Dynamic Sampling

• US 20080027502A1
• Filed: 07/28/2006
• Published: 01/31/2008
• Est. Priority Date: 07/28/2006
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Ransom, Scott A.
• Granted Patent: US 8,688,219 B2
• Time in Patent Office: Days
• US Class Current: 607/42
• CPC Class Codes: A61B 5/036 by means introduced into body tracts A61B5/032 and A61B5/035 take precedence
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/4519 Muscles A61B5/389, A61B5/224 take precedence
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61N 1/3601 of respiratory organs

Abstract

Dynamic sampling of physiological parameters based on the next anticipated occurrence of a relatively periodic physiological event. Embodiments of the invention may be used to increase the battery life or effective data storage capacity of implantable medical devices while retaining or improving measurement resolution.

Claims

1. A method of operating an implantable medical device, comprising:

sensing a physiological parameter of a patient and producing a representative signal thereof, the physiological parameter including a periodically repeating physiological event;

sampling the sensed signal at a selected sampling frequency to produce digital samples representative of the sensed signal;

detecting the physiological events based on the digital samples;

determining an expected time period between the physiological events; and

setting the selected sampling frequency, the selected sampling frequency being increased ahead of an expected time of each physiological event based on the expected time period between physiological events, the selected sampling frequency being decreased following detection of each event.

2. A method according to claim 1, further comprising delivering a therapy to the patient at the expected time of each physiological event.

3. A method according to claim 1, further comprising delivering a therapy to the patient after detection of each physiological event.

4. A method according to claim 3, wherein the therapy includes electrical stimulation of upper airway muscles of the patient.

5. A method according to claim 1, wherein the physiological parameter includes an intrathoracic pressure in the patient.

6. A method according to claim 1, wherein the periodically repeating physiological event includes respiratory inspiration.

7. A method according to claim 1, wherein the determining the expected time period is based on the detection of the physiological events.

8. A method according to claim 1, further including detecting the frequency that the sensor signal crosses a measurement threshold value, the determining the expected time period between the physiological events being based on the frequency that the sensor signal crosses the measurement threshold value.

9. A method according to claim 1, wherein the increase of the selected sampling frequency includes increasing the sample frequency linearly with respect to time on the approach of the expected time of each physiological event.

10. A method according to claim 1, wherein the increase of the selected sampling frequency includes increasing the sample frequency exponentially with respect to time on the approach of the expected time of each physiological event.

11. A method according to claim 1, wherein the increase of the selected sampling frequency includes rapidly increasing the sampling frequency on the approach of the expected time of each physiological event.

12. A method according to claim 1, wherein the selected sampling frequency consists of first and second sampling frequencies, the second sampling frequency being higher than the first sampling frequency, the setting the sampling frequency being between the first and second sampling frequencies.

13. An implantable medical device, comprising:

an implantable sensor for sensing a physiological parameter of a patient and producing a representative signal thereof, the physiological parameter providing an indication of respiration;

an analog-to-digital converter for producing digital samples representative of the sensor signal at a sampling frequency; and

a processing means for detecting the indication of respiration based on the digital samples and for determining an expected time period between the indications of respiration, wherein said processor means sets and increases frequency being prior to an expected time of each indication of respiration.

14. A method according to claim 13, wherein the processor reduces the sampling frequency after the indication of respiration.

15. A method according to claim 13, further comprising a therapy delivery device coupled to the implantable sensor said device confirmed to deliver a therapy after detection of the indication of respiration.

16. A method according to claim 15, wherein the therapy delivery device comprises a laryngeal pacer.

17. A method according to claim 15, wherein the sensor is selected from a group consisting of a pressure sensor, an impedance sensor, a strain gauge.

18. A method of operating an implantable medical device, comprising:

sensing a physiological parameter of a patient and producing a representative signal thereof, the physiological parameter including a periodically repeating physiological event;

sampling the sensed signal at a selected sampling frequency to produce a plurality of digital samples representative of the sensed signal;

determining an expected signal period of the sensor signal, the expected signal period being determined based on the amount of time between crossings of a threshold by the sensor signal, the expected signal period corresponding to the period between the periodically repeating physiological events;

determining an expected time of each physiological event within each signal period; and

setting the selected sampling frequency, the selected sampling frequency being increased ahead of an expected time of each physiological event, the selected sampling frequency being decreased following a detection of each event.

19. A method according to claim 18, further comprising detecting the occurrence of each physiological event.

20. A method according to claim 19, wherein the detection of the occurrence of each physiological event is based at in part on the plurality of digital samples of the sensed signal.