Devices and methods for monitoring physiological information relating to sleep with an implantable device
View Patent ↗Described here are implantable devices and methods for monitoring physiological information relating to sleep. The implantable devices are generally designed to include at least one sensor for sensing physiological information, a processor for processing the physiological information using low computational power to detect a sleep stage, and a battery. The detected sleep stage information may then be used to indicate sleep quality, identify or monitor a medical condition, or guide treatment thereof.
1. A method of detecting a sleep state or sleep stage with an active implantable medical device, said method comprising:
determining first and second parameters of each of a plurality of half waves resulting from sensed physiological information;
for each of the plurality of half waves, determining that the half wave is a qualified half wave when the first parameter of the half wave satisfies a first criterion and the second parameter of the same half wave satisfies a second criterion, wherein each of the first criterion and the second criterion are defined by a respective minimum parameter and a respective maximum parameter;
counting a number of qualified half waves that occur during a time window; and
detecting a particular sleep state or stage when a measure derived from the number satisfies a third criterion indicative of the particular sleep state or stage.
2. The method of claim 1 , wherein:
the first parameter is a half-wave amplitude;
the minimum parameter of the first criterion is a minimum amplitude and the maximum parameter of the first criterion is a maximum amplitude; and
the first criterion is satisfied when a half-wave amplitude is between the minimum amplitude and the maximum amplitude.
3. The method of claim 1 , wherein:
the second parameter is a half-wave duration;
the minimum parameter of the second criterion a minimum duration and the maximum parameter of the first criterion is a maximum duration; and
the second criterion is satisfied when a half-wave duration is between the minimum duration and the maximum duration.
4. The method of claim 1 , wherein:
the measure derived from the number is an unsigned integer;
the third criterion is a threshold; and
the particular sleep state or stage is detected when the unsigned integer exceeds the threshold.
5. The method of claim 1 , wherein:
the measure derived from the number is an unsigned integer;
the third criterion is one of a range of unsigned integers; and
the particular sleep state or stage is detected when the unsigned integer falls within the range.
6. The method of claim 1 , wherein counting a number comprises:
classifying each qualified half wave as one of a plurality of half-wave types; and
for each of the plurality of half-wave types, determining a half-wave-type number corresponding to the number of qualified half waves classified as the half-wave type.
7. The method of claim 6 , wherein:
the measure derived from the number is a ratio of two of the half-wave type numbers;
the third criterion is a threshold; and
the particular sleep state or stage is detected when the ratio satisfies the threshold.
8. The method of claim 6 , wherein the plurality of half-wave types comprises at least two of the following half-wave types: alpha half-wave, delta half-wave and theta half-wave.
9. The method of claim 1 , wherein the particular sleep state or stage includes stage 1 sleep, stage 2 sleep, stage 3 sleep or stage 4 sleep.
10. An active implantable medical device for detecting a sleep state or sleep stage, said device comprising:
a sensor configured to sense physiological information; and
a processor connected to the sensor and configured to:
determine first and second parameters of each of a plurality of half waves resulting from sensed physiological information;
for each of the plurality of half waves, determine that the half wave is a qualified half wave when the first parameter of the half wave satisfies a first criterion and the second parameter of the same half wave satisfies a second criterion, wherein each of the first criterion and the second criterion are defined by a respective minimum parameter and a respective maximum parameter;
count a number of qualified half waves that occur during a time window; and
detect a particular sleep state or stage when a measure derived from the number satisfies a third criterion indicative of the particular sleep state or stage.
11. The device of claim 10 , wherein:
the first parameter is a half-wave amplitude;
the minimum parameter of the first criterion is minimum amplitude and the maximum parameter of the first criterion is a maximum amplitude; and
the first criterion is satisfied when a half-wave amplitude is between the minimum amplitude and the maximum amplitude.
12. The device of claim 10 , wherein:
the second parameter is a half-wave duration;
the minimum parameter of the second criterion a minimum duration and the maximum parameter of the first criterion is a maximum duration; and
the second criterion is satisfied when a half-wave duration is between the minimum duration and the maximum duration.
13. The device of claim 10 , wherein:
the measure derived from the number is an unsigned integer;
the third criterion is a threshold; and
the particular sleep state or stage is detected when the unsigned integer exceeds the threshold.
14. The device of claim 10 , wherein:
the measure derived from the number is an unsigned integer;
the third criterion is one of a range of unsigned integers; and
the particular sleep state or stage is detected when the unsigned integer falls within the range.
15. The device of claim 10 , wherein to count a number, the processor is configured to:
classify each qualified half wave as one of a plurality of half-wave types; and
for each of the plurality of half-wave types, determine a half-wave-type number corresponding to the number of qualified half waves classified as the half-wave type.
16. The device of claim 15 , wherein:
the measure derived from the number is a ratio of two of the half-wave type numbers;
the third criterion is a threshold; and
the particular sleep state or stage is detected when the ratio satisfies the threshold.
17. The device of claim 15 , wherein the plurality of half-wave types comprises at least two of the following half-wave types: alpha half-wave, delta half-wave and theta half-wave.
18. The device of claim 10 , wherein the particular sleep state or stage includes stage 1 sleep, stage 2 sleep, stage 3 sleep or stage 4 sleep.