Source: http://www.google.com/patents/US20020193839?dq=6246862
Timestamp: 2017-10-18 02:02:21
Document Index: 385151284

Matched Legal Cases: ['art 110', 'art 110', 'art 110', 'art 110', 'art 110', 'art 110', 'art 110']

Patent US20020193839 - Method for providing a therapy to a patient involving modifying the therapy ... - Google Patents
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...http://www.google.com/patents/US20020193839?utm_source=gb-gplus-sharePatent US20020193839 - 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
Publication number US20020193839 A1
Also published as DE60203902D1, DE60203902T2, EP1395336A2, EP1395336B1, US6731984, WO2002100482A2, WO2002100482A3
Publication number 09876528, 876528, US 2002/0193839 A1, US 2002/193839 A1, US 20020193839 A1, US 20020193839A1, US 2002193839 A1, US 2002193839A1, US-A1-20020193839, US-A1-2002193839, US2002/0193839A1, US2002/193839A1, US20020193839 A1, US20020193839A1, US2002193839 A1, US2002193839A1
Inventors Yong Cho, Donald Jensen, Luc Mongeon
Original Assignee Cho Yong Kyun, Jensen Donald N., Mongeon Luc R.
Referenced by (143), Classifications (7), Legal Events (6)
US 20020193839 A1
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;
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.
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.
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.
21. A method for providing therapy to a 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
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:
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.
28. A method for providing electrical stimulation to a heart of a patient, comprising:
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.
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.
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.
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.
[0031]FIG. 1 is a diagram of one embodiment of an implantable medical device (IMD) system including a cardiac pacemaker, an atrial lead, and a ventricular lead implanted in a patient;
[0032]FIG. 2 is a diagram of one embodiment of the cardiac pacemaker of FIG. 1, wherein the pacemaker produces pacing pulses delivered to a heart of the patient of FIG. 1 via the atrial lead and the ventricular lead;
[0034]FIG. 4 is a flow chart of one embodiment of a method for providing a therapy to the patient, wherein the method involves determining an onset of sleep in the patient;
[0035]FIG. 5A is a histogram of minute ventilation values of a patient obtained via minute ventilation sensing circuitry over a 24-hour period;
[0036]FIG. 5B is a histogram of standard deviations of the minute ventilation values used to form the histogram of FIG. 4A and received within 1-minute time windows;
[0037]FIG. 6 is a graph of standard deviation values “MV Stdev Long” and “MV Stdev Short” calculated using minute ventilation values produced during 2-second time intervals and indicative of the minute ventilation of a patient; and
[0038]FIG. 7 is a graph of a standard deviation value “MV Stdev Long” calculated using minute ventilation values produced during 2-second time intervals and indicative of the minute ventilation of a patient.
[0041]FIG. 1 is a diagram of one embodiment of an implantable medical device (IMD) system 100 including a cardiac pacemaker 102, an atrial lead 104, and a ventricular lead 106 implanted in a patient 108. The pacemaker 102 produces electrical pulses (i.e., pacing pulses) that stimulate a heart 110 of the patient 108. One end of the atrial lead 104 is electrically coupled to the pacemaker 102, the other end of the atrial lead 104 extends through a vein 112 into a right atrium of the heart 110. One end of the ventricular lead 106 is electrically coupled to the pacemaker 102, the other end of the ventricular lead 106 extends through the vein 112 and into a right ventricle of the heart 110. Electrically conductive electrodes attached to the ends of the atrial lead 104 and the ventricular lead 106 located within the heart 110 are used to deliver pacing pulses to the heart 110, and to receive intrinsic electrical signals present within the heart 110.
[0044]FIG. 2 is a diagram of one embodiment of the cardiac pacemaker 102 of FIG. 1. As described above, the pacemaker 102 produces pacing pulses delivered to the heart 110 of the patient 108 (FIG. 1) via the atrial lead 104 and the ventricular lead 106. In the embodiment of FIG. 2, the pacemaker 102 includes lead interface circuitry 200, pacing output circuitry 202, a central processing unit (CPU) 204, a memory 206, timing/pacing control circuitry 208, a minute ventilation (MV) sensing circuit 210, an activity sensing circuit 212, a telemetry unit 214, and an antenna 216.
Regarding the determining of the second minute ventilation value, the CPU 204 FIG. 2) of the pacemaker 102 (FIGS. 1-2) may keep a running estimate of a mean value (i.e., an average value) of the received minute ventilation values. The mean value represents a “central tendency” of the received minute ventilation values. At the end of a predetermined time interval (i.e., after receiving a predetermined number of minute ventilation values), the CPU 204 may calculate a measure of deviation of the minute ventilation values received during the time interval from a “current” estimate of the mean value. The CPU 204 may form a histogram of the deviations of the minute ventilation values from the mean value.
[0097]FIG. 4 is a flow chart of one embodiment of a method 400 for providing a therapy to a patient (e.g., the patient 108 of FIG. 1). The method 400 may be embodied within software residing in the memory 206 (FIG. 2) of the pacemaker 102 (FIGS. 1-2). The CPU 204 (FIG. 2) may carry out the method 400 when executing the software embodying the method 400. During a first step 402 of the method 400, an onset of sleep is determined in the patient. The step 402 of the method 400 may be accomplished by carrying out the steps of the method 300 of FIGS. 3A-3D. During a step 404, the therapy provided to the patient is modified.
[0103]FIGS. 5A and 5B will now be used to further describe the calculation of the second minute ventilation threshold value. FIG. 5A is a histogram of minute ventilation values of a patient obtained via minute ventilation sensing circuitry over a 24-hour period. In obtaining data for the histogram of FIG. 5A, minute ventilation sensing circuitry delivered current pulses at a rate of 16 Hz, thereby defining pulse “cycles” having “cycle times” of {fraction (1/16)} or 0.0625 seconds. The minute ventilation sensing circuitry converted an analog difference voltage between a “current” value of a thoracic impedance signal, obtained during a “current” pulse cycle, and a “previous” value of the thoracic impedance signal, obtained during a pulse cycle immediately preceding the current pulse cycle, to a digital “count” value. The minute ventilation sensing circuitry summed 32 of the digital “count” values produced by the analog-to-digital conversion circuitry in a register over predefined 2-second time intervals. At the end of each 2-second time interval, the minute ventilation sensing circuitry produced a “minute ventilation value” contained in the register, and the register is cleared.
[0105]FIG. 5B is a histogram of standard deviations of the minute ventilation values used to form the histogram of FIG. 5A and received within 1-minute time windows. As described above, the minute ventilation sensing circuitry produced a new minute ventilation value at the end of each 2-second time interval. A running estimate of a mean of the minute ventilation values was updated each time a new minute ventilation value was produced by the minute ventilation sensing circuitry as described above. At the end of each 1-minute time window, ending with a 2-second time interval k, a mean value estimate Mean(k) was calculated using the minute ventilation values received during the current time interval and an immediately preceding 29 time intervals (i.e., p=30) as described above, and the standard deviation of the 30 minute ventilation values received during the time window was calculated using: MVStdev = ∑ j = 1 30   ( MV  ( k - 30 - j ) - Mean  ( k ) ) 2 30
[0109]FIG. 6 is a graph of “MV Stdev Long” and “MV Stdev Short” values described above, wherein the “MV Stdev Long” and “MV Stdev Short” values were calculated using minute ventilation values produced during 2-second time intervals and indicative of the minute ventilation of a patient. In FIG. 6, the first minute ventilation threshold value described above defines an “MV Threshold 1” level, and the second minute ventilation threshold value described above defines an “MV Threshold 2” level. As illustrated in FIG. 6, the “MV Threshold 1” level is greater than the “MV Threshold 2” level. As described above, the first minute ventilation threshold value is used to screen a received minute ventilation value to determine if the received minute ventilation value is sufficiently low as to warrant further analysis to detect an onset of sleep.
[0111]FIG. 7 is a graph of “MV Stdev Long” values described above, wherein the “MV Stdev Long” values were calculated using minute ventilation values produced during 2-second time intervals and indicative of the minute ventilation of a patient. As in FIG. 6, the first minute ventilation threshold value described above defines a level labeled “MV Threshold 1,” and the second minute ventilation threshold value described above defines a level labeled “MV Threshold 2.”
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U.S. Classification 607/17, 607/11