Sensing techniques for implantable medical devices

• US 20040215265A1
• Filed: 04/23/2003
• Published: 10/28/2004
• Est. Priority Date: 04/23/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Keizer, Diederick M.
• Granted Patent: US 7,319,899 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/4809 Sleep detection, i.e. determining whether a subject is asleep or not

Abstract

The invention is directed to sensing techniques that can be executed by an implantable medical device (IMD). The sensing techniques exploit the fact that useful information can be sensed during the periods where the sympathetic and vagal tone balance changes in a patient'"'"'s nervous system. This balance generally changes when a patient is falling asleep or waking up from sleep. In accordance with the invention, sensed information is recorded specifically during the times where a patient is either falling asleep or waking up. The IMD can be designed to sense or identify when a patient is falling asleep or waking up, and can record the useful sensed information specifically during those times.

Claims

1. An implantable medical device comprising:

a sensor implanted within a patient;

a controller coupled to the sensor; and

a memory coupled to the controller, wherein the controller identifies that a patient is going to sleep and records in the memory information sensed by the sensor for a time interval associated with the patient going to sleep.

2. The implantable medical device of claim 1, wherein the controller detects that the patient is going to sleep by receiving a signal triggered by the patient.

3. The implantable medical device of claim 1, wherein the controller detects that the patient is going to sleep by receiving heart rate information sensed by the sensor and detecting a reduction in the heart rate below a heart rate threshold.

4. The implantable medical device of claim 1, wherein the controller detects that the patient is going to sleep by receiving respiratory rate information sensed by the sensor and detecting a reduction in the respiratory rate below a respiratory rate threshold.

5. The implantable medical device of claim 1, wherein the controller detects that the patient is going to sleep by receiving an indication of positioning of the patient relative to the ground.

6. The implantable medical device of claim 1, wherein the controller identifies that a patient is waking up and records information sensed by the sensor in the memory for a time interval associated with the patient waking up.

7. The implantable medical device of 6, wherein the controller detects that the patient is waking up by receiving heart rate information sensed by the sensor and detecting an increase in the patient'"'"'s heart rate above a heart rate threshold.

8. The implantable medical device of 6, wherein the controller detects that the patient is waking up by receiving respiratory rate information sensed by the sensor and detecting an increase in the patient'"'"'s respiratory rate above a respiratory rate threshold.

9. An implantable medical device comprising:

a controller;

a memory coupled to the controller;

a heart sensor coupled to the controller;

a respiratory sensor coupled to the controller; and

a position sensor coupled to the controller, wherein the controller identifies that a patient is going to sleep based on information received from the respective sensors and records in the memory information sensed by one or more of the sensors for a time interval associated with the patient going to sleep.

10. The implantable medical device of claim 9, further comprising a telemetry unit coupled to the controller to receive a programmable value establishing the time interval associated with the patient going to sleep.

11. The implantable medical device of claim 9, wherein the controller identifies that a patient has gone to sleep based on information received from the respective sensors and terminates recording of sensed information once the patient has gone to sleep.

12. The implantable medical device of claim 9, wherein the controller detects that a patient is going to sleep by identifying at least two of the following:

a reduction in heart rate below a heart rate threshold;

a reduction in respiratory rate below a respiratory rate threshold; and

an indication that the patient is lying down based on positioning of the position sensor.

13. The implantable medical device of claim 9, wherein the controller detects that the patient is waking up based on information received from the respective sensors and records information sensed by one or more of the sensors in the memory for a time interval associated with the patient waking up.

14. The implantable medical device of claim 13, wherein the controller detects that a patient is waking up by:

identifying an increase in heart rate above a heart rate threshold; and

identifying an increase in respiratory rate above a respiratory rate threshold.

15. The implantable medical device of claim 9, further comprising a therapy delivery device couple to the controller, wherein the controller controls delivery of therapy by the therapy delivery device based on the information sensed by one or more of the sensors and recorded in the memory for the defined time interval associated with the patient going to sleep.

16. A method comprising:

detecting that a patient is going to sleep; and

recording information sensed by an implantable medical device for a time interval associated with the patient going to sleep.

17. The method of claim 16, wherein detecting that a patient is going to sleep includes receiving a signal triggered by the patient.

18. The method of claim 16, wherein detecting that a patient is going to sleep includes identifying a reduction in heart rate below a heart rate threshold.

19. The method of claim 16, wherein detecting that a patient is going to sleep includes identifying a reduction in respiratory rate below a respiratory rate threshold.

20. The method of claim 16, wherein detecting that a patient is going to sleep includes identifying positioning of the implantable medical device relative to the ground.

21. The method of claim 16, wherein detecting that a patient is going to sleep includes at least two of the following:

identifying a reduction in heart rate below a heart rate threshold;

identifying a reduction in respiratory rate below a respiratory rate threshold; and

identifying that a patient is lying down based on positioning of the implantable medical device relative to the ground.

22. The method of claim 16, further comprising receiving a programmable value defining the time interval associated with the patient going to sleep.

23. The method of claim 16, further comprising dynamically establishing the time interval by:

detecting that a patient has gone to sleep; and

terminating the recording of information sensed by the implantable medical device once the patient has gone to sleep.

24. The method of claim 16, further comprising:

detecting that a patient is waking up; and

recording information sensed by the implantable medical device for a defined time interval associated with the patient waking up.

25. The method of claim 24, wherein detecting that a patient is waking up includes identifying an increase in heart rate above a heart rate threshold.

26. The method of claim 24, wherein detecting that a patient is waking up includes identifying an increase in respiratory rate above a respiratory rate threshold.

27. The method of claim 24, further comprising receiving a programmable value establishing the defined time interval associated with the patient waking up.

28. The method of claim 16, further comprising telemetrically communicating the recorded information to another device.

29. The method of claim 16, further comprising providing therapy to the patient based on the recorded information.

30. The method of claim 16, wherein detecting that the patient is going to sleep includes identifying a first trigger of sensed information to initiate the recording and identifying a second trigger of sensed information to verify that the patient is going to sleep following the initiation of the recording.

31. An implantable medical device comprising:

means for detecting that a patient is going to sleep; and

means for recording information sensed by the implantable medical device for a time interval associated with the patient going to sleep.

32. The implantable medical device of claim 31, wherein the means for detecting that the patient is going to sleep includes:

means for detecting a reduction in heart rate below a heart rate threshold;

means for detecting a reduction in respiratory rate below a respiratory rate threshold; and

means for detecting positioning of the implantable medical device relative to the ground.

33. The implantable medical device of claim 31, further comprising means for receiving a programmable value defining the time interval associated with the patient going to sleep.

34. The implantable medical device of claim 31, further comprising:

means for detecting that a patient is waking up; and

means for recording information sensed by the implantable medical device for a defined time interval associated with the patient waking up.

35. The implantable medical device of claim 34, wherein the means for detecting that the patient is waking up includes:

means for detecting an increase in heart rate above a heart rate threshold; and

means for detecting an increase in respiratory rate above a respiratory rate threshold.

36. A method comprising:

detecting that a patient is waking up from sleep; and

recording information sensed by an implantable medical device for a time interval associated with the patient waking up.