METHOD AND APPARATUS FOR NEURAL STIMULATION WITH RESPIRATORY FEEDBACK

• US 20080058892A1
• Filed: 08/30/2006
• Published: 03/06/2008
• Est. Priority Date: 08/30/2006
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Kwok, Jonathan, Lee, Kent, Libbus, Imad, Caparso, Anthony V., James, Kristofer J., Haefner, Paul A., Pu, Yachuan
• Granted Patent: US 8,121,692 B2
• Time in Patent Office: Days
• US Class Current: 607/45
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61N 1/3601 of respiratory organs
• CPC Class Codes: A61N 1/36053 adapted for vagal stimulation A61N1/36114 takes precedence
• CPC Class Codes: A61N 1/36114 Cardiac control, e.g. by vagal stimulation stimulating the heart A61N1/362

Abstract

A neural stimulation system controls the delivery of neural stimulation using a respiratory signal as a therapy feedback input. The respiratory signal is used to increase the effectiveness of the neural stimulation, such as vagal nerve stimulation, while decreasing potentially adverse side effects in respiratory functions. In one embodiment, the neural stimulation system synchronizes the delivery of the neural stimulation pulses to the respiratory cycles using a respiratory fiducial point in the respiratory signal and a delay interval. In another embodiment, the neural stimulation system detects a respiratory disorder and, in response, adjusts the delivery of the neural stimulation pulses and/or delivers a respiratory therapy treating the detected respiratory disorder.

Claims

1. A neural stimulation system, comprising:

a stimulation output circuit adapted to deliver a neural stimulation therapy;

a stimulation delivery controller coupled to the stimulation output circuit, the stimulation delivery controller adapted to control the delivery of the neural stimulation therapy by executing one or more stimulation algorithms;

a respiratory signal input adapted to receive a respiratory signal indicative of respiratory cycles;

a respiratory disorder detector coupled to the respiratory signal input, the respiratory disorder detector adapted to detect a respiratory disorder using the respiratory signal; and

a stimulation switch coupled to the respiratory disorder detector and the stimulation delivery controller, the stimulation switch adapted to stop executing a first stimulation algorithm of the one or more stimulation algorithms in response to the detection of the respiratory disorder.

2. The system of claim 1, wherein the respiratory disorder detector is adapted to detect a respiratory disorder induced by the delivery of the neural stimulation therapy.

3. The system of claim 2, further comprising a physiologic sensor adapted to sense one or more physiologic signals, and wherein the respiratory disorder detector is adapted to detect the respiratory disorder using the respiratory signal and the one or more physiologic signals.

4. The system of claim 1, wherein the respiratory signal is indicative of a non-breathing period, and the respiratory disorder detector comprises an apnea detector adapted to detect apnea by comparing the non-breathing period to a detection threshold period.

5. The system of claim 1, wherein the respiratory signal is indicative of a tidal volume, and the respiratory disorder detector comprises a hypopnea detector adapted to detect hypopnea by comparing the tidal volume to a detection threshold volume.

6. The system of claim 1, wherein the respiratory signal is indicative of a respiratory rate and a tidal volume, and the respiratory disorder detector comprises a dyspnea detector adapted to detect dyspnea by comparing a ratio of the respiratory rate to the tidal volume to a detection threshold ratio.

7. The system of claim 1, wherein the stimulation switch is adapted to resume executing the first stimulation algorithm after a predetermined suspension period.

8. The system of claim 1, wherein the stimulation switch is adapted to resume executing the first stimulation algorithm when the respiratory disorder is no longer detected.

9. The system of claim 1, wherein the stimulation switch is adapted to stop executing the first stimulation algorithm and start executing a second stimulation algorithm in response to the detection of the respiratory disorder.

10. The system of claim 9, wherein the first stimulation algorithm comprises a stimulation algorithm adapted to treat a non-respiratory disorder, and the second stimulation algorithm is adapted to treat the respiratory disorder.

11. The system of claim 9, wherein the first stimulation algorithm comprises a stimulation algorithm adapted to treat a non-respiratory disorder, and the second stimulation algorithm is adapted to treat the non-respiratory disorder and the respiratory disorder.

12. The system of claim 1, further comprising a synchronization module coupled to the stimulation delivery controller and the respiratory signal input, the synchronization module adapted to synchronize the delivery of the neural stimulation therapy to the respiratory cycles.

13. The system of claim 12, wherein the synchronization module comprises:

a respiratory fiducial point detector to detect respiratory fiducial points from the respiratory signal; and

a delay timer adapted to time a delay interval starting with each of the detected respiratory fiducial points,

and wherein the stimulation delivery controller is adapted to cause the pulse output circuit to deliver a burst of neural stimulation pulses when the delay interval expires.

14. The system of claim 13, wherein the respiratory fiducial point detector comprises a peak detector adapted to detect peaks of the respiratory signal, and the delay timer is adapted to time a delay interval starting with each of the detected peaks of the respiratory signal.

15. A method for neural stimulation, the method comprising:

controlling a delivery of neural stimulation by executing one or more stimulation algorithms;

receiving a respiratory signal indicative of respiratory cycles;

detecting a respiratory disorder using the respiratory signal; and

stopping executing a first stimulation algorithm of the one or more stimulation algorithms in response to the detection of the respiratory disorder.

16. The method of claim 15, wherein detecting the respiratory disorder comprises detecting a respiratory disorder caused or worsened by the delivery of the neural stimulation.

17. The method of claim 15, wherein receiving the respiratory signal comprises receiving a non-breathing period, and detecting the respiratory disorder comprises detecting apnea by comparing the non-breathing period to a detection threshold period.

18. The method of claim 15, wherein receiving the respiratory signal comprises receiving a tidal volume, and detecting the respiratory disorder comprises detecting hypopnea by comparing the tidal volume to a detection threshold volume.

19. The method of claim 15, wherein receiving the respiratory signal comprises receiving a respiratory rate and a tidal volume, and detecting the respiratory disorder comprises detecting dyspnea by comparing a ratio of the respiratory rate to the tidal volume to a detection threshold ratio.

20. The method of claim 15, further comprising resuming executing the first stimulation algorithm after a predetermined suspension period.

21. The method of claim 15, further comprising resuming executing the first stimulation algorithm after a predetermined suspension period when the respiratory disorder is no longer detected.

22. The method of claim 15, further comprising starting executing a second stimulation algorithm in response to the detection of the respiratory disorder.

23. The method of claim 22, wherein starting executing the second stimulation algorithm comprises lowering a stimulation intensity associated with the neural stimulation.

24. The method of claim 22, wherein stopping executing the first stimulation algorithm comprises stopping delivering a neural stimulation therapy treating a cardiac disorder, and starting executing the second stimulation algorithm comprises starting a respiratory therapy treating the detected respiratory disorder.

25. The method of claim 24, wherein starting the respiratory therapy comprises starting one or more of a neural stimulation therapy treating the detected respiratory disorder, a cardiac pacing therapy, and an external pressure therapy.

26. The method of claim 15, further comprising

detecting predetermined-type respiratory fiducial points from the respiratory signal;

starting a delay interval with each of the detected predetermined-type respiratory fiducial points; and

delivering a burst of neural stimulation pulses when the delay interval expires.

27. A neural stimulation system, comprising:

a stimulation output circuit adapted to deliver neural stimulation pulses;

a respiratory signal input adapted to receive a respiratory signal indicative of respiratory cycles and respiratory parameters;

a synchronization module coupled to the stimulation output circuit and the respiratory signal input, the synchronization module including;

a peak detector coupled to the respiratory signal input, the peak detector adapted to detect peaks of the respiratory signal; and

a delay timer coupled to the peak detector, the delay timer adapted to time a delay interval starting with each of the detected peaks of the respiratory signal; and

a stimulation delivery controller coupled to the delay timer and the stimulation output circuit, the stimulation delivery controller adapted to cause the stimulation output circuit to deliver a burst of the neural stimulation pulses when the delay interval expires.

28. The system of claim 27, wherein the synchronization module comprises a delay generator adapted to adjust the delay interval using the respiratory signal.

29. The system of claim 28, wherein the delay generator is adapted to calculate the delay interval as a function of one or more of the respiratory parameters.

30. The system of claim 27, further comprising:

an implantable medical device including the stimulation output circuit, the respiratory signal input, the synchronization module, and the stimulation delivery controller;

an implantable respiratory sensor adapted to sense a physiologic signal; and

a sensor processing circuit adapted to produce the respiratory signal using the physiologic signal.

31. The system of claim 30, wherein the implantable respiratory sensor comprises an implantable impedance sensor adapted to sense a transthoracic impedance.

32. The system of claim 30, wherein the implantable respiratory sensor comprises an implantable pulmonary artery pressure (PAP) sensor.

33. A method for neural stimulation, the method comprising:

receiving a respiratory signal;

detecting peaks of the respiratory signal;

starting delay intervals with selected peaks of the detected peaks; and

delivering a burst of neural stimulation pulses when each of the delay intervals expires.

34. The method of claim 33, further comprising programming the delay interval to a time interval between approximately 0 and 5 seconds.

35. The method of claim 33, further comprising adjusting the delay interval using the respiratory signal.

36. The method of claim 35, wherein adjusting the delay interval using the respiratory signal comprises:

detecting a respiratory rate from the respiratory signal; and

calculating the delay interval as a function of the respiratory rate.

37. The method of claim 33, wherein receiving the respiratory signal comprises receiving a transthoracic impedance signal.

38. The method of claim 33, wherein receiving the respiratory signal comprises receiving a pulmonary artery pressure (PAP) signal.