Portable cardiac monitor including a range limiter

• US 20060229523A1
• Filed: 04/08/2005
• Published: 10/12/2006
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: Exelys LLC
• Original Assignee: Exelys LLC
• Inventors: Barr, Keith E.
• Granted Patent: US 7,474,914 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 5/332 Portable devices specially adapted therefor
• CPC Class Codes: A61B 5/335 using integrated circuit memory devices

Abstract

A system and method for obtaining ECG signals from an ambulatory patient are disclosed herein. The system is configured to be inexpensive, small, and robust for outpatient monitoring. The system is configured to be a low power consuming device. The system provides options for a variety of settings and real-time access to the ECG signals being recorded during the recording period.

Claims

1. A method for processing patient physiological signals, the method comprising:

obtaining physiological signals from a patient;

performing an analog-to-digital conversion of the obtained physiological signals;

monitoring for an out-of-range condition of the obtained physiological signals; and

providing a correction signal to cause subsequently obtained physiological signals to be within range.

2. The method of claim 1, wherein the physiological signals are ECG signals.

3. The method of claim 1, wherein performing an analog-to-digital conversion comprises:

modulating the obtained physiological signals; and

decimating the modulated obtained physiological signals.

4. The method of claim 3, wherein the modulating comprises nth order delta sigma modulating the obtained physiological signals, where n=1 to 5.

5. The method of claim 3, wherein the modulating comprises oversampling the obtained physiological signals.

6. The method of claim 1, wherein monitoring comprises monitoring for a prescribed succession of digital values associated with the obtained physiological signals.

7. The method of claim 6, wherein monitoring comprises monitoring for a prescribed succession of 1'"'"'s.

8. The method of claim 6, wherein monitoring comprises monitoring for a prescribed succession of 0'"'"'s.

9. The method of claim 6, wherein the prescribed succession comprises a series of between 5 to 128 same values.

10. The method of claim 1, wherein providing a correction signal comprises providing a positive or negative current of a certain magnitude in accordance with the monitored out-of-range condition.

11. The method of claim 1, comprising correcting the subsequently obtained physiological signals within less than a data sampling period.

12. The method of claim 11, wherein correcting the subsequently obtained physiological signals comprises adjusting a baseline level associated with the subsequently obtained physiological signals.

13. A range limiter circuitry included in a portable electrocardiogram (ECG) recorder, the circuitry comprising:

an oversampling converter configured to receive electrical potential signals from a patient;

a decimator coupled to the oversampling converter; and

a feedback loop including;

a detector coupled to an output of the oversampling converter; and

a first current source coupled to an output of the detector, wherein an output of the first current source is coupled to the oversampling converter.

14. The circuitry of claim 13, comprising a capacitor provided between the patient and the oversampling converter.

15. The circuitry of claim 14, wherein the feedback loop is configured to affect a charge of the capacitor.

16. The circuitry of claim 13, wherein the oversampling converter comprises an nth order delta sigma modulator, where n=1 to 5.

17. The circuitry of claim 13, comprising a second current source coupled to the output of the detector and an output of the second current source forms the feedback loop to the oversampling converter.

18. The circuitry of claim 17, wherein the first current source comprises a positive current source and the second current source comprises a second current source.

19. The circuitry of claim 13, wherein the detector is configured to detect a preset number of 1'"'"'s or 0'"'"'s associated with the received electrical potential signals.

20. The circuitry of claim 13, wherein the first current source is configured to output a positive current when the detector detects a preset number of 1'"'"'s.

21. The circuitry of claim 13, wherein the first current source is configured to output a negative current when the detector detects a preset number of 0'"'"'s.

22. The circuitry of claim 13, wherein the feedback loop is configured to cause the output of the decimator to be within diagnostically useful range within less than a data sampling period after the detector detects an out-of-range condition for the received electrical potential signals.

23. A portable electrocardiogram (ECG) recorder, comprising:

means for detecting ECG data from an ambulatory patient;

means for detecting annotation data from the ambulatory patient, wherein the ECG data is different from the annotation data and the annotation data is configured for the ambulatory patient to additionally pinpoint potential cardiac events; and

means for providing the ECG data in a diagnostically useful form irrespective of an out-of-range condition associated with the ECG data.

24. The recorder of claim 23, wherein the ECG data is obtained non-invasively from a chest region of the ambulatory patient.

25. The recorder of claim 23, wherein the means for detecting annotation data comprises a notation device provided on a surface of the recorder.

26. The recorder of claim 23, wherein the means for detecting annotation data is actuated one or more times by the ambulatory patient during a recording period.

27. The recorder of claim 23, wherein the means for providing comprises a clip detector.

28. The recorder of claim 23, wherein the means for providing corrects for the out-of-range condition associated with the ECG data within a data sampling period.

29. The recorder of claim 23, wherein the means for providing comprises:

a capacitor;

a modulator coupled to the capacitor;

a decimator coupled to the modulator;

a detector coupled to the modulator;

a positive current source coupled to each of the detector and the capacitor; and

a negative current source coupled to each of the detector and the capacitor.

30. The recorder of claim 29, wherein the modulator comprises an oversampling converter.

31. The recorder of claim 29, wherein the modulator comprises an nth order delta-sigma modulator, where n=1 to 5.

32. The recorder of claim 29, wherein a bit rate associated with an output of the decimator is smaller than a bit rate associated with an output of the modulator.

33. The recorder of claim 23, wherein the means for providing is configured to detect a prescribed number of successive 1'"'"'s or 0'"'"'s representative of the ECG data.

34. The recorder of claim 33, wherein the prescribed number of successive 1'"'"'s or 0'"'"'s is a range between 5 and 128.