ECG electrode characterization and compensation

• US 20060015033A1
• Filed: 07/19/2004
• Published: 01/19/2006
• Est. Priority Date: 07/19/2004
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Simske, Steven J., Zhang, Tong, Blakley, Daniel R.
• Granted Patent: US 7,245,961 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/30 Input circuits therefor

Abstract

Systems, methodologies, media, and other embodiments associated with electrocardiogram electrode characterization and compensation are described. One exemplary system embodiment includes a characterization logic configured to generate signals designed to facilitate characterizing an electrocardiogram electrode. The characterization logic may also be configured to analyze signals produced in response to introducing the signals into a subject. The example system may also include a compensation logic configured to determine whether an electrode is performing in a desired manner and to selectively compensate for electrode performance.

Claims

1. A system, comprising:

a characterization logic configured to characterize a signal transferring property of a first electrode associated with an electrocardiogram (ECG) apparatus, the first electrode being configured to receive electrocardiac signals from a subject to be monitored by the electrocardiogram apparatus; and

a compensation logic operably connected to the characterization logic, the compensation logic being configured to manipulate electrocardiac signals received by the first electrode based, at least in part, on the characterization of the signal transferring property.

2. The system of claim 1, the characterization logic being configured to provide a set of characterizing signals to a second electrode configured to transmit the set of characterizing signals into the subject, the characterization logic being configured to receive through the first electrode a set of property revealing signals produced in response to the set of characterizing signals being transmitted into the subject.

3. The system of claim 2, the subject being one of, a human body, an equine body, a bovine body, a canine body, and a feline body.

4. The system of claim 2, the characterization logic being configured to configure an impedance transfer function logic with an impedance transfer function that characterizes a skin/electrode impedance associated with the first electrode.

5. The system of claim 4, the impedance transfer function logic being configured with data values representing a mathematical approximation of the impedance transfer function that characterizes the skin/electrode impedance associated with the first electrode.

6. The system of claim 5, the compensation logic being configured to dynamically manipulate the electrocardiac signal by selectively providing the electrocardiac signal to a logic configured to selectively reconfigure the impedance transfer logic to add one or more of, a pole, and a zero to the impedance transfer function by manipulating a data value representing an additional term to the mathematical approximation of the impedance transfer function based, at least in part, on one or more of, an amplitude response of the impedance transfer function over a range of frequencies, and a frequency response of the impedance transfer function over a range of frequencies.

7. The system of claim 4, the impedance transfer function logic comprising a field programmable gate array (FPGA) configured to simulate the impedance transfer function.

8. The system of claim 7, the compensation logic being configured to dynamically manipulate the electrocardiac signal by selectively providing the electrocardiac signal to a logic configured to selectively reconfigure the impedance transfer logic to add one or more of, a pole, and a zero to the impedance transfer function by reconfiguring the field programmable gate array based, at least in part, on one or more of, an amplitude response of the impedance transfer function over a range of frequencies, and a frequency response of the impedance transfer function over a range of frequencies.

9. The system of claim 4, the set of characterizing signals including signals having an amplitude configured within a configurable range of amplitudes and a frequency configured within a configurable range of frequencies.

10. The system of claim 9, the configurable range of amplitudes comprising 1 mV to 25 mV.

11. The system of claim 10, the configurable range of frequencies comprising 0.05 Hz to 128 Hz.

12. The system of claim 4, the set of characterizing signals including a sine-squared pulse formed from a set of signals having configurable frequencies within a range of 0.05 Hz to 128 Hz.

13. The system of claim 4, the characterization logic being configured to provide the set of characterizing signals to the second electrode at times including, before an electrocardiac signal of interest is received by the first electrode, substantially in parallel with receiving and processing electrocardiac signals of interest, and substantially in parallel with receiving and selectively ignoring electrocardiac signals of interest.

14. The system of claim 13, the characterization logic being configured to characterize the signal transferring property of the first electrode at times including before an electrocardiac signal of interest is received by the first electrode, substantially in parallel with receiving and processing electrocardiac signals of interest, and substantially in parallel with receiving and selectively ignoring electrocardiac signals of interest.

15. The system of claim 4, including a set of AC-coupled amplifiers operably connected to the first electrode and one or more third electrodes associated with the electrocardiogram apparatus, the one or more third electrodes being configured to receive electrocardiac signals from a heart to be monitored by the electrocardiogram apparatus, the set of AC-coupled amplifiers being configured to receive and manipulate the electrocardiac signals.

16. The system of claim 4, including a set of DC-coupled amplifiers operably connected to the first electrode and one or more third electrodes associated with the electrocardiogram apparatus, the one or more third electrodes being configured to receive electrocardiac signals from a heart to be monitored by the electrocardiogram apparatus, the set of DC-coupled amplifiers being configured to receive and manipulate the electrocardiac signals, the set of DC-coupled amplifiers being operably connected to a simulation logic configured to simulate AC-coupling between the set of DC-coupled amplifiers by applying a high pass filter operation to the electrocardiac signal.

17. The system of claim 4, the characterization logic being configured to analyze one or more of, an amplitude response of the impedance transfer function over a range of frequencies associated with the set of characterizing signals, and a phase response of the impedance transfer function over the range of frequencies.

18. The system of claim 4, the compensation logic being configured to statically manipulate the electrocardiac signal by one or more of, selectively providing the electrocardiac signal to a circuit component configured to manipulate the amplitude of the electrocardiac signal based, at least in part, on an amplitude response of the impedance transfer function, and selectively providing the electrocardiac signal to a circuit component configured to manipulate the phase of the electrocardiac signal based, at least in part, on a phase response of the impedance transfer function.

19. The system of claim 4, the compensation logic being configured to dynamically manipulate the electrocardiac signal by one or more of, selectively providing the electrocardiac signal to a circuit component configured to manipulate the amplitude of the electrocardiac signal based, at least in part, on an amplitude response of the impedance transfer function, and selectively providing the electrocardiac signal to a circuit component configured to manipulate the phase of the electrocardiac signal based, at least in part, on a phase response of the impedance transfer function.

20. The system of claim 4, the compensation logic being configured to dynamically manipulate the electrocardiac signal by selectively providing the electrocardiac signal to a logic configured to selectively reconfigure the impedance transfer logic to add one or more of, a pole, and a zero to the impedance transfer function based, at least in part, on one or more of, an amplitude response of the impedance transfer function over a range of frequencies, and a frequency response of the impedance transfer function over a range of frequencies.

21. The system of claim 4, the compensation logic being configured to dynamically manipulate the electrocardiac signal by manipulating one or more of, the phase of the electrocardiac signal, and the amplitude of the electrocardiac signal by an amount determined, at least in part, by an inverse corrective data derived from a transformed input data acquired during the characterizing of the signal transferring property.

22. The system of claim 21, the transformed input data comprising one or more of, a Fourier transformed input data, a wavelet transformed input data, and a Hilbert transformed input data.

23. The system of claim 4, the compensation logic being configured to dynamically manipulate the electrocardiac signal by applying a set of impulse response filter coefficients to the electrocardiac signal to produce an inverse complex correction factor for one or more of, amplitude with respect to frequency, and phase with respect to frequency.

24. The system of claim 23, the impulse filter coefficients comprising one or more of, finite impulse response filter coefficients, and infinite impulse response filter coefficients.

25. The system of claim 1, the electrode being a dry electrode that may be attached to an unprepared skin surface.

26. A method, comprising:

analyzing a performance characteristic of an electrode associated with an electrocardiogram apparatus, the electrode being configured to receive an electrocardiac signal from a heart of a subject to be monitored by the electrocardiogram apparatus;

selectively manipulating the electrocardiac signal received at the electrode based on analyzing the performance characteristic of the electrode; and

providing the electrocardiac signal to the electrocardiogram apparatus.

27. The method of claim 26, where analyzing the performance characteristic of the electrode comprises:

providing a set of outbound signals to a second electrode configured to transmit the set of outbound signals into the subject, where members of the set of outbound signals vary in one or more of, amplitude, and frequency; and

receiving a set of inbound signals produced in response to the set of outbound signals transiting the body.

28. The method of claim 27, where the set of outbound signals facilitates analyzing an electrode/skin impedance associated with the electrode as applied to the subject.

29. The method of claim 28, where analyzing the electrode/skin impedance comprises:

producing an impedance transfer function that describes a signal processing characteristic of the electrode; and

analyzing a phase response and magnitude response of the impedance transfer function over a range of frequencies.

30. The method of claim 27, where selectively manipulating an electrocardiac signal received at the electrode includes one or more of, amplifying, attenuating, and phase shifting the electrocardiac signal based, at least in part, on a relationship between an observed performance of the electrode and a desired performance for the electrode.

31. The method of claim 27, where one or more signals of the set of the outbound signals is provided and the inbound signal is received at times including one or more of, before an electrocardiac signal of interest is received by the electrode, substantially in parallel with receiving and processing an electrocardiac signal of interest, and substantially in parallel with receiving and selectively ignoring an electrocardiac signal.

32. The method of claim 31, where the performance characteristic of the electrode is analyzed at times including one or more of, before an electrocardiac signal of interest is received by the electrode, substantially in parallel with receiving and processing an electrocardiac signal of interest, and substantially in parallel with receiving and selectively ignoring an electrocardiac signal.

33. The method of claim 28, where selectively manipulating the electrocardiac signal includes statically manipulating the electrocardiac signal to compensate for the electrode/skin impedance, the manipulating comprising one or more of, selectively manipulating the amplitude of the electrocardiac signal, and selectively manipulating the phase of the electrocardiac signal.

34. The method of claim 28, where selectively manipulating an electrocardiac signal includes dynamically manipulating the electrocardiac signal to compensate for the electrode/skin impedance, the manipulating comprising one or more of, selectively manipulating the amplitude of the electrocardiac signal, and selectively manipulating the phase of the electrocardiac signal.

35. The method of claim 34, where dynamically manipulating the electrocardiac signal includes one or more of, manipulating the amplitude of the electrocardiac signal by an amount determined, at least in part, by a first inverse corrective data derived from a transformed input data acquired during the analyzing of the performance characteristic of the electrode, and manipulating the phase of the electrocardiac signal by an amount determined, at least in part, by a second inverse corrective data derived from the transformed input data acquired during the analyzing of the performance characteristic of the electrode.

36. The method of claim 35, the transformed input data having been transformed by one or more of, a Fourier transform, a wavelet transform, and a Hilbert transform.

37. The method of claim 34, where dynamically manipulating the electrocardiac signal includes applying a set of impulse response filter coefficients to the electrocardiac signal to effect an inverse complex correction for one or more of, amplitude with respect to frequency, and phase with respect to frequency.

38. The method of claim 37, the impulse response filter coefficients comprising one or more of, finite impulse response filter coefficients, and infinite impulse response filter coefficients.

39. A method, comprising:

analyzing a performance characteristic of an electrode associated with an electrocardiogram apparatus, the electrode being configured to receive an electrocardiac signal from a heart of a subject to be monitored by the electrocardiogram apparatus, where analyzing the performance characteristic includes;

providing a set of outbound signals that vary in one or more of, amplitude, and frequency to a second electrode configured to transmit the set of outbound signals into the subject, where the set of outbound signals facilitates analyzing an electrode/skin impedance associated with the electrode as applied to the subject, and where analyzing the electrode/skin impedance includes;

producing an impedance transfer function that describes a signal processing operation of the electrode; and

analyzing the phase response and magnitude response of the impedance transfer function over a range of frequencies; and

receiving a set of inbound signals produced in response to the set of outbound signals passing through the subject;

selectively manipulating the electrocardiac signal received at the electrode based on analyzing the performance characteristic of the electrode; and

providing the electrocardiac signal to the electrocardiogram apparatus.

40. A computer-readable medium storing processor executable instructions operable to perform a method, the method comprising:

analyzing a performance characteristic of an electrode associated with an electrocardiogram apparatus, the electrode being configured to receive an electrocardiac signal from a heart of a subject to be monitored by the electrocardiogram apparatus, where analyzing the performance characteristic includes;

providing a set of outbound signals that vary in one or more of, amplitude, phase, and frequency to a second electrode configured to transmit the set of outbound signals into the subject, where the set of outbound signals facilitates analyzing an electrode/skin impedance associated with the electrode as applied to the subject, and where analyzing the electrode/skin impedance includes;

producing an impedance transfer function that describes a signal processing operation of the electrode; and

analyzing the phase response and magnitude response of the impedance transfer function over a range of frequencies; and

receiving a set of inbound signals produced in response to the set of outbound signals passing through the subject;

selectively manipulating the electrocardiac signal received at the electrode based on analyzing the performance characteristic of the electrode; and

providing the electrocardiac signal to the electrocardiogram apparatus.

41. A system, comprising:

means for characterizing an impedance characteristic of one or more electrodes associated with an electrocardiogram apparatus, the one or more electrodes being a dry electrode applicable to an unprepared surface on a subject, the one or more electrodes being configured to detect an electrocardiac signal associated with a heart of the subject to be monitored by the electrocardiogram apparatus; and

means for selectively manipulating the electrocardiac signal received at the one or more electrodes based on the characterizing of the impedance characteristic of the one or more electrodes.

42. An electrocardiogram apparatus configured to monitor an electrocardiac signal, the electrocardiogram apparatus being configured with a skin/electrode impedance transfer function logic, the skin/electrode impedance transfer logic being configured to characterize an impedance characteristic of an electrode configured to detect and provide the electrocardiac signal to the electrocardiogram apparatus, the skin/electrode impedance transfer logic being configured to selectively manipulate the electrocardiac signal before providing the electrocardiac signal to the electrocardiogram apparatus, where the manipulating is based, at least in part, on the characterizing of the impedance characteristic of the electrode.

43. The electrocardiogram apparatus of claim 42, where the skin/electrode impedance transfer function logic is configured to selectively produce an alarm signal when the impedance characteristic of the electrodes meets an alarm criterion.

44. The electrocardiogram apparatus of claim 42, the electrocardiogram apparatus being configured to selectively deactivate when a pre-defined amount of ECG data has been received.

45. The electrocardiogram apparatus of claim 42, the electrocardiogram apparatus being configured to selectively deactivate when the impedance characteristic of the electrodes exceeds a performance tolerance.