SYSTEM AND METHOD FOR MONITORING HEMODYNAMIC STATE

• US 20100312115A1
• Filed: 06/05/2009
• Published: 12/09/2010
• Est. Priority Date: 06/05/2009
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Dentinger, Aaron Mark
• Granted Patent: US 9,204,857 B2
• Time in Patent Office: Days
• US Class Current: 600/450
• CPC Class Codes: A61B 5/02116 of pulse wave amplitude A61B5/02225 takes precedence
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 8/04 Measuring blood pressure

Abstract

A method for continuous non-invasive hemodynamic state monitoring in a subject is provided. The method includes acquiring continuous ultrasound data via an ultrasound transducer attached to the subject. The method also includes estimating continuous arterial waveforms based upon the acquired ultrasound data. The method further includes deriving hemodynamic parameters for each cardiac cycle from the arterial waveforms. The method also includes defining a current hemodynamic state of the subject by setting limits on one or more hemodynamic parameters based upon the variation of these parameters over an initial period of time. The method further includes continuously monitoring a hemodynamic state of the subject. The method further includes comparing a current state for one or more hemodynamic parameters of the subject to previously determined limits for the one or more hemodynamic parameters, and either outputting a trigger signal or alarm to a hemodynamic state monitor in an event that a change is detected in the current state of the one or more hemodynamic parameters or converting the arterial parameters into a continuous estimate of the arterial blood pressure in an event that a change is not detected.

Claims

1. A method for continuous non-invasive hemodynamic state monitoring in a subject comprising:

acquiring continuous ultrasound data via an ultrasound transducer attached to the subject;

estimating a plurality of continuous arterial waveforms based upon the acquired ultrasound data;

deriving hemodynamic parameters for each cardiac cycle from the arterial waveforms;

defining a current hemodynamic state of the subject by setting limits on one or more hemodynamic parameters based upon the variation of these parameters over an initial period of time;

defining an initial biomechanical model of the artery calibrated for the current hemodynamic state that converts arterial waveforms into a continuous estimate of arterial blood pressure;

continuously monitoring the hemodynamic state of the subject based upon the generated hemodynamic parameters from subsequent measurements;

comparing the current state for one or more hemodynamic parameters of the subject to previously determined limits for one or more hemodynamic parameters, and performing either of the following;

outputting a trigger signal or alarm from the hemodynamic state monitor, redefining the current hemodynamic state of the subject by setting new limits for one or more of the hemodynamic parameters based on recent measurements, and calibrating a new biomechanical model for the current hemodynamic state in an event that a change is detected in the current state of one or more hemodynamic parameters;

converting the arterial waveforms into a continuous estimate of the arterial blood pressure using the biomechanical model, and outputting the current hemodynamic parameters, blood pressure estimates, and arterial waveforms in an event that a change in the current state of the one or more hemodynamic parameters is not detected.

2. The method of claim 1, wherein the continuous arterial waveforms comprise arterial area and volumetric flow rate.

3. The method of claim 1, wherein one or more of the hemodynamic parameters comprise a minimum, a maximum, an average value of the arterial waveforms over a heart cycle, or a heart rate derived from a period of the arterial waveforms.

4. The method of claim 1, wherein the hemodynamic parameters are augmented by one or more hemodynamic parameters comprised of heart rate, respiratory rate and oxygenation level from ancillary monitoring devices attached to the subject.

5. The method of claim 1, wherein the hemodynamic parameters are averaged over the respiratory cycle.

6. The method of claim 1, wherein the biomechanical model comprises a non-linear curve of the arterial compliance for converting arterial area into blood pressure.

7. The method of claim 1, wherein the biomechanical model of the artery comprises a static arterial compliance model calibrated for a single hemodynamic state using arterial area measurements from ultrasound data and a reading of the arterial blood pressure of the subject acquired with an automated blood pressure device.

8. The method of claim 1, wherein the biomechanical model of the artery comprises an adaptable arterial compliance model generated by selecting from multiple previously calibrated arterial compliance curves based on a measure of similarity of the current hemodynamic state with the previous hemodynamic states.

9. The method of claim 1, wherein the biomechanical model of the artery comprises an adaptable arterial compliance model generated by averaging multiple previously calibrated arterial compliance curves weighted by a measure of the similarity of the current hemodynamic state with the previous hemodynamic state.

10. The method of claim 1, wherein said subject comprises a living organism.

11. The method of claim 1, further comprising extracting heart rate for each cardiac cycle via an electrocardiograph.

12. The method of claim 1, wherein a change in a state of the one or more hemodynamic parameters comprise a change in values of at least one of diastolic, systolic, and a mean blood pressure.

13. A system for continuous non-invasive hemodynamic state monitoring in a subject comprising:

an ultrasound transducer acoustically coupled to the subject configured to acquire a plurality of ultrasound data;

an ultrasound processor coupled to the ultrasound transducer, the ultrasound processor configured to;

estimate a plurality of arterial parameters based upon the acquired ultrasound data;

derive hemodynamic parameters for each cardiac cycle from the arterial waveforms;

define a current hemodynamic state of the subject by setting limits on one or more hemodynamic parameters based upon the variation of these parameters over an initial period of time;

define an initial biomechanical model of the artery calibrated for the current hemodynamic state that converts arterial waveforms into a continuous estimate of arterial blood pressure;

continuously monitor a hemodynamic state of the subject based upon the generated hemodynamic parameters from subsequent measurements;

compare a current state for one or more hemodynamic parameters of the subject to previously determined limits for one or more hemodynamic parameters, and perform either of the following;

output a trigger signal or alarm from a hemodynamic state monitor, redefining the current hemodynamic state of the subject by setting new limits for one or more of the hemodynamic parameters based on recent measurements, and calibrate a new biomechanical model for the current hemodynamic state in an event that a change is detected in the current state of one or more hemodynamic parameters;

convert the arterial waveforms into a continuous estimate of the arterial blood pressure using the biomechanical model, and output the current hemodynamic parameters, blood pressure estimates, and arterial waveforms in an event that a change in the current state of the one or more hemodynamic parameters is not detected; and

a display coupled to the processor configured to output a measured value of the one or more hemodynamic parameters.

14. The system of claim 13, wherein one or more of the hemodynamic parameters comprise a minimum, maximum, or average value of the arterial waveforms over a heart cycle or a heart rate derived from a period of the arterial waveforms.

15. The system of claim 13, wherein the continuous arterial waveforms comprise arterial area and volumetric flow rate.

16. The system of claim 13, wherein the biomechanical model of the artery comprises a static arterial compliance model calibrated for a single hemodynamic state using arterial area measurements from ultrasound data and a reading of the arterial blood pressure of the subject acquired with an automated blood pressure device.

17. The system of claim 13, wherein the biomechanical model of the artery comprises an adaptable arterial compliance model generated by selecting from multiple previously calibrated arterial compliance curves based on a measure of similarity of the current hemodynamic state with the previous hemodynamic states.

18. The system of claim 13, wherein the biomechanical model of the artery comprises an adaptable arterial compliance model generated by averaging multiple previously calibrated arterial compliance curves weighted by a measure of the similarity of the current hemodynamic state with the previous hemodynamic state.

19. The system of claim 13, wherein said subject comprises a living organism.

20. The system of claim 13, wherein a change in a state of the one or more hemodynamic parameters comprise a change in values of at least one of diastolic, systolic, and a mean blood pressure.

21. The system of claim 13, further consisting of an automated blood pressure device comprising a blood pressure cuff and pressure sensor attached to the subject and a blood pressure processor configured to inflate and deflate the blood pressure cuff, sense oscillations in the back pressure, and estimate the diastolic, mean and systolic blood pressures for calibrating the biomechanical model.