Battery monitoring apparatus and method for programmers of cardiac stimulating devices

• US 6,108,579 A
• Filed: 04/11/1997
• Issued: 08/22/2000
• Est. Priority Date: 04/15/1996
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Snell, Jeffrey D., Fox, J. Kelly
• Primary Examiner(s): CHANEY, CAROL DIANE
• Application Number:
  US08/832,717
• Time in Patent Office: 1,229 Days
• Field of Search: 429/90, 429/92, 607/29, 607/27
• US Class Current: 607/29
• CPC Class Codes: A61N 1/3708 for power depletion
• CPC Class Codes: A61N 1/372 Arrangements in connection with the implantation of stimulators
• CPC Class Codes: G01R 31/3646 for indicating electrical conditions or variables, e.g. visual or audible indicators
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A system and method for predicting and displaying a realistic time remaining to a recommended replacement time (RRT) of a battery of a implantable cardiac stimulating device or similar battery powered medical device is provided.

Claims

1. A system for providing a time remaining to a recommended battery replacement time of an implantable stimulation device, the system comprising:

pulse generating means for generating stimulation pulses to a patient'"'"'s body tissue in accordance with the patient'"'"'s needs;

e

a battery for powering the pulse generating means;

monitoring means, coupled to the pulse generating means and the battery, for monitoring a plurality of operating and battery parameters;

simulation means for simulation the operation of the pulse generating means based upon at least one operating characteristic of the device and at least one parameter representative of the state of the battery;

predicting means for forecasting a time remaining to the recommended replacement time of the battery based upon the simulation of the operation of the pulse generating means; and

display means for displaying the time remaining to the recommended replacement time of the battery.

2. The system of claim 1, wherein the monitoring means comprises:

means for monitoring at least battery voltage, current drain on the battery, and internal battery impedance; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on previous current drain usage.

3. The system of claim 1, wherein the monitoring means comprises:

means for monitoring a rate of stimulation pulses; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on a previous rate of the stimulation pulses.

4. The system of claim 1, wherein the monitoring means comprises:

means for monitoring at least one amplitude or pulse width of the stimulation pulses; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on the at least one of a previous amplitude or pulse width of the stimulation pulses.

5. The system of claim 4, further comprising:

means for varying at least one of the amplitude or the pulse width of the stimulation pulses in accordance with the patient'"'"'s threshold; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on at least one of the varying amplitude or pulse width of the stimulation pulses.

6. The system of claim 4, further comprising:

means for varying one of the amplitude or the pulse width of the stimulation pulses in accordance with the patient'"'"'s threshold; and

wherein the monitoring means comprises means for monitoring one of the average amplitude or average pulse width of the stimulation pulses; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on the one of the varying amplitude or pulse width of the stimulation pulses.

7. The system of claim 1, further comprising:

means for varying the rate of stimulation pulses based on physiological need;

wherein the monitoring means comprises means for monitoring the average rate of the stimulation pulses; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on the average rate of the stimulation pulses.

8. The system of claim 1, wherein the monitoring means comprises:

means for monitoring a percentage of paced events; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on the percentage of paced events.

9. The system of claim 1, further comprising:

means for lowering the rate during sleep;

wherein the monitoring means comprises means for monitoring an average rate of stimulation pulses over at least approximately one day; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on the average rate of stimulation pulses over at least the previous one day.

10. The system of claim 1, wherein:

the pulse generating means includes means for generating stimulation pulses in both a patient'"'"'s atrium and ventricle in the absence of P-waves and R-waves, respectively, and further includes means for inhibiting the generation of an atrial and ventricular stimulation pulses in the presence of P-waves and R-waves, respectively;

the monitoring means comprises means for monitoring a percentage of atrial and ventricular paced events; and

the predicting means includes means for forecasting the time remaining to the recommended replacement time based on the percentage of atrial and ventricular paced events.

11. The system of claim 1, wherein the pulse generating means includes means for generating high amplitude shocking pulses, wherein the monitoring means comprises:

means for monitoring one of frequency of therapy shocks delivered, therapeutic shock amplitude, and therapeutic shock waveform; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on the selected one of frequency of therapy shocks delivered, therapeutic shock amplitude, and therapeutic shock waveform.

12. The system of claim 1, wherein the implantable stimulation device includes ohmic circuits and charge pump circuitry which have current drain characteristics which vary as a function of declining battery voltage, wherein the monitoring means comprises:

means for revising the simulated device operating parameters after each simulated time frame to include changes to such parameters as a result of the declining simulated battery voltage and charge depleted during each time frame; and

wherein the simulation means simulates the operation of the pulse generator means for a plurality of time frames based on the device operating parameter; and

wherein the predicting means includes means for forecasting the time remaining to the recommended replacement time based on the simulated operation and the declining battery voltage.

13. A method for determining a time remaining to a recommended replacement time of a battery of an implantable cardiac stimulating device, comprising the steps of:

monitoring device operating and battery parameters from the stimulating device;

determining a first amount of battery charge actually depleted as a function of the battery parameters, the battery parameters including battery voltage, battery current drain, and internal battery impedance;

determining a second amount of battery charge corresponding to a point in time at which the stimulating device is recommended for replacement;

determining an amount of battery charge remaining to the recommended battery replacement time by subtracting the second amount of battery charge from the first amount of battery charge; and

predicting the time remaining to the recommended battery replacement time based on the amount of battery charge remaining and the monitored device operating parameters.

14. The method of claim 13, wherein the step of predicting the time remaining to the recommended battery replacement time further comprises the steps of:

simulating the operation of the stimulating device for a plurality of time frames based on the device operating parameters; and

revising the device operating parameters after each simulated time frame to include changes to such parameters as a result of the additional battery charge depleted during each time frame.

15. The method of claim 14, wherein the step of simulating the operation of the stimulation device comprises the steps of:

determining for each time frame the battery current drain as a function of the device operating parameters;

determining the battery charge depleted in each time frame based on the battery current drain determined for that time frame;

adding the battery charge depleted in each time frame to the first battery charge to get a predicted total charge needed for each additional time frame;

determining a battery impedance and from that determining a battery voltage;

comparing battery voltage with a target battery voltage associated with RRT;

repeating the foregoing steps until the calculated battery voltage is less than or equal to the target voltage;

determining the total simulated time of all time frames; and

displaying the total simulated time frame as the time remaining to the recommended battery replacement time.

16. The method of claim 13, wherein the device operating parameters include parameters selected from the group consisting of programmed rate of therapy delivery, programmed therapeutic shock amplitude, therapeutic shock waveform, and the ohmic resistance of the implantable cardiac stimulating device.

17. The method of claim 13, wherein determining the first battery charge depleted comprises retrieving from the implantable cardiac device a cumulative record of battery charge depleted.

18. A system for predicting a time remaining to a recommended replacement time of a battery of an implantable medical device, the system comprising:

means for inputting a request that a prediction be made of the time remaining to the recommended replacement time of the battery;

means, responsive to receipt of the request, for predicting the time remaining to the recommended replacement time of the battery, wherein the means for predicting comprises;

means for determining at least one operating characteristic of the device and at least one parameter representative of the state of the battery;

means for estimating a time remaining to the recommended replacement time of the battery based on the at least one operating characteristic of the device and the at least one parameter representative of the state of the battery, wherein the implantable medical device includes a pulse stimulation unit for providing stimulation pulses, and wherein the at least one operating characteristic of the pulse generating unit comprises a percentage of paced events, wherein the percentage of paced events includes one or more of a percentage of atrial paced events and a percentage of ventricular paced events; and

means for outputting a signal representative of the predicted time remaining to the recommended replacement time of the battery.

19. The system of claim 18, wherein the system is part of an external programmer device.

20. The system of claim 19, wherein the means for predicting the time remaining to the recommended replacement time of the battery includes means for interrogating the implantable medical device to determine at least one parameter representative of the state of the battery for use in making the prediction.

21. The system of claim 18, wherein the implantable medical device is capable of varying the rate, amplitude or pulse width of the stimulation pulses and wherein the at least one operating characteristic of the pulse generating unit is selected from a group consisting of:

a time-varying rate of the stimulation pulses, a time-varying amplitude of the stimulation pulses, and a time-varying pulse width of the stimulation pulses.

22. The system of claim 18, wherein the implantable medical device is capable of varying the rate, amplitude or pulse width of the stimulation pulses and wherein the at least one operating characteristic of the pulse generating unit is selected from a group consisting of:

an average rate of the stimulation pulses, an average amplitude of the stimulation pulses, and an average pulse width of the stimulation pulses.

23. The system of claim 22, wherein the averages and determined over at least one day.

24. The system of claim 23, wherein the averages are determined over approximately one previous day.

25. The system of claim 18, wherein the implantable medical device is capable of generating high amplitude shocking pulses and wherein the at least one operating characteristic of the pulse generating unit is selected from a group consisting of:

a frequency of therapy shocks delivered, a therapeutic shock amplitude, and a therapeutic shock waveform.

26. The system of claim 18, wherein means for predicting a time remaining to the recommended replacement time of the battery includes means for simulating the operation of the implantable medical device based upon the at least one operating characteristic of the device and the at least one parameter representative of the state of the battery.

27. The system of claim 26, wherein the at least one parameter representative of the state of the battery permits a determination of the amount of charge in the battery and wherein means for simulating the operation of the implantable medical device includes:

means for determining a current amount of charge in the battery based upon the at least one parameter representative of the state of the battery;

means for defining a plurality of time frames;

means for determining for each time frame an amount of charge expected to be depleted from the battery based on the at least one operating characteristic of the device; and

means for determining how many time frames elapse before the battery falls below a predetermined minimum acceptable amount of charge.

28. The system of claim 27, wherein the stimulation device includes ohmic circuits and charge pump circuitry which have current drain characteristics which vary as a function of declining battery voltage and wherein the means for determining for each time frame an amount of charge expected to be depleted from the battery operates by revising simulated device operating parameters after each time frame to include changes to the simulated device operating parameters as a result of a declining simulated battery voltage and any charge depleted during each time frame.

29. The system of claim 18, wherein the at least one parameter representative of the state of the battery is selected from a group consisting of:

battery voltage, current drain on the battery, and internal battery impedance.

30. A method for predicting a time remaining to a recommended replacement time of a battery of an implantable medical device, the method comprising the steps of:

inputting a request that a prediction be made of the time remaining to the recommended replacement time of the battery;

predicting, in response to receipt of the request, the time remaining to the recommended replacement time of the battery, wherein the step of predicting comprises;

determining at least one operating characteristic of the device and at least one parameter representative of the state of the battery; and

simulating the operation of the implantable medical device based upon the at least one operating characteristic of the device and the at least one parameter representative of the state of the battery;

estimating a time remaining to the recommended replacement time of the battery based on the at least one operating characteristic of the device and the at least one parameter representative of the state of the battery; and

outputting a signal representative of the predicted time remaining to the recommended replacement time of the battery.

31. The method of claim 30 performed by an external programmer device.

32. The method of claim 31, wherein the step of predicting the time remaining to the recommended replacement time of the battery includes the step of interrogating the implantable medical device to determine at least one parameter representative of the state of the battery for use in making the prediction.

33. The method of claim 30, wherein the at least one parameter representative of the state of the battery permits a determination of the amount of charge in the battery and wherein the step of simulating the operation of the implantable medical device includes the steps of:

determining a current amount of charge in the battery based upon the at least one parameter representative of the state of the battery;

defining a plurality of time frames;

determining for each time frame an amount of charge expected to be depleted from the battery based on the upon the at least one operating characteristic of the device; and

determining how many time frames elapse before the battery falls below a predetermined minimum acceptable amount of charge.

34. The method of claim 33, wherein the implantable medical device includes ohmic circuits and charge pump circuitry which have current drain characteristics which vary as a function of declining battery voltage and wherein the step of determining for each time frame an amount of charge expected to be depleted from the battery operates by revising simulated device operating parameters after each time frame to include changes to the simulated device operating parameters as a result of a declining simulated battery voltage and any charge depleted during each time frame.

35. A system for predicting a time remaining to a recommended replacement time of a battery of an implantable medical device, the system comprising:

an input unit for inputting a request that a prediction be made of the time remaining to the recommended replacement time of the battery;

a prediction unit, operative in response to receipt of the request, for predicting the time remaining to the recommended replacement time of the battery, wherein the a prediction unit comprises;

a determination unit for determining at least one operating characteristics of the device and at least one parameter representative of the state of the battery; and

a simulation unit for simulating the operation of the implantable medical device based upon the at least one operating characteristic of the device and the at least one parameter representative of the state of the battery;

an estimation unit for estimating a time remaining to the recommended replacement time of the battery based upon the simulation of the operation of the implantable medical device; and

an output unit for outputting a signal representative of the predicted time remaining to the recommended replacement time of the battery.

36. The system of claim 35, wherein the system is part of an external programmer device.

37. The system of claim 36, wherein the prediction unit includes an interrogation unit for interrogating the implantable medical device to determine at least one parameter representative of the state of the battery for use in making the prediction.

38. The system of claim 35, wherein the at least one parameter representative of the state of the battery permits a determination of the amount of charge in the battery and wherein the simulation unit includes:

a charge determination unit for determining a current amount of charge in the battery based upon the at least one parameter representative of the state of the battery;

a time frame unit for defining a plurality of time frames;

a depletion determination unit for determining for each time frame an amount of charge expected to be depleted from the battery based on the upon the at least one operating characteristic of the device; and

a threshold determination unit for determining how many time frames elapse before the battery falls below a predetermined minimum acceptable amount of charge.

39. The system of claim 38, wherein the implantable medical device includes ohmic circuits and charge pump circuitry which have current drain characteristics which vary as a function of declining battery voltage and wherein the depletion determination unit operates by revising simulated device operating parameters after each time frame to include changes to the simulated device operating parameters as a result of a declining simulated battery voltage and any charge depleted during each time frame.