Method and system for system identification of physiological systems

• US 6,340,346 B1
• Filed: 11/26/1999
• Issued: 01/22/2002
• Est. Priority Date: 11/26/1999
• Status: Expired due to Fees

• Current Assignee: TAO Medical Technologies Limited
• Original Assignee: TAO Medical Technologies Limited
• Inventors: Almog, Yael, Toledo, Eran
• Primary Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US09/449,752
• Time in Patent Office: 788 Days
• Field of Search: 600/300, 600/301, 600/304, 600/313, 600/338, 600/351, 600/376, 600/511, 600/481, 600/529, 128/898
• US Class Current: 600/300
• CPC Class Codes: A61B 5/00 Measuring for diagnostic purposes radiation diagnosis A61B6/00; diagnosis by ultrasonic, sonic or infrasonic waves A61B8/00; Identification of persons
• CPC Class Codes: A61B 5/344 Foetal cardiography
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders

Abstract

A system for monitoring a pregnancy in a pregnant woman having a maternal-placenta-fetal system is disclosed. The system comprises (a) at least one monitoring device simultaneously monitoring selected maternal and fetal physiological signals; and (b) a computerized system being in communication with each of the at least one monitoring device for preprocessing the maternal and fetal physiological signals by independently non-linearly or linearly mathematically decomposing the maternal and fetal physiological signals into mathematical constituents thereof and collecting constituents of the mathematical constituents having a highest degree of linearity and/or simplicity, and for using the constituents having the highest degree of linearity and/or simplicity for identifying a mathematical model describing the maternal-placenta-fetal system, and mathematical parameters describing the model.

Claims

1. A method of determining the well being of a placenta in a pregnant woman having a maternal-placenta-fetal system, the method comprising the steps of:

(a) simultaneously monitoring selected maternal and fetal physiological signals;

(b) preprocessing said maternal and fetal physiological signals by independently non-linearly or linearly mathematically decomposing said maternal and fetal physiological signals into mathematical constituents thereof and collecting constituents of said mathematical constituents having a highest degree of linearity and/or simplicity;

(c) using said constituents having said highest degree of linearity and/or simplicity for identifying a mathematical model describing the maternal-placenta-fetal system, and mathematical parameters describing said model; and

(d) determining, according to said mathematical model and said mathematical parameters describing said mathematical model, the well being of the placenta.

2. The method of claim 1, wherein while simultaneously monitoring said selected maternal and fetal physiological signals the pregnant woman is provoked by an external stimulus.

3. The method of claim 1, wherein said physiological signals are selected from the group consisting of ECG, BP, PO₂, PCO₂, blood flow, blood velocity, blood volume, thermal index and respiration.

4. The method of claim 1, wherein said mathematical model is selected from the group consisting of nonparametric models, parametric models, polynominal representation, simple autoregressive model, ARMAX model structure, output error structure, Box-Jenkins model structure, general parametric model structure, state space representation, linear time-varying models, time-invariant model, nonlinear models, nonlinear ARMAX, Wiener kernels model, Korenberg-Billings model and Volterra-Wiener model.

5. The method of claim 1, wherein said step of identifying said mathematical model is effected by identifying a best mathematical model describing the maternal-placenta-fetal system, said best mathematical model is selected out of a plurality of available mathematical models and according to predetermined criteria.

6. The method of claim 1, wherein said model is a linear model.

7. The method of claim 1, wherein said step of preprocessing said maternal and fetal physiological signals includes at least one process selected from the group consisting of:

(i) calculating a maternal heart rate from an inter-beat interval of maternal ECG;

(ii) calculating maternal heart rate from maxima values of maternal blood flow;

(iii) calculating a maternal pulse wave velocity from a delay between R-waves of an ECG and corresponding systoles of blood flow signal;

(iv) calculating maternal contractility from maternal blood flow by determining maximal derivative in a maternal systole stage;

(v) calculating a fetal heart rate from an inter-beat interval of fetal ECG;

(vi) calculating a fetal heart rate from an inter-beat interval of fetal Doppler signal representing fetal heart valve closing;

(vii) calculating a fetal blood flow using ultrasound reflection from a fetal blood vessel; and

(viii) calculating a fetal heart rate from fetal blood flow rate; and

(ix) calculating a fetal blood flow rate using ultrasound reflection from a fetal blood vessel.

8. A method of determining the well being of a fetus in a pregnant woman having a maternal-placenta-fetal system, the method comprising the steps of:

(a) simultaneously monitoring selected maternal and fetal physiological signals;

(b) preprocessing said maternal and fetal physiological signals by independently non-linearly or linearly mathematically decomposing said maternal and fetal physiological signals into mathematical constituents thereof and collecting constituents of said mathematical constituents having a highest degree of linearity and/or simplicity;

(c) using said constituents having said highest degree of linearity and/or simplicity for identifying a mathematical model describing the maternal-placenta-fetal system, and mathematical parameters describing said model; and

(d) determining, according to said mathematical model and said mathematical parameters describing said mathematical model, the well being of the fetus.

9. The method of claim 8, wherein while simultaneously monitoring said selected maternal and fetal physiological signals the pregnant woman is provoked by an external stimulus.

10. The method of claim 8, wherein said physiological signals are selected from the group consisting of ECG, BP, PO₂, PCO₂, blood flow, blood velocity, blood volume, thermal index and respiration.

11. The method of claim 8, wherein said mathematical model is selected from the group consisting of nonparametric models, parametric models, polynominal representation, simple autoregressive model, ARMAX model structure, output error structure, Box-Jenkins model structure, general parametric model structure, state space representation, linear time-varying models, time-invariant model, nonlinear models, nonlinear ARMAX, Wiener kernels model, Korenberg-Billings model and Volterra-Wiener model.

12. The method of claim 8, wherein said step of identifying said mathematical model is effected by identifying a best mathematical model describing the maternal-placenta-fetal system, said best mathematical model is selected out of a plurality of available mathematical models and according to predetermined criteria.

13. The method of claim 8, wherein said model is a linear model.

14. The method of claim 8, wherein said step of preprocessing said maternal and fetal physiological signals includes at least one process selected from the group consisting of:

(i) calculating a maternal heart rate from an inter-beat interval of maternal ECG;

(ii) calculating maternal heart rate from maxima values of maternal blood flow;

(iii) calculating a maternal pulse wave velocity from a delay between R-waves of an ECG and corresponding systoles of blood flow signal;

(iv) calculating maternal contractility from maternal blood flow by determining maximal derivative in a maternal systole stage;

(v) calculating a fetal heart rate from an inter-beat interval of fetal ECG;

(vi) calculating a fetal heart rate from an inter-beat interval of fetal Doppler signal representing fetal heart valve closing;

(vii) calculating a fetal blood flow using ultrasound reflection from a fetal blood vessel; and

(viii) calculating a fetal heart rate from fetal blood flow rate; and

(ix) calculating a fetal blood flow rate using ultrasound reflection from a fetal blood vessel.

15. A method of determining a maternal-fetus relation in a pregnant woman having a maternal-placenta-fetal system, the method comprising the steps of:

(a) simultaneously monitoring selected maternal and fetal physiological signals;

(b) preprocessing said maternal and fetal physiological signals by independently non-linearly or linearly mathematically decomposing said maternal and fetal physiological signals into mathematical constituents thereof and collecting constituents of said mathematical constituents having a highest degree of linearity and/or simplicity;

(c) using said constituents having said highest degree of linearity and/or simplicity for identifying a mathematical model describing the maternal-placenta-fetal system, and mathematical parameters describing said model; and

(d) determining, according to said mathematical model and said mathematical parameters describing said mathematical model, the maternal-fetus relation.

16. The method of claim 15, wherein while simultaneously monitoring said selected maternal and fetal physiological signals the pregnant woman is provoked by an external stimulus.

17. The method of claim 15, wherein said physiological signals are selected from the group consisting of ECG, BP, PO₂, PCO₂, blood flow, blood velocity, blood volume, thermal index and respiration.

18. The method of claim 15, wherein said mathematical model is selected from the group consisting of nonparametric models, parametric models, polynominal representation, simple autoregressive model, ARMAX model structure, output error structure, Box-Jenkins model structure, general parametric model structure, state space representation, linear time-varying models, time-invariant model, nonlinear models, nonlinear ARMAX, Wiener kernels model, Korenberg-Billings model and Volterra-Wiener model.

19. The method of claim 15, wherein said step of identifying said mathematical model is effected by identifying a best mathematical model describing the maternal-placenta-fetal system, said best mathematical model is selected out of a plurality of available mathematical models and according to predetermined criteria.

20. The method of claim 15, wherein said model is a linear model.

21. The method of claim 15, wherein said step of preprocessing said maternal and fetal physiological signals includes at least one process selected from the group consisting of:

(i) calculating a maternal heart rate from an inter-beat interval of maternal ECG;

(ii) calculating maternal heart rate from maxima values of maternal blood flow;

(iii) calculating a maternal pulse wave velocity from a delay between R-waves of an ECG and corresponding systoles of blood flow signal;

(iv) calculating maternal contractility from maternal blood flow by determining maximal derivative in a maternal systole stage;

(v) calculating a fetal heart rate from an inter-beat interval of fetal ECG;

(vi) calculating a fetal heart rate from an inter-beat interval of fetal Doppler signal representing fetal heart valve closing;

(vii) calculating a fetal blood flow using ultrasound reflection from a fetal blood vessel; and

(viii) calculating a fetal heart rate from fetal blood flow rate; and

(ix) calculating a fetal blood flow rate using ultrasound reflection from a fetal blood vessel.

22. A system for monitoring a pregnancy in a pregnant woman having a maternal-placenta-fetal system, the system comprising:

(a) at least one monitoring device simultaneously monitoring selected maternal and fetal physiological signals; and

(b) a computerized system being in communication with each of said at least one monitoring device for preprocessing said maternal and fetal physiological signals by independently non-linearly or linearly mathematically decomposing said maternal and fetal physiological signals into mathematical constituents thereof and collecting constituents of said mathematical constituents having a highest degree of linearity and/or simplicity, and for using said constituents having said highest degree of linearity and/or simplicity for identifying a mathematical model describing the maternal-placenta-fetal system, and mathematical parameters describing said model.

23. The system of claim 22, wherein said physiological signals are selected from the group consisting of ECG, BP, PO₂, PCO₂, blood flow, blood velocity, blood volume, thermal index and respiration.

24. The system of claim 22, wherein said mathematical model is selected from the group consisting of nonparametric models, parametric models, polynominal representation, simple autoregressive model, ARMAX model structure, output error structure, Box-Jenkins model structure, general parametric model structure, state space representation, linear time-varying models, time-invariant model, nonlinear models, nonlinear ARMAX, Wiener kernels model, Korenberg-Billings model and Volterra-Wiener model.

25. The system of claim 22, wherein identifying said mathematical model is effected by identifying a best mathematical model describing the maternal-placenta-fetal system, said best mathematical model is selected out of a plurality of available mathematical models and according to predetermined criteria.

26. The system of claim 22, wherein said model is a linear model.

27. The system of claim 22, wherein preprocessing said maternal and fetal physiological signals includes at least one process selected from the group consisting of:

(i) calculating a maternal heart rate from an inter-beat interval of maternal ECG;

(ii) calculating maternal heart rate from maxima values of maternal blood flow;

(iii) calculating a maternal pulse wave velocity from a delay between R-waves of an ECG and corresponding systoles of blood flow signal;

(iv) calculating maternal contractility from maternal blood flow by determining maximal derivative in a maternal systole stage;

(v) calculating a fetal heart rate from an inter-beat interval of fetal ECG;

(vi) calculating a fetal heart rate from an inter-beat interval of fetal Doppler signal representing fetal heart valve closing;

(vii) calculating a fetal blood flow using ultrasound reflection from a fetal blood vessel; and

(viii) calculating a fetal heart rate from fetal blood flow rate; and

(ix) calculating a fetal blood flow rate using ultrasound reflection from a fetal blood vessel.