Implantable medical device with circulation delay measurement and therapy control

• US 20050251218A1
• Filed: 09/21/2004
• Published: 11/10/2005
• Est. Priority Date: 05/07/2004
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Erickson, Mark K., Cho, Yong K., Sowelam, Sameh, Markowitz, H. Toby, Giese, Chad T., Jovanovic, Marina, Mehta, Pooja
• Granted Patent: US 7,315,759 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61N 1/3601 of respiratory organs
• CPC Class Codes: A61N 1/36557 controlled by chemical substances in blood

Abstract

Oxygen saturation data is monitored during a predefined window to obtain a measurement of circulation delay. The measured circulation delay is used as a basis for determining therapies, including overdrive pacing. In some embodiments, circulation delay is used to identify patients that will benefit from overdrive pacing as a therapy for sleep disordered breathing.

Claims

1. An implantable medical device comprising:

means for cardiac pacing;

means for sensing oxygen saturation levels;

means for sensing respiration; and

means for determining circulation delay based upon respiration and oxygen saturation levels.

2. The implantable medical device of claim 1, wherein the means for sensing oxygen saturation levels and the means for cardiac pacing are disposed within a common housing.

3. The implantable medical device of claim 1, further comprising:

telemetry means for enabling communication between the means for cardiac pacing and the means for sensing oxygen saturation.

4. The implantable medical device of claim 3, wherein the means for cardiac pacing are implanted remotely from the means for sensing oxygen saturation.

5. The implantable medical device of claim 1, further comprising means for evaluating the determined circulation delay and selectively enabling overdrive pacing based on the evaluation.

6. A method of determining circulation delay comprising:

establishing a duration for an apnea/hyperventilation window;

monitoring for an apnea;

initiating the established hyperventilation window at the termination of the apnea;

monitoring oxygen saturation levels during the window;

identifying the nadir of oxygen saturation during the window; and

calculating circulation delay as a time interval between the initiation of the window and the nadir.

7. The method of claim 6, wherein the hyperventilation window is patient specific.

8. The method of claim 6, wherein the hyperventilation window is established based on an averaged value of a predetermine number of apnea/hyperventilation episodes.

9. A method of identifying patients receptive to overdrive pacing as a therapy for sleep disordered breathing, the method comprising:

measuring circulation delay;

comparing the measured circulation delay to an expected value;

determining a variance between the measured circulation delay and the expected value; and

identifying the patient as a candidate for overdrive pacing if the variance exceeds a first predetermined threshold.

10. The method of claim 9, further comprising:

evaluating comorbidities that would respond to a reduction in circulation delay;

identifying the patient as a candidate for overdrive pacing as a therapy for one or more of the comorbidities if the variance exceeds a second predetermined threshold.

11. A method of measuring circulation delay comprising:

obtaining oxygen saturation data from an implanted oximeter;

providing the oxygen saturation data to a circulation delay module of an implantable medical device;

providing respiration data to the circulation delay module; and

calculating circulation delay within the circulation delay module based upon the respiration data and oxygen saturation data.

12. The method of claim 11, further comprising:

establishing a duration for an apnea/hyperventilation window;

monitoring for an apnea;

initiating the established hyperventilation window at the termination of the apnea; and

identifying the nadir of oxygen saturation during the window, wherein, calculating circulation delay includes determining a time interval between the initiation of the window and the nadir.

13. An implantable medical device system comprising:

an implantable pulse generator;

a controller coupled with the implantable pulse generator and selectively providing pacing stimuli;

an oximeter;

a circulation delay module communicatively coupled with the controller and the oximeter and providing a measurement of circulation delay to the controller, wherein the controller selectively provides pacing based upon the measurement of circulation delay.

14. The implantable medical device system of claim 13, further comprising a housing including the implantable pulse generator, the controller, the oximeter and the circulation delay module.

15. The implantable medical device system of claim 13, wherein the oximeter is externally positioned and communicatively coupled with the circulation delay module via telemetry.

16. The implantable medical device system of claim 13, further comprising a respiration sensor communicatively coupled with the circulation delay module.

17. The implantable medical device system of claim 16, wherein the respiration sensor senses a termination of an apnea that initiates an observation window for the oximeter.

18. The implantable medical device system of claim 13, wherein the oximeter senses a lowest oxygen saturation point during the window and communicates that point to the circulation delay module.

19. The implantable medical device system of claim 13, wherein the controller initiates overdrive pacing if the measurement of circulation delay exceeds a predetermined threshold.