Logging daily average metabolic activity using a motion sensor

• US 20090069720A1
• Filed: 09/12/2007
• Published: 03/12/2009
• Est. Priority Date: 09/12/2007
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Beck, Kenneth, Wariar, Ramesh, Carlson, Gerrard M., Kawahara, Chie
• Granted Patent: US 9,254,100 B2
• Time in Patent Office: Days
• US Class Current: 600/587
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/4866 Evaluating metabolism A61B5/083 takes precedence

Abstract

An implantable activity detector can detect metabolic stress levels, which can be normalized, such as to identify times of activities such as walking and running or to identify trends such as a decrease in metabolic activity. The data can be derived from different sources such as an accelerometer and pedometer. This data can be compared to independently specifiable thresholds, such as to trigger an alert or responsive therapy, or to display one or more trends. The information can also be combined with other congestive heart failure (CHF) indications. The alert can notify the patient or a caregiver, such as via remote monitoring. Metabolic activity data from one or more of the activity detectors can be used to establish a model of metabolic stress, to which further activity data can be compared for identifying periods of increased or decreased metabolic stress.

Claims

1. A system comprising:

an activity detector, configured to detect physical activity indication of a subject; and

a processor circuit, coupled to the activity detector, the processor configured to analyze exertion data from the activity detector, the processor configured to determine a metabolic stress indicator derived from an integration or area under the curve calculation of the measured exertion data occurring during the physical activity within a time period.

2. The system of claim 1, wherein the processor is configured to provide a normalized average metabolic equivalent indication to a user or automated process.

3. The system of claim 2, comprising a trending module, operatively coupled to the activity detector and processor circuit, the trending module configured to trend normalized average metabolic equivalent indication occurring two or more times within a specified duration.

4. The system of claim 1, wherein the activity detector is configured to detect a period of sustained physical activity exceeding a specified exertion level and a specified duration.

5. The system of claim 4, wherein the specified exertion level comprises at least 20 mGs.

6. The system of claim 4, wherein the specified duration comprises at least three minutes.

7. The system of claim 1, wherein the activity detector is configured to determine a total number of steps per day.

8. The system of claim 1, wherein the activity detector is configured to determine a daily average MET using measured exertion data wherein the exertion data is obtained in increments of less than one minute.

9. The system of claim 1, comprising an alert module, operatively coupled to the activity detector and processor circuit, the alert module configured to generate an alert indication in response to a change in value of at least one of the exertion data or the normalized average metabolic equivalent indication, wherein the change in value occurs at least once within a specified time duration.

10. The system of claim 9, wherein the specified time duration comprises at least two days.

11. A method comprising:

detecting physical activity of a subject within a time period;

computing exertion data using the detected physical activity within the period; and

determining a metabolic stress indicator derived from an indication of an integration or area under the curve of the exertion data over the period.

12. The method of claim 11, comprising providing a normalized average metabolic equivalent indication to a user or process.

13. The method of claim 12, comprising trending the normalized average metabolic equivalent indication.

14. The method of claim 11, wherein detecting physical activity comprises detecting a period of sustained physical activity exceeding a specified exertion level and a specified duration.

15. The method of claim 14, wherein the specified exertion level comprises at least 20 mGs.

16. The method of claim 14, wherein the specified duration comprises at least three minutes.

17. The method of claim 11, comprising determining a step rate derived from an averaged acceleration measurement of the subject movement over the period.

18. The method of claim 11, comprising deriving a metabolic equivalent (MET) from an acceleration within the period.

19. The method of claim 11, wherein determining a metabolic stress indicator comprises deriving a step total energy derived from the detected physical activity within the period.

20. The method of claim 11, comprising measuring at least one physiological parameter during the detected physical activity of the subject, wherein the measured physiological parameter varies with physical activity of the subject, and reporting the physiological parameter measurement to a user or automated process.

21. The method of claim 11, wherein providing a normalized average metabolic equivalent indication comprises deriving a number representative of average metabolic equivalent (MET) over the period.

22. The method of claim 11, comprising generating an alert in response to a change in value of at least one of the exertion data or the normalized average metabolic equivalent indication, wherein the change in value occurs at least once within a specified time duration.

23. The method of claim 22, wherein the specified time duration comprises at least two days.

24. The method of claim 11, wherein determining a metabolic stress indicator comprises deriving a value representative of a population.

25. The method of claim 11, wherein determining a metabolic stress indicator comprises deriving a value representative of the subject.