Method for providing a therapy to a patient involving modifying the therapy after detecting an onset of sleep in the patient, and implantable medical device embodying same

• US 20020193839A1
• Filed: 06/07/2001
• Published: 12/19/2002
• Est. Priority Date: 06/07/2001
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Jensen, Donald N., Mongeon, Luc R., Cho, Yong Kyun
• Granted Patent: US 6,731,984 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration

Abstract

An implantable medical device system is described including an implantable medical device for implantation in a patient. One embodiment of the implantable medical device includes a therapy component for providing a therapy to the patient, a minute ventilation (MV) sensing circuit producing MV values indicative of a MV of the patient at time intervals, and computational circuitry. The computational circuitry receives a number of the MV values over a period of time, calculates a statistical parameter (e.g., a mean) of the MV values, and calculates a deviation of the MV values from the statistical parameter (e.g., a standard deviation of the MV values). The computational circuitry detects an onset of sleep in the patient when the deviation of the MV values from the statistical parameter is less than a predetermined MV threshold value, and signals the therapy component to modify the therapy when the onset of sleep is detected in the patient. A method is disclosed for providing therapy to a patient, including detecting an onset of sleep in the patient, and modifying the therapy following the detecting the onset of sleep in the patient.

Claims

1. An implantable medical device for implantation in a patient, comprising:

a therapy component configured to provide a therapy to the patient;

a minute ventilation sensing circuit configured to produce minute ventilation values indicative of a minute ventilation of the patient at time intervals;

computational circuitry coupled to the therapy component and the minute ventilation sensing circuit and configured to receive a plurality of the minute ventilation values over a period of time, to calculate a statistical parameter of the minute ventilation values, to calculate a deviation of the minute ventilation values from the central tendency, to detect an onset of sleep in the patient when the deviation of the minute ventilation values from the statistical parameter is less than a predetermined minute ventilation threshold value, and to signal the therapy component to modify the therapy when the onset of sleep is detected in the patient.

2. The implantable medical device as recited in claim 1, wherein the computational circuitry is configured to calculate the statistical parameter of the minute ventilation values by calculating a mean of the minute ventilation values.

3. The implantable medical device as recited in claim 2, wherein the computational circuitry is configured to calculate the deviation of the minute ventilation values from the statistical parameter by calculating a standard deviation of the minute ventilation values.

4. The implantable medical device as recited in claim 3, wherein the computational circuitry is configured to detect the onset of sleep in the patient when the standard deviation of the minute ventilation values is less than the minute ventilation threshold value.

5. The implantable medical device as recited in claim 1, further comprising an activity sensing circuit configured to produce activity values indicative of an activity level of the patient at time intervals, wherein the computational circuitry is coupled to receive the activity values.

6. The implantable medical device as recited in claim 5, wherein the computational circuitry is configured to detect the onset of sleep in the patient when:

(i) the deviation of the minute ventilation values from the statistical parameter is less than the predetermined minute ventilation threshold value, and (ii) an activity value indicative of a current level of activity of the patient is less than an activity threshold value.

7. The implantable medical device as recited in claim 5, wherein the computational circuitry is configured to keep track of a time of day, and wherein the computational circuitry is configured to detect the onset of sleep in the patient when:

(i) the deviation of the minute ventilation values from the statistical parameter is less than the predetermined minute ventilation threshold value, and (ii) an activity value indicative of a current level of activity of the patient is less than an activity threshold value, and (iii) a current time of day is greater than or equal to an expected sleep time value, wherein the expected sleep time value is indicative of a time of day the patient is expected to go to sleep.

8. An implantable pacemaker for implantation in a patient, comprising:

a pacing output unit configurable to provide electrical stimulation to a portion of a heart of the patient dependent upon a low rate limit value, wherein the low rate limit value specifies a minimum rate of sensed contractions of the portion of the heart;

a minute ventilation sensing circuit configured to produce minute ventilation values indicative of a minute ventilation of the patient at time intervals;

computational circuitry coupled to the pacing output unit and the minute ventilation sensing circuit and configured to receive a plurality of the minute ventilation values over a period of time, to calculate a central tendency of the minute ventilation values, to calculate a deviation of the minute ventilation values from the central tendency, to detect an onset of sleep in the patient when the deviation of the minute ventilation values from the central tendency is less than a predetermined minute ventilation threshold value, and to reduce the low rate limit value when the onset of sleep is detected in the patient.

9. The implantable pacemaker as recited in claim 8, wherein the computational circuitry is configured to calculate the central tendency of the minute ventilation values by calculating a mean of the minute ventilation values.

10. The implantable pacemaker as recited in claim 9, wherein the computational circuitry is configured to calculate the deviation of the minute ventilation values from the central tendency by calculating a standard deviation of the minute ventilation values.

11. The implantable pacemaker as recited in claim 10, wherein the computational circuitry is configured to detect the onset of sleep in the patient when the standard deviation of the minute ventilation values is less than the minute ventilation threshold value.

12. The implantable pacemaker as recited in claim 8, further comprising an activity sensing circuit configured to produce activity values indicative of an activity level of the patient at time intervals, wherein the computational circuitry is coupled to the therapy component, the minute ventilation sensing circuit, and the activity sensing circuit.

13. The implantable pacemaker as recited in claim 12, wherein the computational circuitry is configured to detect the onset of sleep in the patient when:

(i) the deviation of the minute ventilation values from the central tendency is less than the predetermined minute ventilation threshold value, and (ii) an activity value indicative of a current level of activity of the patient is less than an activity threshold value.

14. The implantable pacemaker as recited in claim 12, wherein the computational circuitry is configured to keep track of a time of day, and wherein the computational circuitry is configured to detect the onset of sleep in the patient when:

(i) the deviation of the minute ventilation values from the central tendency is less than the predetermined minute ventilation threshold value, and (ii) an activity value indicative of a current level of activity of the patient is less than an activity threshold value, and (iii) a current time of day is greater than or equal to an expected sleep time value, wherein the expected sleep time value is indicative of a time of day the patient is expected to go to sleep.

16. The method as recited in claim 15, wherein calculating the central tendency comprises calculating a mean of the minute ventilation values.

17. The method as recited in claim 16, wherein calculating the deviation of the minute ventilation values from the central tendency comprises calculating a standard deviation of the minute ventilation values.

18. The method as recited in claim 17, wherein detecting the onset of sleep comprises detecting the onset of sleep in the patient if the standard deviation is less than the minute ventilation threshold value.

19. The method as recited in claim 15, further comprising receiving an activity value indicative of a current level of activity of the patient, and wherein detecting the onset of sleep comprises detecting the onset of sleep in the patient if:

(i) the deviation of the minute ventilation values from the central tendency is less than the predetermined minute ventilation threshold value, and (ii) the activity value is less than an activity threshold value.

20. The method as recited in claim 15, further comprising receiving an activity value indicative of a current level of activity of the patient, and wherein detecting the onset of sleep comprises detecting the onset of sleep in the patient if:

(i) the deviation of the minute ventilation values from the central tendency is less than the predetermined minute ventilation threshold value, and (ii) the activity value is less than an activity threshold value, and (iii) a current time of day is greater than or equal to an expected sleep time, wherein the expected sleep time is a time of day the patient is expected to go to sleep.

15. A method for providing therapy to a patient, comprising:

detecting an onset of sleep in the patient, comprising;

receiving a plurality of minute ventilation values over a period of time, wherein the minute ventilation values are indicative of a minute ventilation of the patient;

calculating a central tendency of the minute ventilation values;

calculating a deviation of the minute ventilation values from the central tendency; and

detecting the onset of sleep in the patient if the deviation of the minute ventilation values from the central tendency is less than a predetermined minute ventilation threshold value; and

modifying the therapy following the detecting the onset of sleep in the patient.

21. A method for providing therapy to a patient, comprising:

detecting an onset of sleep in the patient, comprising;

receiving a first plurality of minute ventilation values over a first period of time, wherein the minute ventilation values are indicative of a minute ventilation of the patient;

using the first plurality of minute ventilation values to determine a minute ventilation threshold value;

receiving a second plurality of minute ventilation values over a second period of time following the first period of time;

calculating a central tendency of the second plurality of minute ventilation values;

calculating a deviation of the second plurality of minute ventilation values from the central tendency; and

detecting the onset of sleep in the patient if the deviation of the second plurality of minute ventilation values from the central tendency is less than the minute ventilation threshold value; and

modifying the therapy following the detecting the onset of sleep in the patient.

22. The method as recited in claim 21, wherein receiving the first plurality of minute ventilation values comprises:

receiving a first plurality of minute ventilation values over a first period of time, wherein the minute ventilation values are indicative of a minute ventilation of the patient, and wherein the first period of time is greater than or equal to 24 hours.

23. The method as recited in claim 22, wherein using the first plurality of minute ventilation values to determine the minute ventilation threshold value comprises:

receiving a number of the first plurality of minute ventilation values during each of a plurality of time intervals of the first period of time;

calculating for each time interval;

a central tendency of the minute ventilation values received during the time interval; and

a deviation of the minute ventilation values received during the time interval from the central tendency;

forming a histogram of the deviations of the minute ventilation values received during the time intervals from the central tendencies;

locating a pair of peaks in the histogram; and

selecting an minute ventilation value residing between the peaks in the histogram as the minute ventilation threshold value.

24. The method as recited in claim 23, wherein calculating for each time interval comprises:

calculating for each time interval;

a mean of the minute ventilation values received during the time interval; and

a standard deviation of the minute ventilation values received during the time interval.

25. The method as recited in claim 24, wherein forming the histogram comprises forming a histogram of the standard deviations of the minute ventilation values received during the time intervals.

26. The method as recited in claim 21, further comprising receiving an activity value indicative of a current level of activity of the patient, and wherein detecting the onset of sleep comprises detecting the onset of sleep in the patient if:

(i) the deviation of the second plurality of minute ventilation values from the central tendency is less than the minute ventilation threshold value, and (ii) the activity value is less than an activity threshold value.

27. The method as recited in claim 21, further comprising receiving an activity value indicative of a current level of activity of the patient, and wherein detecting the onset of sleep comprises detecting the onset of sleep in the patient if:

(i) the deviation of the second plurality of minute ventilation values from the central tendency is less than the minute ventilation threshold value, and (ii) the activity value is less than an activity threshold value, and (iii) a current time of day is greater than or equal to an expected sleep time, wherein the expected sleep time is a time of day the patient is expected to go to sleep.

29. The method as recited in claim 28, wherein calculating the central tendency comprises calculating a mean of the minute ventilation values.

30. The method as recited in claim 29, wherein calculating the deviation of the minute ventilation values from the central tendency comprises calculating a standard deviation of the minute ventilation values.

31. The method as recited in claim 30, wherein detecting the onset of sleep comprises detecting the onset of sleep in the patient if the standard deviation is less than the minute ventilation threshold value.

32. The method as recited in claim 28, further comprising receiving an activity value indicative of a current level of activity of the patient, and wherein detecting the onset of sleep comprises detecting the onset of sleep in the patient if:

(i) the deviation of the minute ventilation values from the central tendency is less than the predetermined minute ventilation threshold value, and (ii) the activity value is less than an activity threshold value.

33. The method as recited in claim 28, further comprising receiving an activity value indicative of a current level of activity of the patient, and wherein detecting the onset of sleep comprises detecting the onset of sleep in the patient if:

(i) the deviation of the minute ventilation values from the central tendency is less than the predetermined minute ventilation threshold value, and (ii) the activity value is less than an activity threshold value, and (iii) a current time of day value is greater than or equal to an expected sleep time, wherein the expected sleep time is a time of day the patient is expected to go to sleep.

35. The implantable medical device as recited in claim 34, wherein the means for detecting is configured to calculate the central tendency of the minute ventilation values by calculating a mean of the minute ventilation values.

36. The implantable medical device as recited in claim 34, wherein the means for detecting is configured to calculate the deviation of the minute ventilation values from the central tendency by calculating a standard deviation of the minute ventilation values.

28. A method for providing electrical stimulation to a heart of a patient, comprising:

detecting an onset of sleep in the patient, comprising;

receiving a plurality of minute ventilation values over a period of time, wherein the minute ventilation values are indicative of a minute ventilation of the patient;

calculating a central tendency of the minute ventilation values;

calculating a deviation of the minute ventilation values from the central tendency; and

detecting the onset of sleep in the patient if the deviation of the minute ventilation values from the central tendency is less than a predetermined minute ventilation threshold value; and

reducing a low rate limit following the detecting the onset of sleep in the patient, wherein electrical stimulation is provided to a portion of the heart if a sensed rate of contractions of the portion of the heart falls below the low rate limit.

34. An implantable medical device for implantation in a patient, comprising:

means for detecting an onset of sleep in the patient, wherein the detecting means is configured to;

(i) receive a plurality of minute ventilation values over a period of time, wherein the minute ventilation values are indicative of a minute ventilation of the patient, (ii) calculate a central tendency of the minute ventilation values, (iii) calculate a deviation of the minute ventilation values from the central tendency, and (iv) generate a signal if the deviation of the minute ventilation values from the central tendency is less than a predetermined minute ventilation threshold value; and

means for providing a therapy to the patient, wherein the therapy means is coupled to receive the signal and configured to modify the therapy in response to the signal.