Predictive probe stabilization relative to subject movement

• US 6,366,803 B1
• Filed: 12/23/1999
• Issued: 04/02/2002
• Est. Priority Date: 12/23/1999
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: Agere Systems Guardian Corp. (Broadcom, Inc.)
• Inventors: Fee, Michale Sean
• Primary Examiner(s): Schaetzle, Kennedy
• Application Number:
  US09/470,861
• Time in Patent Office: 831 Days
• Field of Search: 600/424, 600/483, 600/544, 600/300, 600/301, 600/481, 600/484, 600/509, 600/529, 600/534, 600/547, 600/552, 600/587, 600/114, 600/117, 600/118, 128/899, 128/897, 128/898, 128/920, 356/614, 901/9
• US Class Current: 600/509
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: A61B 5/068 using impedance sensors
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: Y10S 128/92 Computer assisted medical diagnostics

Abstract

The present invention provides a method and system to actively or predictively stabilize a probe, such as a microelectrode, relative to movement of the subject. In the preferred embodiments, cardiac and respiratory activities of the subject are measured and utilized to predict subject movement. In the preferred embodiments, a probe is mounted on a manipulator such that the probe moveable in response to a control voltage. A calibrated control voltage is determined from a known probe displacement, such as by measuring probe impedance during a probe oscillation having a known amplitude and frequency. A plurality of control voltage parameters, such as filter coefficients, are then determined from the calibrated control voltage and from a respective measured biological function, such as from an EKG or a thoracic pressure measurement. The control voltage for the probe is then generated from the respective measured biological function and from the respective plurality of control voltage parameters. When more than one measured biological function is utilized, the overall control voltage is a linear superposition of respective intermediate control voltages. The probe is then moved in response to the control voltage, providing stabilization relative to subject movement, and the probe may then be utilized for desired measurements within the subject.

Claims

1. A method for predictive probe stabilization, the probe stabilization relative to movement of a subject, the method comprising:

(a) inserting a probe into the subject, the probe moveable in response to a control voltage;

(b) determining a calibrated control, voltage from a known displacement;

(c) determining a plurality of control voltage parameters from the calibrated control voltage and from a measured biological function of the subject;

(d) generating the control voltage from the measured biological function and from the plurality of control voltage parameters; and

(e) moving the probe within the subject in response to the control voltage.

2. The method of claim 1, further comprising:

(f) performing probe measurements within the subject.

3. The method of claim 1, wherein the measured biological function is an electrocardiogram as a measurement of cardiac function of the subject.

4. The method of claim 1, wherein the measured biological function is thoracic pressure as a measurement of respiratory function of the subject.

5. The method of claim 1, wherein step (d) further comprises:

generating the control voltage as a linear superposition of a first intermediate control voltage determined from a first plurality of control voltage parameters and an electrocardiogram as a first measured biological function, and a second intermediate control voltage determined from a second plurality of control voltage parameters and thoracic pressure as a second measured biological function.

6. The method of claim 1, wherein step (b) further comprises:

measuring an impedance of the probe during a known oscillatory movement having a known amplitude and frequency.

7. The method of claim 1, wherein step (c) further comprises:

determining the plurality of control voltage parameters as a plurality of finite impulse response (FIR) filter coefficients a_i;

determining the plurality of FIR filter coefficients a_i as inverse Fourier transforms of a corresponding plurality of coefficients A(ω

), wherein the plurality of coefficients A(ω

) are determined in a frequency domain from a transfer function;

8. The method of claim 7, wherein step (d) further comprises determining the control voltage V_CONTROL(t) as:

9. The method of claim 7 wherein the plurality of FIR filter coefficients a_i at non-harmonic frequencies of the measured biological function are determined by cubic-spline interpolation.

10. The method of claim 1, wherein probe movement in response to the control voltage is in a direction of the probe axis.

11. The method of claim 1, wherein probe movement in a direction lateral to the probe axis is passive.

12. The method of claim 1, wherein the probe is a microelectrode.

13. The method of claim 1, wherein the probe is a microscopic instrument.

14. The method of claim 1, wherein the probe is a surgical instrument.

15. The method of claim 1, wherein the probe is a fiber-optic scope.

16. The method of claim 1, wherein the probe is a microscope.

17. A system for predictive probe stabilization, the probe stabilization relative to movement of a subject, the system comprising:

a manipulator, the manipulator couplable to a probe, the manipulator operable to move the probe in response to a control voltage; and

a processor, the processor having an output coupled to the manipulator, the processor having a plurality of inputs to receive a measured biological function of the subject and to receive a calibration measurement, wherein the processor includes instructions to determine a calibrated control voltage from a known displacement, to determine a plurality of control voltage parameters from the calibrated control voltage and from a measured biological function of the subject, and to generate the control voltage at the output from the measured biological function and from the plurality of control voltage parameters.

18. The system of claim 17, wherein the processor further comprises:

a multi-channel analog-to-digital converter forming the plurality of inputs;

a digital signal processor; and

a digital-to-analog converter forming the output.

19. The system of claim 17, further comprising:

an electrocardiograph coupled to the subject and coupled to a first input of the plurality of inputs of the processor to generate the measured biological function as an electrocardiogram, as a measurement of cardiac function of the subject.

20. The system of claim 17, further comprising:

a pressure detector coupled to the subject and coupled to a second input of the plurality of inputs of the processor to generate the measured biological function as thoracic pressure, as a measurement of respiratory function of the subject.

21. The system of claim 17, wherein the processor includes further instructions to generate the control voltage as a linear superposition of a first intermediate control voltage determined from a first plurality of control voltage parameters and an electrocardiogram as a first measured biological function, and a second intermediate control voltage determined from a second plurality of control voltage parameters and thoracic pressure as a second measured biological function.

22. The system claim 17, wherein the calibration measurement includes an impedance measurement of the probe during a known oscillatory movement having a known amplitude and frequency.

23. The system of claim 17, wherein the processor includes further instructions to determine the plurality of control voltage parameters as a plurality of finite impulse response (FIR) filter coefficients a_i;

and to determining the plurality of FIR filter coefficients a_i as inverse Fourier transforms of a corresponding plurality of coefficients A(ω

), wherein the plurality of coefficients A(ω

) are determined in a frequency domain from a transfer function;

24. The system of claim 23, wherein the processor includes further instructions to determine the control voltage V_CONTROL(t) as:

25. The system of claim 23 wherein the processor includes further instructions to determine by cubic-spline interpolation the plurality of FIR filter coefficients a;

at non-harmonic frequencies of the measured biological function.

26. The system of claim 17, wherein movement of the manipulator in response to the control voltage is in a direction of the probe axis.

27. The system of claim 17, wherein probe movement in a direction lateral to the probe axis is passive.

28. The system of claim 17, wherein the probe is a microelectrode.

29. The system of claim 17, wherein the probe is a microscopic instrument.

30. The system of claim 17, wherein the probe is a surgical instrument.

31. The system of claim 17, wherein the probe is a fiber-optic scope.

32. The system of claim 17, wherein the probe is a microscope.

33. A system for predictive probe stabilization, the probe stabilization relative to movement of a subject, the system comprising:

a manipulator, the manipulator removably attachable to a probe, the manipulator operable to move the probe in response to a control voltage;

an electrocardiograph coupled to the subject to measure cardiac function as a first measured biological function;

a pressure detector coupled to the subject to measure respiratory function as a second measured biological function; and

a processor, the processor having as a digital-to-analog converter as an output coupled to the manipulator, the processor having a multi-channel analog-to-digital converter coupled to the electrocardiograph to receive the first measured biological function, coupled to the pressure detector to receive the second measured biological function, and further coupled to the probe to receive a probe measurement of a known probe displacement, wherein the processor includes instructions to determine a calibrated control voltage from the probe measurement, and to determine a first plurality of filter coefficients from the calibrated control voltage and from the first measured biological function, and to generate a first intermediate control voltage from the first measured biological function and from the first plurality of filter coefficients, wherein the processor includes further instructions to determine a second plurality of filter coefficients from He calibrated control voltage and from the second measured biological function, and to generate a second intermediate control voltage from the second measured biological function and from the second plurality of filter coefficients; and

wherein the processor includes further instructions to generate the control voltage as a linear superposition of the first intermediate control voltage and the second intermediate control voltage.

34. The system claim 33, wherein the probe measurement includes an impedance measurement of the probe during a known oscillatory movement having a known amplitude and frequency.

35. The system of claim 33, wherein the processor includes further instructions to determine the first and second pluralities of filter coefficients as inverse Fourier transforms of corresponding first and second pluralities of coefficients A(ω

), wherein the first and second pluralities of coefficients A(ω

) are determined in a frequency domain from a transfer function;

36. The system of claim 35, wherein the processor includes further instructions to determine, respectively, the first and second intermediate control voltages V_CONTROL(t) as: