Method for continuous baroreflex sensitivity measurement

• US 20070179385A1
• Filed: 01/31/2006
• Published: 08/02/2007
• Est. Priority Date: 01/31/2006
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Cho, Yong, Bennett, Tommy
• Granted Patent: US 7,874,992 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence

Abstract

A medical device and method for determining baroreflex sensitivity (BRS) based on one or more respiration cycles. The BRS determination may be performed continuously based on measurements of heart rate, blood pressure, and respiration cycles.

Claims

1. A method for calculating a continuous baroreflex sensitivity (BRS) value, comprising:

detecting respiration cycles of a patient;

measuring heart rate of the patient over a first set of respiration cycles;

measuring a pressure metric of the patient over a second set of respiration cycles; and

calculating a BRS value based on the heart rate and pressure measurements.

2. A method according to claim 1, wherein the calculating the BRS value is performed for each respiration cycle.

3. A method according to claim 1, wherein the calculating the BRS value is based on heart rate and pressure measurements taken over different respiration cycles.

4. A method according to claim 1, wherein the respiration cycles are detected from the pressure measurement.

5. A method according to claim 1, wherein the measuring the pressure metric comprises measuring a right ventricular systolic pressure metric.

6. A method according to claim 1, wherein the calculating the BRS value includes determining a maximum change in the pressure metric over each respiration cycle.

7. A method according to claim 1, wherein calculating the BRS value includes determining a maximum change in an R-R interval over each respiration cycle.

8. A method according to claim 1, wherein the heart rate is measured from an ECG signal.

9. An implantable medical device, comprising:

one or more sensors for sensing patient heart rate, blood pressure, and respiration cycles; and

a housing supporting a processor and adapted for implantation in a patient, the processor coupled to the one or more sensors, the processor for calculating continuous baroreflex sensitivity (BRS) for each detected respiration cycle based on the sensed heart rate, blood pressure and respiration cycles.

10. A medical device according to claim 9, wherein the respiration cycles and blood pressure are sensed by the same one of the one or more sensors.

11. A medical device according to claim 9, wherein the processor calculates a trendline of BRS values obtained over multiple respiration cycles.

12. A medical device according to claim 9, wherein the processor compares the BRS calculation against a zone of predetermined BRS thresholds.

13. A medical device according to claim 12, wherein the processor initiates an alarm if the BRS calculation is outside the zone of predetermined BRS thresholds.

14. A medical device according to claim 12, wherein the processor changes at least one zone threshold if the BRS calculation intermittently produces values outside the zone.

15. A medical device according to claim 12, wherein the processor initiates a treatment if the BRS calculation is outside of the zone of predetermined thresholds.

16. A computer-readable medium programmed with instructions for baroreflex sensitivity (BRS) measurement, the medium comprising instructions for causing a programmable processor to:

detect at least one of inspiration and expiration cycles of a patient;

measure a heart rate of the patient;

measure a pressure of the patient; and

calculate a BRS value over that at least one of inspiration and expiration cycles, the BRS calculation constituting the change in measured heart rate divided by the change in measured pressure.

17. A medium according to claim 16, further comprising detecting a patient circumstance including at least one of patient activity, time of day, and patient posture, and classifying BRS measurement data based on the detected patient circumstance.

18. A medium according to claim 16, further comprising instructions to detect a patient circumstance including at least one of patient activity, time of day, and patient posture, and initiate BRS calculation after detection of the patient circumstance.

19. A medium according to claim 18, further comprising instructions to initiate the at least one of inspiration and expiration cycle detection, heart rate measurement, and pressure measurement after detection of the patient circumstance.

20. A medium according to claim 18, further comprising instructions to detect a change in the patient circumstance and to halt BRS calculation after detection of the change in the patient circumstance.

21. A medium according to claim 18, further comprising instructions to halt BRS calculation upon reaching a predetermined time period after initiating BRS calculation.

22. A medium according to claim 16, wherein the BRS calculations are performed by a medical device implanted in the patient.