Adherent Cardiac Monitor with Advanced Sensing Capabilities

• US 20090076340A1
• Filed: 09/12/2008
• Published: 03/19/2009
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: Medtronic Monitoring, Inc. (Medtronic Plc)
• Original Assignee: Corventis
• Inventors: Fogoros, Rich, Manicka, Yatheendhar D., Libbus, Imad
• Granted Patent: US 8,460,189 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/061 Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body A61B1/00158 takes precedence
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/282 Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/327 Generation of artificial ECG signals based on measured signals, e.g. to compensate for missing leads
• CPC Class Codes: A61B 5/332 Portable devices specially adapted therefor
• CPC Class Codes: A61B 5/4869 Determining body composition
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/684 Indicating the position of the sensor on the body
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: G01C 9/06 Electric or photoelectric indication or reading means

Abstract

An adherent device comprises an adhesive patch with at least two electrodes and an accelerometer. The accelerometer can be used to determine an orientation of the at least two measurement electrodes on a patient. By determining the orientation of the electrodes of the patch on the patient, physiologic measurements with the at least two electrodes can be adjusted and/or corrected in response to the orientation of the patch on the patient. The adherent patch and/or electrodes can be replaced with a second adherent patch and/or electrodes, and the orientation of the second adherent patch and/or electrodes can be determined with the accelerometer or a second accelerometer. The determined orientation of the second patch and/or electrodes on the patient can be used to correct measurements made with the second adherent patch and/or electrodes.

Claims

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

adhering an adherent device to a skin of the patient, the adherent device comprising an accelerometer and at least two measurement electrodes, the at least two measurement electrodes separated by a distance to define an electrode measurement axis;

measuring an accelerometer signal when the device is adhered to the patient; and

determining an orientation of the electrode measurement axis on the patient in response to the accelerometer signal.

2. The method of claim 1 wherein the accelerometer comprises at least one measurement axis sensitive to gravity aligned with the electrode measurement axis.

3. The method of claim 1 wherein the accelerometer comprises at least one accelerometer measurement axis sensitive to gravity, the at least one accelerometer measurement axis configured to extend substantially horizontally on the patient when the device is adhered to the patient.

4. The method of claim 1 wherein the accelerometer signal correspond to at least one accelerometer measurement vector in a direction along the at least one accelerometer measurement axis.

5. The method of claim 1 wherein the accelerometer comprises at least one accelerometer measurement axis sensitive to gravity and wherein the at least one accelerometer measurement axis is oriented with respect to the electrode measurement axis in a predetermined configuration.

6. The method of claim 1 wherein the at least two electrodes comprise a positive electrode and a negative electrode that define an orientation of an electrode measurement vector along the electrode measurement axis.

7. The method of claim 6 wherein the accelerometer signal corresponds to at least one accelerometer measurement vector that extends away from the electrode measurement axis and wherein the at least one accelerometer measurement vector is sensitive to gravity such that the accelerometer signal indicates when the patch adhered to the patient is upside down.

8. The method of claim 1 wherein the adherent device comprises an adherent surface to adhere to a skin of the patient and wherein the electrode measurement axis extends along the adherent surface.

9. The method of claim 1 wherein the accelerometer comprises three axes and wherein a first axis and a second axis of the three axes extend along the measurement surface and wherein a third axis of the three axes extends away from the measurement surface.

10. The method of claim 9 wherein the accelerometer measurement signal corresponds to three orthogonal measurement vectors and wherein each of the three orthogonal measurement vectors extends along one of the accelerometer measurement axes.

11. The method of claim 1 further comprising measuring an electrocardiogram signal with the at least two measurement electrodes and modifying the electrocardiogram signal in response to the accelerometer signal.

12. The method of claim 11 wherein modifying comprises rotating the electrocardiogram vector in response to the accelerometer signal to obtain a standard electrocardiogram vector.

13. The method of claim 12 wherein an amplitude and a direction of features of the electrocardiogram signal are modified to approximate a standard electrocardiogram vector.

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

adhering a first adherent patch to a skin of the patient, the first patch comprising an adhesive and electrodes;

measuring a first accelerometer signal when the first adherent patch is adhered to the patient;

adhering a second adherent patch to the skin of the patient, the second patch comprising an adhesive and electrodes;

measuring a second accelerometer signal when the second adherent patch is adhered to the patient; and

determining an orientation on the patient of at least one of the first patch or the second patch in response to at least one of the first accelerometer signal or the second accelerometer signal.

15. The method of claim 14 further comprising:

measuring a first electrocardiogram signal when the first adherent patch is adhered to the patient;

measuring a second electrocardiogram signal when the second adherent patch is adhered to the patient; and

adjusting at least one of the first electrocardiogram signal or the second electrocardiogram signal in response to at least one of the first accelerometer signal or the second accelerometer signal.

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

adhering a first adherent measurement device to a skin of the patient, the first adherent measurement device comprising a first accelerometer and a first at least two measurement electrodes;

adhering a second adherent measurement device to a skin of the patient, the second adherent measurement device comprising a second accelerometer and a second at least two measurement electrodes;

measuring a first accelerometer signal and a first electrocardiogram signal with the first at least two measurement electrodes when the first adherent measurement device is adhered to the skin of the patient;

measuring a second accelerometer signal and a second electrocardiogram signal with the second at least two measurement electrodes when the second adherent measurement device is adhered to the skin of the patient; and

combining the first electrocardiogram signal with the second electrocardiogram signal in response to the first accelerometer signal and the second accelerometer signal.

17. The method of claim 16 wherein the processor is configured to scale each of the first electrocardiogram signal and the second electrocardiogram signal to a scaled version of each signal and combine the scaled version of each signal to form a combined signal.

18. The method of claim 16 wherein the first accelerometer comprises a first accelerometer measurement axis and the first at least two electrodes are separated by a first distance to define a first electrode measurement axis, the first accelerometer measurement axis aligned with the first electrode measurement axis, and wherein the second accelerometer comprises a second accelerometer measurement axis and the second at least two electrodes are separated by a second distance to define a second electrode measurement axis, the second accelerometer measurement axis aligned with the second electrode measurement axis.

19. The method of claim 16 further comprising:

determining an orientation of the first electrode measurement axis in response to the first accelerometer signal; and

determining an orientation of the second electrode measurement axis in response to the to the accelerometer signal.

20. The method of claim 16 wherein the first electrocardiogram signal is combined with the second electrocardiogram signal when the second adherent measurement device is adhered to the skin of the patient.

21. A device for monitoring a patient, the device comprising:

a support with an adhesive to adhere to a skin of the patient;

an accelerometer to generate an accelerometer signal supported with the support;

at least two measurement electrodes supported with the support, the at least two measurement electrodes separated by a distance to define an electrode measurement axis;

circuitry to measure the accelerometer signal when the device is adhered to the patient; and

a processor comprising a tangible medium configured to determine an orientation of the electrode measurement axis on the patient in response to the accelerometer signal.

22. The device of claim 21 wherein the support comprises an adhesive patch with an adhesive to adhere the support to the patient.

23. The device of claim 22 wherein the adhesive patch comprises a breathable tape with adhesive to adhere the support to the patient.

24. The device of claim 21 wherein the accelerometer comprises at least one measurement axis sensitive to gravity aligned with the electrode measurement axis.

25. The device of claim 21 wherein the accelerometer comprises at least one accelerometer measurement axis sensitive to gravity and wherein the accelerometer is positioned and supported with the support such that the measurement axis extends substantially horizontally on the patient when the support is adhered to the patient.

26. The device of claim 21 wherein the accelerometer signal corresponds to at least one accelerometer measurement vector along the at least one accelerometer measurement axis.

27. The device of claim 21 wherein the accelerometer comprises at least one accelerometer measurement axis sensitive to gravity and wherein the at least one accelerometer measurement axis is oriented with respect to the electrode measurement axis in a predetermined configuration.

28. The device of claim 21 wherein the at least two electrodes comprise a positive electrode and a negative electrode that define an orientation of an electrode measurement vector along the electrode measurement axis.

29. The device of claim 28 wherein the accelerometer signal corresponds to at least one measurement vector that extends away from the electrode measurement axis such that the accelerometer signal indicates when the patch adhered to the patient is upside down.

30. The device of claim 21 wherein the adherent device comprises an adherent surface to adhere to a skin of the patient and wherein the electrode measurement axis extends along the adherent surface.

31. The device of claim 21 wherein the accelerometer comprises three axes and wherein a first axis and a second axis of the three axes extend along the adherent surface and wherein a third axis of the three axes extends away from the adherent surface.

32. The device of claim 21 wherein the accelerometer signal corresponds to three orthogonal measurement vectors and wherein each of the three orthogonal measurement vectors extends along one of the accelerometer measurement axes.

33. The device of claim 21 further comprising:

measurement circuitry coupled to the at least two measurement electrode to measure an electrocardiogram signal;

a processor coupled to the measurement circuitry and comprising a tangible medium configured to modify the electrocardiogram signal in response to the accelerometer signal.

34. A system for monitoring a patient, the system comprising:

a first support with a first adhesive to adhere the first support to a skin of the patient,

first electrodes supported with the first support to couple to the skin of the patient;

a second support with a second adhesive to adhere the second support to the skin of the patient,

second electrodes supported with the second support to couple to the skin of the patient;

at least one accelerometer coupled to at least one of the first support or the second support to determine an orientation of at least one of the first electrodes or the second electrodes when the at least one of the first electrodes or the second electrodes are coupled to the patient.

35. The system of claim 34 wherein the at least one accelerometer comprises a first accelerometer removably coupled to the first support in a first predetermined orientation and a second accelerometer removably coupled to the second support in a second predetermined orientation.

36. The system of claim 34 wherein the at least one accelerometer comprises an accelerometer removably coupled to the first support in a first predetermined orientation and wherein the accelerometer is removably coupled to the second support in a second predetermined orientation such that the accelerometer can be reused.

38. The system of claim 34 wherein the at least one accelerometer comprises a first accelerometer connected to the first support in a first predetermined orientation and a second accelerometer connected to the second support in a second predetermined configuration.

39. The system of claim 38 wherein first accelerometer is removably connected to the first support such the first accelerometer can be recharged and connected to a third support when first support is removed from the patient and wherein the second accelerometer is removably coupled to the second support such that the second accelerometer can be recharged and connected to a fourth support when the second support is removed from the patient.

40. The system of claim 38 wherein first accelerometer is affixed to the first support such the first accelerometer is disposable with first support when first support is removed from the patient and wherein the second accelerometer is affixed to the second support such that the second accelerometer is disposable with the second support when the second support is removed from the patient.

41. The system of claim 34 wherein the first support with the first adhesive comprises a first breathable tape and the second support with the second adhesive comprises a second breathable tape.

37. The system of claim 37 wherein the first predetermined orientation is substantially similar to the second predetermined orientation.

42. A system monitoring a patient, the system comprising:

a first adherent measurement device comprising a first support with a first adhesive to adhere the first support to a skin of the patient, the first adherent measurement device comprising a first accelerometer and a first at least two measurement electrodes, the first adherent device comprising first measurement circuitry to measure a first accelerometer signal with the accelerometer and a first electrocardiogram signal with the first at least two measurement electrodes;

a second adherent measurement device comprising a second support with a second adhesive to adhere the second support to a skin of the patient, the second adherent measurement device comprising a second accelerometer and a second at least two measurement electrodes, the second accelerometer comprising second circuitry to measure a second accelerometer signal with the second accelerometer and a second electrocardiogram signal with the second at least two measurement electrodes; and

a processor system comprising a tangible medium configured to combine the first electrocardiogram signal with the second electrocardiogram signal in response to the first accelerometer signal and the second accelerometer signal.

43. The system of claim 42 wherein the first accelerometer comprises a first accelerometer measurement axis and the first at least two electrodes are separated by a first distance to define a first electrode measurement axis, the first accelerometer measurement axis aligned with the first electrode measurement axis, and wherein the second accelerometer comprises a second accelerometer measurement axis and the second at least two electrodes are separated by a second distance to define a second electrode measurement axis, the second accelerometer measurement axis aligned with the second electrode measurement axis.

44. The system of claim 42 wherein the processor system is configured to determine an orientation of the first electrode measurement axis in response to the first accelerometer signal and determine an orientation of the second electrode measurement axis in response to the to the accelerometer signal.

45. The system of claim 42 wherein the processor system comprises at least one processor supported with at least one of the first support or the second support, the at least one processor configured to combine the first electrocardiogram signal and the second electrocardiogram signal in response to the first accelerometer signal and the second accelerometer signal.

46. The system of claim 42 wherein the processor is configured to scale each signal and sum the scaled signals together to combine the signals.