Data reduction of sensed values in an implantable medical device through the ...

United States Patent m

Woodson, in

US005709216A [li] Patent Number: [45] Date of Patent:

5,709,216 Jan. 20, 1998

[54] DATA REDUCTION OF SENSED VALUES IN AN IMPLANTABLE MEDICAL DEVICE THROUGH THE USE OF A VARIABLE RESOLUTION TECHNIQUE

[75] Inventor: Drury L. Woodson, HL Alvin, Tex.

[73] Assignee: Sulzer Interniedics, Inc., Angleton, Tex.

[21] Appl. No.: 478,473
[22] Filed: Jun. 7,1995

[51] Int CI.6 A61B 5/04

[52] U.S. CI 128/710; 128/673; 128/736;

128/637

[58] Field of Search 128/695 R, 696,

128/706, 710, 711, 637, 673, 736; 364/413.02, 413.03, 413.04, 413.05, 413.06; 607/19-23, 59; 382/128, 232, 239, 244, 246

[56] References Cited

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Primary Examiner—Jeffrey R. Jastrzab

Attorney, Agent, or Firm—Conley, Rose, & Tayon, PC;

Michael F. Heim

[57] ABSTRACT

An implantable device which acquires physiological data and status information. The physiological data is compressed, reducing the memory requirement of the implantable device and/or increasing the amount of data that can be stored. The compression technique uses variable resolution while maintaining desired accuracy. The physiological data, such as heart beat interval time, is converted into a digital value. The digital representation then is divided into sub-ranges, and various resolution values are assigned to each sub-range. Each resolution is selected to stay within the desired accuracy. The interval time is divided by the particular resolution to obtain a digital value for the interval time within that range. The digital value then is corrected based upon the sub-range to obtain the compressed encoded digital value, which can then be stored in memory together with other desired data.

44 Claims, 4 Drawing Sheets