Safety control system for implantable neural stimulator

• US 20060271108A1
• Filed: 05/24/2005
• Published: 11/30/2006
• Est. Priority Date: 05/24/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Stahmann, Jeffrey E., Kramer, Andrew P., Libbus, Imad, Linder, William J.
• Granted Patent: US 7,551,958 B2
• Time in Patent Office: Days
• US Class Current: 607/2
• CPC Class Codes: A61N 1/36114 Cardiac control, e.g. by vagal stimulation stimulating the heart A61N1/362
• CPC Class Codes: A61N 1/36139 with automatic adjustment
• CPC Class Codes: A61N 1/36142 for improving safety
• CPC Class Codes: A61N 1/37 Monitoring; Protecting

Abstract

A neural stimulation system includes a safety control system that prevents delivery of neural stimulation pulses from causing potentially harmful effects. The neural stimulation pulses are delivered to one or more nerves to control the physiological functions regulated by the one or more nerves. Examples of such harmful effects include unintended effects in physiological functions associated with autonomic neural stimulation and nerve injuries caused by excessive delivery of the neural stimulation pulses.

Claims

1. A neural stimulation system, comprising:

a stimulation output circuit including at least one stimulation channel to deliver neural stimulation pulses;

a stimulation controller, coupled to the stimulation output circuit, to control the delivery of the neural stimulation pulses using a plurality of stimulation parameters; and

a safety controller coupled to the stimulation controller, the safety controller including;

a safety-control event detection module adapted to detect a safety-control event, the safety-control event detection module including at least one of an energy detection module adapted to detect a stimulation energy being an energy of one or more of the neural stimulation pulses and a stimulation parameter detection module adapted to detect one or more parameter values each being a value of a parameter of the plurality of stimulation parameters; and

a safety response module adapted to adjust one or more parameters of the plurality of stimulation parameters in response to the detection of the safety-control event.

2. The neural stimulation system of claim 1, wherein the safety response module comprises a parameter limiting module adapted to set a value of a parameter of the plurality of stimulation parameters to a threshold value of that parameter when the value of that parameter exceeds the threshold value of that parameter.

3. The neural stimulation system of claim 1, wherein the safety response module comprises a stimulation switching module to suspend the delivery of the neural stimulation pulses though the at least one stimulation channel when the safety-control event is detected.

4. The neural stimulation system of claim 1, wherein the energy detection module is adapted to detect the stimulation energy being an energy of one neural stimulation pulse of the neural stimulation pulses delivered through the at least one stimulation channel, and wherein the safety-control event detection module is adapted to indicate a detection of the safety-control event when the stimulation energy exceeds a predetermined threshold energy.

5. The neural stimulation system of claim 1, wherein the energy detection module is adapted to detect the stimulation energy being a total energy of the neural stimulation pulses delivered through the at least one stimulation channel over a predetermined period of time, and wherein the safety-control event detection module is adapted to indicate a detection of the safety-control event when the stimulation energy exceeds a predetermined threshold energy.

6. The neural stimulation system of claim 1, further comprising an implantable housing configured to contain a neural stimulation circuit including the stimulation output circuit, the stimulation controller, and the safety controller.

7. The neural stimulation system of claim 1, wherein the safety-control event detection module is adapted to indicate a detection of the safety-control event when at least a first parameter value being a value of a first parameter of the plurality of stimulation parameters exceeds a first threshold value of the first parameter.

8. The neural stimulation system of claim 7, wherein the safety-control event detection module further comprises a threshold adjustment module adapted to dynamically adjust the first threshold value based on at least a second parameter value of a second parameter of the plurality of stimulation parameters.

9. The neural stimulation system of claim 7, wherein the safety-control event detection module further comprises a look-up table relating the first threshold value to at least a second parameter value of a second parameter of the plurality of stimulation parameters.

10. The neural stimulation system of claim 7, wherein the stimulation controller is adapted to control a delivery of bursts of pulses of the neural stimulation pulses using stimulation parameters selected from:

a pulse amplitude being an amplitude of a pulse of the neural stimulation pulses;

a pulse width being a width of a pulse of the neural stimulation pulses;

a stimulation frequency being a frequency at which the neural stimulation pulses are delivered during the delivery of a burst of the bursts of pulses;

a burst duration during which a burst of the bursts of pulses is delivered;

a burst interval at which the bursts of the neural stimulation pulses are delivered; and

a stimulation duty cycle being a ratio of the burst duration to the burst interval.

11. The neural stimulation system of claim 1, wherein the safety-control event detection module comprises the energy detection module and the stimulation parameter detection module and is adapted to indicate a detection of the safety-control event when the stimulation energy exceeds a predetermined threshold energy and when at least a first parameter value being a value of a first parameter of the plurality of stimulation parameters exceeds a first threshold value of the first parameter.

12. The neural stimulation system of claim 1, wherein the safety-control event detection module further comprises an unintended effect detection module to detect unintended effects associated with the delivery of the neural stimulation pulses.

13. The neural stimulation system of claim 12, wherein the unintended effect detection module comprises a physiological parameter detection module adapted to sense a value of the physiological parameter, compare the sensed value to a normal value range including one or more threshold values, and indicating a detection of the unintended effect when the sensed value falls out of the normal value range.

14. The neural stimulation system of claim 12, wherein the unintended effect detector is adapted to receive a signal indicative of the detection of the unintended effect.

15. The neural stimulation system of claim 12, wherein the unintended effect detector is adapted to sense a signal indicative of the unintended effect and detect the unintended effect from that signal.

16. The neural stimulation system of claim 15, wherein the unintended effect detector comprises an unintended cardiac event detector to detect an unintended cardiac event.

17. The neural stimulation system of claim 16, wherein the unintended effect detector further comprises an unintended pulmonary event detector to detect an unintended pulmonary event.

18. A method for neural stimulation, comprising:

delivering neural stimulation pulses through at least one electrode;

controlling the delivery of the neural stimulation pulses using a plurality of stimulation parameters;

detecting a safety-control event, including detecting at least one of a stimulation energy being an energy of one or more neural stimulation pulses of the neural stimulation pulses delivered through the at least one electrode and one or more parameter values each being a value of a parameter of the plurality of stimulation parameters; and

adjusting one or more parameters of the plurality of stimulation parameters in response to the detection of the safety-control event.

19. The method of claim 18, wherein adjusting the one or more parameters in response to the detection of the safety-control event comprises setting a value of a parameter of the plurality of stimulation parameters to a threshold value of that parameter when the value of that parameter exceeds the threshold value of that parameter.

20. The method of claim 18, wherein adjusting the one or more parameters in response to the detection of the safety-control event comprises adjusting the plurality of stimulation parameters to suspend the delivery of the neural stimulation pulses through the at least one stimulation channel when the safety-control event is detected.

21. The method of claim 18, wherein adjusting the one or more parameters in response to the detection of the safety-control event comprises adjusting the plurality of stimulation parameters to reduce an intensity of the delivery of the neural stimulation pulses through the at least one stimulation channel when the safety-control event is detected.

22. The method of claim 18, wherein controlling the delivery of the neural stimulation pulses comprises controlling a delivery of bursts of pulses of the neural stimulation pulses using stimulation parameters selected from:

a pulse amplitude being an amplitude of a pulse of the neural stimulation pulses;

a pulse width being a width of a pulse of the neural stimulation pulses;

a stimulation frequency being a frequency at which the neural stimulation pulses are delivered during the delivery of a burst of the bursts of pulses;

a burst duration during which one burst of the bursts of pulses is delivered;

a burst interval at which the bursts of the neural stimulation pulses are delivered; and

;

a stimulation duty cycle being a ratio of the burst duration to the burst interval.

23. The method of claim 22, wherein detecting the safety-control event comprises indicating a detection of the safety-control event when at least a first parameter value being a value of a first parameter of the plurality of stimulation parameters exceeds a first threshold value of the first parameter.

24. The method of claim 23, further comprising dynamically adjusting the first threshold based on at least a second parameter value of a second parameter of the plurality of stimulation parameters.

25. The method of claim 24, wherein detecting the safety-control event comprises determining the first threshold using a look-up table relating the first threshold to at least a second parameter value of a second parameter of the plurality of stimulation parameters.

26. The method of claim 18, wherein detecting the safety-control event further comprises detecting one or more unintended effects associated with the delivery of the neural stimulation pulses.

27. The method of claim 26, wherein detecting the safety-control event comprises indicating a detection of the safety-control event when the stimulation energy exceeds a predetermined threshold energy and when one of the unintended effects is detected.

28. The method of claim 26, wherein detecting the safety-control event comprises indicating a detection of the safety-control event when at least a first parameter value being a value of a first parameter of the plurality of stimulation parameters exceeds a first threshold value of the first parameter and when one of the unintended effects is detected.

29. The method of claim 26, wherein detecting one or more unintended effects comprises sensing a value of the physiological parameter, comparing the sensed value to a normal value range including one or more threshold values, and indicating a detection of the unintended effect when the sensed value falls out of the normal value range.

30. The method of claim 26, wherein detecting one or more unintended effects comprises receiving a signal indicative of the detection of the unintended effect.

31. The method of claim 26, wherein detecting one or more unintended effects comprises sensing a signal indicative of the unintended effect and detecting the unintended effect from that signal.

32. The method of claim 31, wherein detecting one or more unintended effects comprises detecting one or more of bradycardia, atrial flutter, atrial fibrillation, ventricular tachycardia, ventricular fibrillation, asystole, and hypotension.

33. The method of claim 31, wherein detecting one or more unintended effects comprises detecting one or more of dyspnea, coughing, apnea, and hypopena.