can be used in a number of different ways.
  • the pulse pressure propagation time may be used as an input to a hemodynamic model based on the standard deviation of the arterial pulse pressure to evaluate the dynamic changes in the arterial pressure created by the systolic ejection.
  • the CO can be represented as a function of the standard deviation of the arterial pulse pressure as follow:
  • K is a scaling factor proportional Io the arterial compliance
  • std(P) is the standard deviation of the arterial pulse pressure
  • HR is the heart rate
  • MAP is the mean arterial pressure
  • ⁇ is an exponential pressure decay constant
  • C is a scaling factor related to arterial compliance.
  • K is a measure equal to vascular compliance. If we substitute the scaling factor K in equation 17 for the compliance as given in equation 16, CO can be computed using the standard
  • n is the total number of samples
  • P(k) is the instantaneous pulse pressure
  • P avg is the mean arterial pressure.
  • the mean arterial pressure can be defined as:
  • Figure 4 is a graph illustrating the relationship between the square of the arterial pulse pressure propagation time and the scaling factor K of patients during recovery from cardiac bypass surgery.
  • Figure 4 plots ten (10) averaged data points from ten (10) different patients.
  • the arterial pulse pressure propagation time has been calculated as a transit time between the ECG signal and the radial arterial pressure.
  • the data shown in figure 4 illustrates that the K scaling factors of equation 17 can be effectively estimated using the arterial pulse pressure propagation time as given by equation 16.
  • FIGS 5 and 6 are graphs illustrating the correlation between the arterial pulse pressure propagation time and the K scaling factor of equation 17 for different hemodynamic states of two subjects. Both trends correspond to animal data taken from experiments using porcine animal models. These figures show identical trends of the scaling factor K and the square of the pulse pressure propagation time. The data on figures 5 and 6 illustrate that the K or the C scaling factors of equations 17 and 18 can be effectively estimated using the arterial pulse pressure propagation time. f00083
  • Any known, independent CO technique may be used to determine this relationship, whether invasive, for example, thcrmodilution, or non-invasive, for example, trans-esophagcal echocardiography (TEE) or bio-impedance measurement.
  • TEE trans-esophagcal echocardiography
  • the invention provides continuous trending of CO between intermittent measurements such as TD or TEE.
  • 7639 1 DOC ] CC-5819 PC 1 can be made in the femoral artery. As such, even where an invasive technique is used to determine ⁇ , the invention as a whole is still minimally invasive in that any catheterization may be peripheral and temporary. f00087] ⁇ s discussed above, rather than measure arterial blood pressure directly, any other input signal may be used that is proportional to blood pressure. This means that calibration may be done at any or all of several points in the calculations.
  • ⁇ depends mainly of the physical vascular volume between the two recording sites.
  • the effective length (L) and the effective volume (V) between the two recording sites can not be known.
  • vascular branching and the patient to patient differences arc two main reasons why the effective physical vascular volume between the two recording sites can not be known.
  • this physical volume is proportional to the patient's anthropometric parameters and Iherefore it can be estimated indirectly using the patient's anthropometric parameters.
  • the anthropometric parameters may be derived from various parameters such as the measured distance (1) between the two recording sites, patient's weight, patient's
  • all the anthropometric parameters for example, the distance (1) between the two recording sites, patient's weight, patient's height, patient's gender, patient's age and patient's bsa, may be used to compute y. Additional values are preferably also included in the computation to take other characteristics into account.
  • the heart rate HR (or period of R- waves) may be used.
  • H is the patient's height
  • W is the patient's weight
  • BSA is the patient's bsa
  • Age is the patient's age
  • G is the patient's gender
  • HR is the patient's heart rate
  • FM is a multivariate model.
  • the predictor variables set for computing ⁇ , using the multivariate model Y are related to the "true" vascular compliance measurement, determined as a function of CO measured through thermo-dilution and the arterial pulse pressure, for a population of test or reference subjects. This creates a suite of compliance measurements, each of which is a function of the component parameters of Y M -
  • vascular tone is a hemodynamic parameter used to describe the combined effect of vascular compliance and peripheral resistance.
  • shape characteristics of the arterial pressure waveform in combination with patients anthropometric data and other cardiovascular parameters were used to estimate vascular tone (see Roteliuk, 2005, "Arterial pressure-based automatic determination of a cardiovascular parameter").
  • the arterial pulse pressure propagation time can also be used to estimate vascular tone.
  • the arterial pulse pressure propagation time can be used as an independent term to a multivariate regression model to continuously estimate vascular tone.
  • the arterial pulse pressure propagation lime can be used in combination with the shape information of the arterial pulse pressure waveform to estimate the vascular tone.
  • the higher order shape sensitive arterial pressure statistical moments and the pressure-weighted time moments may be used as predictor variables in the multivariate model along with the arterial pulse pressure propagation time. Additional values are preferably also included in the computation to take other characteristics into account.
  • the heart rate HR (or period of R-waves), the body surface area BSA, as well as a pressure dependent non-linear compliance value C(P) may be calculated using a known method such as described by Langwouters, which computes compliance as a polynomial function of the pressure waveform and the patient's age and sex.
  • K is vascular tone
  • X is a multiregression statistical model
  • t pro ⁇ is the arterial pulse pressure propagation time
  • ⁇ - - .JJ-ki are the 1 -st to k-th order time domain statistical moments of the arterial
  • ⁇ p... ⁇ i c p are the 1-st to k-th order pressure weighted statistical moments of the
  • 7619 1 DOC I CC-5819 PC I C(P) is the pressure dependent vascular compliance as defined by Langwoutcrs ct al. ("The Static Elastic Properties of 45 Human Thoracic and 20 Abdominal Aortas in vitro and the Parameters of a New Model," J. Biomechanics, Vol. 17, No. 6, pp. 425-435, 1984); BSA is the patient's body surface area (function of height and weight); Age is the patient's age; and Gender is the patient's gender.
  • thermo-dilulion may be used to determine CO, HR and S Vest for a population of test or reference subjects. For each subject, anthropometric data such as age, weight, BSA, height, etc. can also be recorded. This creaies a suite of CO measurements, each of which is a function (initially unknown) of the component parameters of K. An approximating function can therefore be computed, using known numerical methods, that best relates the
  • a standard multivariate fitting routine is used to generate the coefficients of a polynomial that gave a value of K for each set of parameters t prop ,
  • K is computed as follows:
  • the pulse pressure propagation time may be used as an independent method to estimate CO. That is, the arterial pulse pressure propagation time is independently proportional to SV, as shown below:
  • the scaling factor K p can be estimated using a direct calibration, for example, using a known CO value from a bolus thcrmo-dilution measurement or other gold standard CO measurement.
  • Figures 7-9 are graphs illustrating the correlation between the CO computed using the pulse pressure propagation time as shown in equation 30 (COprop), Continuous Cardiac Output (CCO) and CO values measured by intermittent thermodilution bolus measurements (ICO).
  • COprop Continuous Cardiac Output
  • ICO continuous thermodilution bolus measurements
  • CCO and ICO are measured using the Vigilance monitor manufactured by Edwards Lifesciences of Irvine, California. The measurements have been performed on animal porcine models in different hemodynamic states of the animals.
  • the scaling factor K p of equation 30 can be determined using any pre-determined function of the propagation time and CO or SV. Any independent CO technique may be used to determine this relationship, whether invasive, for example, thermo-dilution, or non-invasive, for example, trans-esophageal echocardiography (TEE) or bio-impedancc measurement.
  • TEE trans-esophageal echocardiography
  • bio-impedancc measurement The invention provides continuous trending of CO between intermittent measurements such as TD or TKE.
  • the non-invasive techniques to measure the propagation time can include, but are not limited to: ECG, non-invasive arterial blood pressure measurements, bio-impedance measurements, optical pulse oximetry measurements, Doppler ultrasound measurements, or any other measurements derived from or proportional to them or any combination of them (for example: using Doppler ultrasound pulse velocity measurement to measure the reference signal near the heart and using a bio-impedance measurement to measure the peripheral signal ... etc).
  • the scaling factor K p depends mainly on blood viscosity and the physical vascular distance and volume between the two recording sites.
  • the effective length (L) and the effective volume (V) between the two recording sites can not be known.
  • Vascular branching and the patient to patient differences are two main reasons why the effective physical vascular volume between the two recording sites can not be known.
  • the physical volume may be proportional to the patient's anthropometric parameters and therefore it can be estimated indirectly using the patient's anthropometric parameters.
  • the anthropometric parameters may be derived from various parameters such as the
  • L is the measured distance between the two recording sites
  • H is the patient's height
  • W is the patient's weight
  • BSA is the patient's bsa
  • Age is the patient's age
  • G is the patient's gender
  • M is a multivariate linear regression model.
  • the predictor variables set for computing K p are related to the "true" CO measurement, determined as a function of the propagation time, where CO is measured through thermo-dilution, for a population of test or reference subjects. This creates a suite of measurements, each of which is a function of the component parameters of M.
  • the multivariate approximating function is then computed using numerical methods that best relates the parameters of M to a given suite of CO measurements in some predefined sense. ⁇ polynomial multivariate fitting function is used to generate the
  • the multivariate model has the following equation:
  • Figure 10 is a graph showing the relationship between the CO estimated using equation 17 (CO st( j on the x-axis) and CO estimated using equation 30 (CO p i o p on the y-axis) from a series of animal experiments.
  • the data shows CO measurements from a total of ten ( 10) pigs. Three (3) selected data points from each pig are used for the graph. In order to cover a wide CO range, each selected data point corresponds to a different hemodynamic state of the pig: vasodilated, vasoconstrictcd and hypovolemic slates, respectively.
  • the proportionality shown in figure 10 is experimental proof of the effectiveness and the reliability of using the propagation time to estimate CO.
  • FIG. 1 is a block diagram showing an exemplary system used to execute the various methods described herein.
  • the system may include a patient 100, a pressure transducer 201, a catheter 202, ECG electrodes 301 and 302, signal conditioning units 401 and 402, a multiplexer 403, an analog-to-digital converter 405 and a computing unit 500.
  • the computing unit 500 may include a patient specific data module 501 , a scaling factor module 502, a moment module 503, a standard deviation module 504, a propagation time module 505, a stroke volume module 506, a cardiac output module 507, a heart rate module 508, an input device 600, an output device 700, and a heart rate monitor 800.
  • Each unit and module may be implemented in hardware, software, or a combination of hardware and software.
  • the patient specific data module 501 is a memory module that stores patient data such as a patient's age, height, weight, gender, BS ⁇ , etc. This data may be entered using the input device 600.
  • the scaling factor module 502 receives the patient data and performs calculations to compute the scaling compliance factor. For example, the scaling factor module 502 puts the parameters into the expression given above or into some other expression derived by creating an approximating function that best fits a set of test data.
  • the scaling factor module 502 may also determine the time window [t ⁇ , tf
  • the moment module 503 determines or estimates the arterial pulse pressure higher order statistical time domain and weighted moments.
  • 7619 1 DOC FCC-S8I9 PC I dcviation module 504 determines or estimates the standard deviation of the arterial pulse pressure waveform.
  • the propagation time module 505 determines or estimates the propagation time of the arterial pulse pressure waveform.
  • the scaling factor, the higher order statistical moments, the standard deviation and the propagation time arc input into the stroke volume module 506 to produce a SV value or estimate.
  • a heart rate monitor 800 or software routine 508 (for example, using Fourier or derivative analysis) can be used to measure the patient's heart rate.
  • the SV value or estimate and the patient's heart rate arc input into the cardiac output module 507 to produce an estimate of CO using, for example, the equation CO - SV*HR.
  • any or all of the results, SV, CO, vascular compliance, vascular tone and peripheral resistance may be displayed on the output device 700 (e.g., a monitor) for presentation to and interpretation by a user.
  • the output device 700 may typically be the same as is used by the system for other purposes.
  • the invention further relates to a computer program loadable in a computer unit or the computing unit 500 in order to execute the method of the invention.
  • the various modules 501 -507 may be used to perform the various calculations and perform related method steps according to the invention
  • 7639 1 DOC LCC-5819 PC1 may also be stored as computer-executable instructions on a computer- readable medium in order to allow the invention to be loaded into and executed by different processing systems.

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Abstract

L'invention concerne un procédé et un appareil pour déterminer un paramètre cardiovasculaire comportant la réception d'un signal d'entrée correspondant à une mesure de pression du sang artériel sur un intervalle qui recouvre au moins un cycle cardiaque, la détermination d'un temps de propagation du signal d'entrée, la détermination d'au moins un moment statistique du signal d'entrée, et la détermination d'une estimation du paramètre cardiovasculaire à l'aide du temps de propagation et du ou des moments statistiques.
EP07840391A 2006-07-13 2007-07-11 Procédé et appareil pour l'évaluation continue d'un paramètre cardiovasculaire au moyen du temps de propagation et de la forme d'onde du pouls artériel. Withdrawn EP2053964A2 (fr)

Applications Claiming Priority (4)

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US83073506P 2006-07-13 2006-07-13
US11/593,247 US8905939B2 (en) 2006-07-13 2006-11-06 Method and apparatus for continuous assessment of a cardiovascular parameter using the arterial pulse pressure propagation time and waveform
US11/774,449 US20080015451A1 (en) 2006-07-13 2007-07-06 Method and Apparatus for Continuous Assessment of a Cardiovascular Parameter Using the Arterial Pulse Pressure Propagation Time and Waveform
PCT/US2007/073216 WO2008019207A2 (fr) 2006-07-13 2007-07-11 Procédé et appareil pour l'évaluation continue d'un paramètre cardiovasculaire au moyen du temps de propagation et de la forme d'onde du pouls artériel.

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US20100204590A1 (en) * 2009-02-09 2010-08-12 Edwards Lifesciences Corporation Detection of Vascular Conditions Using Arterial Pressure Waveform Data
US20100268097A1 (en) * 2009-03-20 2010-10-21 Edwards Lifesciences Corporation Monitoring Peripheral Decoupling
JP5432765B2 (ja) * 2009-04-17 2014-03-05 日本光電工業株式会社 血液量測定装置及び血液量測定装置の測定結果の評価方法
JP5330069B2 (ja) * 2009-04-17 2013-10-30 日本光電工業株式会社 血液量測定方法、血液量測定装置及び血液量測定プログラム
US20100331708A1 (en) * 2009-06-29 2010-12-30 Edwards Lifesciences Corporation Monitoring cardiovascular conditions using signal transit times
EP2281504A1 (fr) * 2009-08-04 2011-02-09 Pulsion Medical Systems AG Appareil et procédé pour la détermination d'un paramètre physiologique
JP5850861B2 (ja) * 2010-01-29 2016-02-03 エドワーズ ライフサイエンシーズ コーポレイションＥｄｗａｒｄｓ Ｌｉｆｅｓｃｉｅｎｃｅｓ Ｃｏｒｐｏｒａｔｉｏｎ 心血管系パラメータの決定における不規則な心周期の影響の排除
JP5636731B2 (ja) * 2010-05-10 2014-12-10 オリンパス株式会社 血圧センサシステム及びその血圧計測方法
JP2014087476A (ja) * 2012-10-30 2014-05-15 Nippon Koden Corp 心拍出量測定ユニット
US20160270708A1 (en) * 2013-10-03 2016-09-22 Konica Minolta, Inc. Bio-information measurement device and method therefor
WO2024082231A1 (fr) * 2022-10-20 2024-04-25 深圳迈瑞生物医疗电子股份有限公司 Méthode de surveillance de paramètre cardiovasculaire et dispositif médical associé

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JP2009543609A (ja) 2009-12-10
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AU2007281884A1 (en) 2008-02-14
BRPI0714207A2 (pt) 2012-12-25

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