Medical Device Automatic Start-up Upon Contact to Patient Tissue

• US 20090076336A1
• 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: Bly, Mark J., Mazar, Scott T.
• Granted Patent: US 8,897,868 B2
• Time in Patent Office: Days
• US Class Current: 600/300
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 2560/0214 of power generation or supply
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/282 Holders for multiple electrodes for introduction into the body A61B5/287
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/68335 including release sheets or liners
• CPC Class Codes: A61B 5/6843 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61B 5/6885 Monitoring or controlling sensor contact pressure
• CPC Class Codes: A61N 1/36125 Details of circuitry or electric components
• CPC Class Codes: A61N 1/36139 with automatic adjustment
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/378 Electrical supply

Abstract

Methods and devices for monitoring and/or treating patients comprise a switch to automatically start-up the device when the device contacts tissue. By automatically starting up the device, the device may be installed without the clinician and/or user turning on the device, such that the device can be easy to use. In many embodiments, the device comprises startup circuitry with very low current and/or power consumption, for example less than 100 pA. The startup circuitry can detect tissue contact and turn on circuitry that is used to monitor or treat the patient.

Claims

1. A device for at least one of monitoring or treating a patient, the patient having a tissue, the device comprising:

a battery;

circuitry to at least one of monitor or treat the patient;

at least two electrodes configured to couple to the tissue of the patient; and

at least one switch coupled to the at least two electrodes, the battery and the circuitry, the at least one switch configured to detect tissue coupling to the at least two electrodes and connect the battery to the circuitry in response to tissue coupling to the at least two electrodes.

2. The device of claim 1, further comprising start-up circuitry, the start-up circuitry comprising the at least one switch, and wherein the at least one switch closes to connect the battery to the circuitry to at least one of monitor or treat the patient.

3. The device of claim 2 wherein the circuitry to at least one of monitor or treat the patient and the at least one switch comprise a low power configuration when the at least one switch is open and a high power configuration when the at least one switch is closed.

4. The device of claim 2 wherein the start-up circuitry and the circuitry to at least one of monitor or treat the patient are configured to draw a first amount of current from the battery when the at least one switch is open and a second amount of current when the at least one switch is closed and wherein the first amount of current is no more than about one tenth of the second amount of current.

5. The device of claim 2 wherein the start-up circuitry and the circuitry to at least one of monitor or treat the patient are configured to draw no more than about 0.5 μ

A from the battery when the at least one switch is open and wherein the start-up circuitry and the circuitry to at least one of monitor or treat the patient are configured to draw at least about 5 μ

A from the battery when the at least one switch is closed.

6. The device of claim 1, further comprising a voltage regulator and wherein the at least one switch and the voltage regulator are connected in series between the battery and the circuitry to at least one of monitor or treat the patient, such that the at least one switch and the voltage regulator connect the battery to the circuitry to at least one of monitor or treat the patient.

7. The device of claim 1, wherein the at least one switch comprises an open configuration to disconnect the battery from the circuitry to at least one of monitor or treat the patient.

8. The device of claim 7, wherein no more than about 0.5 μ

A of current passes from the battery when the switch is in the open configuration.

9. The device of claim 8, wherein the at least two electrodes are configured to couple to a skin of the patient.

10. The device of claim 7, wherein no more than about 0.1 μ

A of current passes from the battery when the switch is in the open configuration.

11. The device of claim 8, wherein the at least two electrodes are configured to couple to an internal tissue of the patient.

12. The device of claim 7, wherein no more than about 100 pA of current passes from the battery when the switch is in the open configuration.

13. The device of claim 1, wherein the at least one switch comprises a closed configuration to connect the battery to the circuitry to at least one of monitor or treat the patient in response to tissue coupling to the at least two electrodes.

14. The device of claim 13, wherein the at least about 100 uA of current passes from the battery when the at least one switch comprises the closed configuration and connects the battery to the circuitry to at least one of monitor or treat the patient.

15. The device of claim 1, wherein the at least one switch comprises a voltage divider and a transistor having a gate with a threshold voltage and wherein the voltage divider and the threshold voltage are configured to close the least one switch when a impedance between the at least two electrodes is below a threshold tissue detection impedance.

16. The device of claim 1, wherein the device comprises an implantable device configured to contact the tissue with the at least two electrodes.

17. The device of claim 16, one of the at least two electrodes comprises a housing of the implantable device.

18. The device of claim 1, wherein the tissue comprises skin and further comprising at least two gel pads in contact with the at least two electrodes to couple the at least two electrodes to the skin of the patient.

19. The device of claim 1, wherein the at least one switch is configured to connect the battery to the circuitry when the at least one switch detects an impedance between the at least two electrodes below a threshold impedance, and wherein the threshold impedance is within a range from about 2 k-Ohms to about 2 G-Ohm.

20. The device of claim 19, wherein the electrodes are configured to couple to a skin of the patient.

21. The device of claim 19, wherein the threshold impedance comprises a resistance within a range from 2 k-Ohms to 2 G-Ohm.

22. The device of claim 21, wherein the range is from about 100 k-Ohms to about 1 G-Ohm.

23. The device of claim 1, wherein the at least one switch is configured to connect the battery to the circuitry when the at least one switch detects an impedance between the at least two electrodes below a threshold impedance, and wherein the threshold impedance comprises at least about 100 Ohms.

24. The device of claim 23, wherein the at least two electrodes are configured to couple to an internal tissue of the patient.

25. The device of claim 1, wherein the tissue comprises skin having a skin impedance when the at least two electrodes are coupled to the skin and further comprising a removable liner having a liner impedance when the liner is coupled between the at least two electrodes, and wherein the liner impedance is greater than the skin impedance.

26. The device of claim 25, wherein the liner impedance comprises impedance between the at least two electrodes when the removable liner is positioned over the at least two electrodes.

27. The device of claim 25, wherein the liner impedance comprises a liner resistance and the skin impedance comprises a skin resistance and wherein the liner resistance is greater than the skin resistance.

28. The device of claim 25, wherein the liner comprises a substantially waterproof material.

29. The device of claim 25, wherein the liner comprises a cross-sectional thickness and a resistivity and the at least two electrodes comprise a separation distance such that the resistance between the at least two electrodes comprises at least about 10 M-Ohms when the liner is coupled to the at least two electrodes.

30. The device of claim 25, wherein the liner impedance comprises at least about 50 M-Ohms.

31. The device of claim 30, wherein the liner impedance comprises a resistance of at least about 50 M-Ohms.

32. The device of claim 31, wherein the liner resistance comprises at least about 1 G-Ohm.

33. The device of claim 25, wherein the liner comprises at least one piece.

34. The device of claim 33, wherein the liner comprises at least two pieces, the at least two pieces comprising a first liner piece and a second liner piece, the at least two electrodes comprising a first electrode and a second electrode, and wherein the first liner piece is positioned over the first electrode and the second liner piece is positioned over the second electrode and wherein the first liner piece and the second liner piece at least partially overlap between the first electrode and the second electrode.

35. The device of claim 25, further comprising at least two conductive gel pads disposed between the at least two electrodes and the liner, each of the at least two conductive gel pads in contact with one of the at least two electrodes and wherein the at least two conductive gel pads are separated to minimize electrical conductance between the at least two electrodes.

36. The device of claim 35, wherein each of the at least two conductive gel pads comprises a solid gel material to separate the at least two conductive gel pads.

37. The device of claim 35, further comprising a support comprising breathable tape affixed to each of the at least two electrodes, the breathable tape comprising an adhesive layer extending between the at least two electrodes and wherein the liner contacts the adhesive layer and the at least two gel pads and wherein the liner is configured to separate from the adhesive layer and the at least two gel pads to expose the adhesive layer and the at least two gel pads for placement against the skin.

38. The device of claim 37, wherein the support comprising the breathable tape and the adhesive layer comprises an impedance between the at least two electrodes and wherein the impedance of the support between the at least two electrodes and the impedance of the liner between the at least two electrodes are each greater the impedance of the skin when the skin is coupled to the at least two electrodes with the gel pads.

39. The device of claim 38, wherein the electrical impedance of the support comprises at least about 10 M-Ohm between the at least two electrodes and the electrical impedance of the liner comprises at least about 10 M-Ohm between the at least two electrodes.

40. The device of claim 39, wherein the electrical impedance of the support comprises at least about 1 G-Ohm between the at least two electrodes and the electrical impedance of the liner comprises at least about 1 G-Ohm between the at least two electrodes.

41. The device of claim 37, wherein the liner comprises a low stick surface to seal separately each of the at least two conductive gel pads between the support and the liner when the low stick surface of the liner is placed against the adhesive such that conductance between the at least two conductive gel pads is minimized.

42. The device of claim 37, further comprising a sealed foil packaging to contain the battery, the circuitry, the at least two electrodes, the at least one switch, the breathable support and the gel pads so as to maintain hydration of the gel pads in storage and wherein the breathable support comprises an impedance of at least about 10 M-Ohms between the at least two electrodes when sealed with the gel pads.

43. The device of claim 1, further comprising a load coupled to the battery when the at least one switch is open and wherein the load draws no more than about 1 uA of current from the battery when the at least one switch is open.

44. The device of claim 43, wherein the load comprises a clock coupled to the battery when the at least one switch is open, the clock comprising current date and time information when the at least one switch is open, and wherein the circuitry is configured to couple to the clock when the at least one switch is closed to time stamp data measured with the circuitry.

45. The device of claim 1, wherein the circuitry to at least one of monitor or treat the patient comprises the circuitry to monitor the patient.

46. The device of claim 1, wherein the circuitry to at least one of monitor or treat the patient comprises the circuitry to treat the patient.

47. A device for monitoring and/or treating a patient, the patient having a tissue, the device comprising:

a battery;

sensor circuitry configured to measure and/or treat the patient;

processor circuitry coupled to the sensor circuitry and configured to at least one of monitor or treat the patient;

at least two electrodes configured to couple to the tissue of the patient;

start-up circuitry comprising at least one switch coupled to the at least two electrodes, the battery, the sensor circuitry and the processor circuitry, the at least one switch configured to detect tissue contact with the at least two electrodes and connect the battery to the sensor circuitry and the processor circuitry in response to tissue contact with the at least two electrodes; and

sustain circuitry comprising at least one switch to connect the battery to the processor circuitry and the sensor circuitry in response to a signal from the processor.

48. The device of claim 47 wherein the at least one switch of the start-up circuitry and the at least one switch of the sustain circuitry are configured in parallel between the battery and at least one of the sensor circuitry and processor circuitry.

49. The device of claim 47 wherein the sustain circuitry is capable of sustaining a connection from the battery to the processor circuitry and the sensor circuitry after the tissue is removed from the electrodes and the at least one switch of the start-up circuitry opens.

50. The device of claim 47 wherein the sustain circuitry is capable of disconnecting the battery from the processor circuitry and the sensor circuitry after the tissue is removed from the electrodes and the at least one switch of the start-up circuitry opens.

51. The device of claim 47 wherein the processor circuitry is configured to detect disconnection of the tissue from the at least two electrodes.

52. The device of claim 51 wherein the processor circuitry is configured to transmit data from the sensor circuitry to a remote center in response to disconnection of the tissue from the at least two electrodes.

53. The device of claim 51 wherein the processor circuitry is configured to transmit a signal to a remote center in response to disconnection of the tissue from the electrodes to inform the remote center that tissue has been disconnected from the electrodes.

54. A method of monitoring and/or treating a patient having a tissue, the method comprising:

providing a device comprising circuitry to at least one of monitor or treat the patient, the device comprising a battery and electrodes; and

contacting the electrodes with the tissue to deliver power from the battery to the circuitry.

55. The method of claim 54 wherein at least one switch closes to connect the circuitry to the battery when the tissue contacts the electrodes.

56. The method of claim 54 wherein at least one switch opens to disconnect the circuitry from the battery when the tissue is removed from the electrodes.

57. The method of claim 54 further comprising removing the tissue from the electrodes and wherein the battery is disconnected from the circuitry to turn off the circuitry in response to removing the tissue from the circuitry.

58. The method of claim 54 further comprising removing the tissue from the electrodes and wherein a signal is sent to a remote center in response to removing the tissue from the electrodes.

59. A method of manufacturing a device to at least one of monitor or treat a patient, the patient having a tissue, the method comprising:

manufacturing sensor circuitry, start-up circuitry and electrodes, the electrodes coupled to the start-up circuitry and sensor circuitry, the start-up circuitry comprising at least one switch configured to detect tissue contact with the electrodes;

installing batteries in the device; and

shipping the device with the batteries installed and the device configured such that the start-up circuitry is capable of turning on the device when electrodes of the device contact the tissue of the patient.

60. The method of claim 59 wherein the device comprises a processor and wherein the start-up circuitry is configured to turn on the sensor circuitry and the processor when the electrodes contact the tissue.

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

providing a device comprising a support, batteries, sensor circuitry, start-up circuitry, at least two electrodes and at least two gel pads in contact with the at least two electrodes, the batteries coupled to the startup circuitry, the electrodes coupled to the start-up circuitry and sensor circuitry, the start-up circuitry comprising at least one switch and configured to detect tissue coupling to the at least two electrodes, wherein the support comprises an adhesive and is configured to support the batteries, the sensor circuitry, the at least two electrodes and the at least two gel pads with the skin of the patient and wherein the removable liner covers the adhesive and the at least two gel pads;

separating a removable liner from the adhesive and the at least two gel pads to expose the adhesive and the at least two gel pads; and

placing the adhesive and the at least two gel pads against the skin of the patient to adhere the device to the patient and couple the electrodes to the skin, wherein the start up circuitry closes an electrical switch to start the sensor circuitry with power from the battery when the at least two gel pads contact the skin of the patient.