Portable device for monitoring electrocardiographic signals and indices of blood flow

• US 20050267381A1
• Filed: 05/10/2005
• Published: 12/01/2005
• Est. Priority Date: 05/10/2004
• Status: Active Grant

• Current Assignee: Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Transoma Medical, Inc.
• Inventors: Lurie, Keith G., Benditt, David, Patterson, Robert
• Granted Patent: US 7,899,526 B2
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/026 Measuring blood flow A61B3/1233, A61B3/1241 take precedence
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/6837 Sutures

Abstract

Embodiments of the present invention are directed to a physiological monitoring device which is configured to record signals that reflect blood flow and/or blood pressure, and which may also record ECG signals. In one embodiment, a portable monitoring device comprises a plurality of impedance electrodes configured to be coupled to a patient'"'"'s body and to generate an AC current with an electrical field to detect local electrical impedance of a portion of the patient'"'"'s body encompassed by the electrical field, the local electrical impedance being a surrogate measure of local blood flow of the portion of the patient'"'"'s body. At least a portion of the portable monitoring device is configured to be insertable subcutaneously into the patient'"'"'s body.

Claims

1. A portable monitoring device comprising:

a plurality of impedance electrodes configured to be coupled to a patient'"'"'s body and to generate an AC current with an electrical field to detect local electrical impedance of a portion of the patient'"'"'s body encompassed by the electrical field, the local electrical impedance being a surrogate measure of local blood flow of the portion of the patient'"'"'s body; and

wherein at least a portion of the portable monitoring device is configured to be insertable subcutaneously into the patient'"'"'s body.

2. The portable monitoring device of claim 1 wherein the impedance electrodes are to be placed in proximity to a target region of the patient'"'"'s body to be monitored.

3. The portable monitoring device of claim 2 wherein the impedance electrodes are to be placed within less than about 5 cm of the target region of the patient'"'"'s body to be monitored.

4. The portable monitoring device of claim 1 wherein the impedance electrodes are configured to detect local electrical impedance near an artery in the patient'"'"'s body.

5. The portable monitoring device of claim 4 wherein the impedance electrodes include two electrodes that are spaced from one another in a direction generally parallel to the artery.

6. The portable monitoring device of claim 4 wherein the impedance electrodes include two electrodes that are spaced from one another in a direction generally transversely across the artery.

7. The portable monitoring device of claim 1 further comprising a temperature sensor configured to measure local tissue temperature of the patient'"'"'s body near the temperature sensor.

8. The portable monitoring device of claim 1 further comprising a plurality of ECG electrodes configured to be coupled to the patient'"'"'s body.

9. The portable monitoring device of claim 1 further comprising a battery.

10. The portable monitoring device of claim 1 further comprising a telemetry component configured to communicate telemetrically with an external device.

11. The portable monitoring device of claim 1 further comprising a warning component to provide warning based on the detected information.

12. The portable monitoring device of claim 1 wherein the impedance electrodes are can-mounted surface electrodes.

13. The portable monitoring device of claim 12 further comprising auxiliary leads coupled with the impedance electrodes.

14. The portable monitoring device of claim 1 further comprising a memory configured to store physiological information obtained by detecting the local electrical impedance by the impedance electrodes.

15. The portable monitoring device of claim 14 wherein the memory is configured to store data based on instructions delineating criteria for data to be stored.

16. The portable monitoring device of claim 14 wherein the memory has looping memory capability.

17. The portable monitoring device of claim 14 wherein the memory is configured to store data temporally proximate to an event based on information detected by the impedance electrodes or patient-activated triggering.

18. A portable monitoring device comprising:

a plurality of impedance electrodes configured to be coupled to a patient'"'"'s body and to generate an AC current with an electrical field to detect local electrical impedance of a portion of the patient'"'"'s body encompassed by the electrical field; and

a plurality of ECG electrodes configured to be coupled to the patient'"'"'s body.

19. The portable monitoring device of claim 18 further comprising a temperature sensor configured to measure local tissue temperature of the patient'"'"'s body near the temperature sensor.

20. The portable monitoring device of claim 18 further comprising a telemetry component configured to communicate telemetrically with an external device.

21. The portable monitoring device of claim 18 wherein the impedance electrodes and the ECG electrodes are can-mounted surface electrodes.

22. The portable monitoring device of claim 21 further comprising auxiliary leads coupled with at least some of the impedance electrodes and the ECG electrodes.

23. A method of monitoring a patient, the method comprising:

coupling a plurality of impedance electrodes to a patient'"'"'s body to generate an AC current with an electrical field to detect local electrical impedance of a portion of the patient'"'"'s body encompassed by the electrical field, the local electrical impedance being a surrogate measure of local blood flow of the portion of the patient'"'"'s body; and

inserting at least a portion of a portable monitoring device including the impedance electrodes subcutaneously into the patient'"'"'s body.

24. The method of claim 23 wherein the impedance electrodes are placed in proximity to a target region of the patient'"'"'s body to be monitored.

25. The method of claim 24 wherein the impedance electrodes are placed within less than about 5 cm of the target region of the patient'"'"'s body to be monitored.

26. The method of claim 23 wherein the impedance electrodes are applied to a muscle of the patient'"'"'s body to be monitored.

27. The method of claim 23 further comprising positioning two of the impedance electrodes near an artery and spacing the impedance electrodes in a direction generally parallel to the artery.

28. The method of claim 23 further comprising positioning two of the impedance electrodes near an artery and spacing the impedance electrodes in a direction generally transverse across the artery.

29. The method of claim 23 further comprising measuring local tissue temperature of the patient'"'"'s body.

30. The method of claim 23 further comprising measuring ECG data of the patient.

31. The method of claim 23 further comprising transferring information obtained by the impedance electrodes to an external device disposed outside the patient'"'"'s body.

32. The method of claim 23 further comprising generating a warning based on the detected information.

33. The method of claim 23 further comprising storing physiological information obtained by detecting the local electrical impedance by the impedance electrodes.

34. The method of claim 33 wherein the information is stored based on instructions delineating criteria for data to be stored.

35. The method of claim 33 wherein the information is stored proximate to an event based on information detected by the impedance electrodes or patient-activated triggering.

36. The method of claim 23 further comprising coupling auxiliary leads to the impedance electrodes and positioning the auxiliary leads in a target location in the patient'"'"'s body.