Compensation reduction in tissue stimulation therapy

1. A method of treating a patient, comprising:

delivering an electrical signal to a nerve according to a first setting of an on-time and off-time that defines a duty cycle, wherein said on-time defines the time during which an electrical burst of pluses occurs and said off-time defines the time with no electrical burst of pulses; and

automatically changing said first setting to a second setting of on-time and off-time in response to a physiological event, wherein said second setting defines a duty cycle substantially equal to the duty cycle defined by said first setting;

wherein said second setting is different from said first setting.

2. The method of claim 1 , wherein changing said first setting to the second setting further comprises sensing an occurrence of said physiological event followed by changing said first setting to said second setting and repeating said sensing and changing.

3. The method of claim 1 wherein said physiological event comprises a change in a physiological parameter exceeding a defined threshold.

4. The method of claim 1 , further comprising changing said first setting to the second setting upon detecting a sensed user input.

5. The method of claim 1 , further comprising automatically changing said second setting to a third setting of on-time and off-time in response to a second event, wherein said third setting defines a duty cycle substantially equal to the duty cycle defined by said first and second settings.

6. A system, comprising:

at least one electrode coupled to a nerve;

a pulse generator coupled to said at least one electrode, wherein said pulse generator provides an electrical signal to a nerve using said at least one electrode; and a controller coupled to said pulse generator, wherein said controller causes said pulse generator to deliver said electrical signal to a nerve according to a first setting of an on-time and off-time that defines a first duty cycle and, in response to a physiological event, causes a change from said first setting to a second setting of an on-time and off- time that defines a second duty cycle that is no more than 5% different from the first duty cycle;

wherein said on-time defines the time during which an electrical burst of pulses occurs and said off-time defines the time with no electrical burst of pulses;

wherein said second setting is different from said first setting.

7. The system of claim 6 , further comprising a user input sensor coupled to the controller, wherein said user input sensor senses a manual control input to control an operation of the pulse generator.

8. The system of claim 7 , wherein said physiological event comprises a user activation parameter of said sensor in excess of an activation parameter threshold.

9. The system of claim 6 , further comprising a physiological sensor coupled to the controller to control, at least in part, changing from the first setting to the second setting.

10. The system of claim 6 wherein said physiological event comprises a change in a physiological parameter exceeding a threshold.

11. The system of claim 10 further comprising a user input sensor capable of sensing a user input signal, and wherein said controller causes the change from said first setting to the second setting upon detection of the physiological event and upon at least one of an expiration of a defined time period and a sensed user input signal.

12. A method of treating a patient having a medical condition, comprising:

applying to a vagus nerve of the patient a first electrical signal defined by a first plurality of parameters comprising a first on-time and a first off-time defining a first duty cycle;

determining the occurrence of a physiological event and, in response to said physiological event

ceasing said step of applying said first electrical signal to said vagus nerve, and

applying to said vagus nerve a second electrical signal defined by a second plurality of parameters comprising a second on-time and a second off-time defining a second duty cycle that differs from said first duty cycle by no more than 10%;

wherein each of said first and second on=times defines a time during which an electrical burst of pulses occurs and each of said first and second off-times define a time with no electrical burst of pulses;

wherein said second electrical signal is different from said first electrical signal.

13. The method of claim 12 wherein said first plurality of parameters comprises at least one of a first current magnitude, a first frequency, and a first pulse width, and said second plurality of parameters comprises at least one of a second current magnitude, a second frequency, and a second pulse width.

14. The method of claim 13 wherein at least one of said second current magnitude, said second frequency, and said second pulse width is the same as a respective one of said first current magnitude, said first frequency, and said first pulse width.

15. The method of claim 12 wherein applying said second electrical signal is also in response to at least one of a defined time period or a sensed user input, in addition to physiological event.

16. The method of claim 12 further comprising:

detecting the occurrence of a second event, and in response to said second event

ceasing said step of applying said second electrical signal to said vagus nerve, and

applying said first electrical signal to said vagus nerve.

17. The method of claim 12 further comprising:

detecting the occurrence of a second event, and in response to said second event

ceasing said step of applying said second electrical signal to said vagus nerve, and

applying to said vagus nerve a third electrical signal defined by a third plurality of parameters comprising a third on-time and a third off-time characterized by a third duty cycle substantially the same as said first duty cycle.

18. The method of claim 12 , wherein said second duty cycle differs from said first duty cycle by no more than 5%.