Arterial pressure-based, automatic determination of a cardiovascular parameter

• US 20090062666A1
• Filed: 10/23/2008
• Published: 03/05/2009
• Est. Priority Date: 12/05/2003
• Status: Active Grant

• Current Assignee: Edwards Lifesciences Corporation
• Original Assignee: Edwards Lifesciences Corporation
• Inventors: Roteliuk, Luchy
• Granted Patent: US 7,967,757 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/029 Measuring or recording blood output from the heart, e.g. minute volume A61B8/065 takes precedence
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

One or more cardiovascular parameters is estimated as a function of the arterial pressure waveform, in particular, using at least one statistical moment of a discrete representation pressure waveform having an order greater than one. Arterial compliance, the exponential pressure decay constant, vascular resistance, cardiac output, and stroke volume are examples of cardiovascular parameters that can be estimated using various aspects of the invention. In one embodiment of the invention, not only are the first four moments (mean, standard deviation, skewness, and kurtosis) of the pressure waveform used to estimate the cardiovascular parameter(s) of interest, but also heart rate, statistical moments of a set of pressure-weighted time values, and certain anthropometric patient measurements such as age, sex, body surface area, etc.

Claims

1. A method for determining a cardiovascular parameter of a subject comprising:

sensing, over a period corresponding to at least one cardiac cycle, an input signal that indicates arterial blood pressure;

computing a set of pressure-weighted time values, each corresponding to the product of a sensing time, relative to an initial time, and arterial pressure at the sensing time; and

estimating the cardiovascular parameter as a function of the set of pressure-weighted time values.

2. A method as in claim 1, in which the cardiovascular parameter is arterial compliance.

3. A method as in claim 2, further comprising:

determining an approximating function relating a set of clinically determined reference measurements to arterial compliance, in which the approximating function is a function of the statistical moment(s) of the pressure-weighted time values and of a set of anthropometric values;

computing the statistical moment(s) of the pressure-weighted time values, as well as measuring the set of anthropometric values of the subject;

estimating the arterial compliance of the subject by evaluating the approximating function with the computed statistical moment(s) of the pressure-weighted time values, as well as with the measure set of anthropometric values of the subject.

4. A method as in claim 1, in which the cardiovascular parameter is vascular resistance.

5. A method as in claim 1, in which the cardiovascular parameter is cardiac output.

6. A method as in claim 1, in which the cardiovascular parameter is stroke volume.

7. A method as in claim 1, in which the cardiovascular parameter is a pressure decay constant.

8. A method as in claim 1, further comprising estimating the cardiovascular parameter as a function of the kurtosis of the pressure-weighted time values.

9. A method as in claim 1, further comprising estimating the cardiovascular parameter as a function of the standard deviation of the pressure-weighted time values.

10. A method as in claim 1, further comprising estimating the cardiovascular parameter as a function of the skewness of the pressure-weighted time values.

11. A method as in claim 1, further comprising:

measuring a predetermined set of anthropometric parameters of the subject; and

estimating the cardiovascular parameter as a function of the measured anthropometric parameters.

12. A method as in claim 1, further comprising:

computing at least two statistical moments not only of the input signal, but also of the set of pressure-weighted time values;

in which the approximating function is a function of the computed statistical moments of both the input signal and of the set of pressure-weighted time values.

13. A method as in claim 1, further comprising:

measuring the subject'"'"'s heart rate;

estimating stroke volume as a function of the product of the estimated arterial compliance and the standard deviation the input signal; and

computing cardiac output value as a function of the product of the estimated stroke volume and the measured heart rate.

14. A system for determining a cardiovascular parameter of a subject comprising:

a processing system sensing, over a period corresponding to at least one cardiac cycle, an input signal that indicates arterial blood pressure;

computer-executable code for computing a set of pressure-weighted time values, each corresponding to the product of a sensing time, relative to an initial time, and arterial pressure at the sensing time; and

for estimating the cardiovascular parameter as a function of the set of pressure-weighted time values.

15. The system of claim 14, wherein the cardiovascular parameter is arterial compliance.

16. The system of claim 15, wherein the computer-executable code is configured to:

determine an approximating function relating a set of clinically determined reference measurements to arterial compliance, in which the approximating function is a function of the statistical moment(s) of the pressure-weighted time values and of a set of anthropometric values;

compute the statistical moment(s) of the pressure-weighted time values, as well as measuring the set of anthropometric values of the subject; and

estimate the arterial compliance of the subject by evaluating the approximating function with the computed statistical moment(s) of the pressure-weighted time values, as well as with the measure set of anthropometric values of the subject.

17. A method as in claim 14, in which the cardiovascular parameter is vascular resistance.

18. A method as in claim 14, in which the cardiovascular parameter is cardiac output.

19. A method as in claim 14, in which the cardiovascular parameter is stroke volume.

20. A method as in claim 14, in which the cardiovascular parameter is a pressure decay constant.