Flexible memory management scheme for loop recording in an implantable device

• US 7,764,988 B2
• Filed: 04/27/2006
• Issued: 07/27/2010
• Est. Priority Date: 04/27/2006
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Drew, Touby A., Carlson, David L.
• Primary Examiner(s): Layno; Carl H
• Assistant Examiner(s): Porter, Jr.; Gary A
• Application Number:
  US11/380,590
• Publication Number:
  US 20070255147A1
• Time in Patent Office: 1,552 Days
• Field of Search: 600/523, 600/524, 600/544, 600/509, 600/515, 607/18
• US Class Current: 600/509
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/4094 Diagnosing or monitoring seizure diseases, e.g. epilepsy
• CPC Class Codes: A61B 5/7232 involving compression of the physiological signal, e.g. to extend the signal recording period

Abstract

A method and apparatus is provided for handling multiple recordings that result from events in a limited memory device. The events may include various automatic and manual triggers. The method provides a mechanism for storing different configurations of data, associated with different events.

Claims

1. A method of handling recordings in an implantable device, the method comprising:

(a) prioritizing data using a priority index, the priority index based on a severity level function, the data stored in data blocks of a fixed buffer;

(b) initiating a first recording in an active buffer, the first recording storing pre-event data associated from a signal set;

(c) detecting a first event and a type of the first event;

(d) determining a sensing configuration based on the type of the first event, the configuration specifying a time duration having a pre-event time and a post-event time that indicates a total amount of time to record data of the first event;

(e) copying the pre-event data associated with the first event beginning at the pre-event time into a data block of the fixed buffer having lowest priority data as determined in (a);

(f) saving post-event data associated with the first event until the post-event time in the data block of the fixed buffer including the pre-event data; and

(g) re-prioritizing data using the priority index, the data stored in data blocks of the fixed buffer.

2. The method of claim 1, wherein the active buffer comprises a circular buffer.

3. The method of claim 1, wherein the configuration specifies at least one of a plurality of channels to record based on the type of the first event.

4. The method of claim 1, wherein the active buffer is sized based on equation Active Buffer Size=(Maximum number of channels)*(Maximum Pre-event time).

5. The method of claim 1, wherein data stored in the fixed buffer is interleaved.

6. The method of claim 1, further comprising (h) initiating a second recording in the active buffer, the second recording storing pre-event data from a second signal set.

7. The method of claim 6, further comprising:

(i) detecting a second event;

(j) copying pre-event data associated with the second event into a data block having the second lowest priority data as determined in (g); and

(k) saving post-event data associated with the second event in the data block of the fixed buffer including the second pre-event data.

8. The method of claim 7, wherein the second event comprises a second trigger, the second trigger including an electrocardiogram trigger.

9. The method of claim 7, wherein the second event comprises a second trigger, the second trigger including a seizure detection algorithm trigger.

10. The method of claim 7, wherein the second event comprises a second trigger, the second trigger including a manual trigger.

11. The method of claim 1, wherein the first event comprises a first trigger, the first trigger including an electrocardiogram trigger.

12. The method of claim 1, wherein the first event comprises a first trigger, the first trigger including a seizure detection algorithm trigger.

13. The method of claim 1, wherein the first event comprises a first trigger, the first trigger including a manual trigger.

14. An implantable medical device comprising:

(a) a first monitoring element that receives a first signal set associated with a physiologic condition;

(b) a second monitoring element that receives a second signal set;

(c) a storage medium; and

(d) a processing module coupled to the storage medium and programmed with computer-executable instructions for performing;

(i) prioritizing data using a priority index, the priority index based on a severity level function, the data stored in data blocks of a fixed buffer;

(ii) initiating a first recording in an active buffer, the first recording storing pre-event data associated from a signal set;

(iii) detecting a first event and a type of the first event;

(iv) determining a sensing configuration based on the type of the first event, the configuration specifying a time duration having a pre-event time and a post-event time that indicates a total amount of time to record data of the first event;

(v) copying the pre-event data associated with the first event beginning at the pre-event time into a data block of the fixed buffer having lowest priority data as determined in (i);

(vi) saving post-event data associated with the first event until the post-event time in the data block of the fixed buffer including the pre-event data; and

(vii) re-prioritizing data using a priority index, the data stored in data blocks of the fixed buffer.

15. The device of claim 14, wherein the active buffer comprises a circular buffer.

16. The device of claim 14, further comprising (viii) initiating a second recording in the active buffer, the second recording storing pre-event data from a second signal set.

17. The device of claim 16, further comprising:

(ix) detecting a second event;

(x) copying pre-event data associated with the second event into a data block having the second lowest priority data a determined in (vii); and

(xi) saving post-event data associated with the second event in the data block of the fixed buffer including the second pre-event data of the second recording.