Patient-worn energy delivery apparatus

• US 6,280,461 B1
• Filed: 06/28/1999
• Issued: 08/28/2001
• Est. Priority Date: 05/23/1996
• Status: Expired due to Term

• Current Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Original Assignee: Zoll Lifecor Corporation (Asahi Kasei Corporation)
• Inventors: Kaib, Thomas E., Peduzzi, David J., Russial, Joseph, Glegyak, John A.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US09/340,357
• Time in Patent Office: 792 Days
• Field of Search: 607/5, 607/6
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3904 External heart defibrillators [EHD]
• CPC Class Codes: A61N 1/3912 Output circuitry therefor, e.g. switches
• CPC Class Codes: A61N 1/3937 Monitoring output parameters

Abstract

A patient-worn energy delivery apparatus for imparting electrical therapy to the body of a patient responsive to an occurrence of a treatable condition includes a voltage converter for converting electrical energy from an initial voltage to a final voltage, and a defibrillator electrically coupled between the converter and the patient and having an energy reservoir for receiving the electrical energy. The defibrillator produces preshaped electrical pulses such as defibrillation pulses and cardioversion pulses. The apparatus additionally includes an energy delivery controller electrically coupled to the patient and the converter and the defibrillator. The controller causes the converter to provide the electrical energy to the defibrillator at a specific charging rate in response to an energy level in the reservoir. The apparatus may include a plurality of electrodes interposed between the defibrillator and the patient and each electrode preferably has an impedance reducing means contained therein. One embodiment of the apparatus may include a H-bridge to produce a positive-going pulse segment and the negative-going pulse segment within the biphasic exponential signals. The apparatus periodically measures the energy as it is being delivered to the patient and can pre-emptively stop or truncate the pulse in the event an error condition is detected, such as an overvoltage condition or if the energy level approaches a predetermined level. The electrical components which store and release the energy minimize the size and expense of the apparatus, while isolating the microcomputer from the high energy levels as the therapeutic pulse is delivered.

Claims

1. A patient-worn energy delivery apparatus for imparting electrical therapy to the body of a patient responsive to an occurrence of a treatable condition, the apparatus comprising:

a. a voltage converter for converting electrical energy from an initial voltage to a final voltage;

b. a defibrillator adapted to be electrically coupled between the converter and the patient, the defibrillator having an energy reservoir for receiving the electrical energy from the converter, the defibrillator producing preshaped electrical pulses therefrom;

c. an energy delivery controller adapted to be electrically coupled to the patient and the converter and the defibrillator, the controller causing the converter to provide the electrical energy to the defibrillator, the controller causing the defibrillator to apply a selectable portion of the electrical energy to the body of the patient, responsive to the occurrence of the treatable condition; and

d. means for measuring the electrical energy as it is being delivered to the body of the patient.

2. The apparatus of claim 1 wherein the energy reservoir includes a plurality of capacitors, the plurality of capacitors being adapted to charge substantially in parallel and discharge substantially in series.

3. The apparatus of claim 2 further comprising a plurality of silicon controller rectifiers and a plurality of opto-triacs, wherein selected ones of the plurality of capacitors are serially connected with selected others of the plurality of capacitors, respective ones of the plurality of silicon controlled rectifiers are serially interposed between adjacent ones of said selected ones and others, and each of the plurality of silicon controlled rectifiers being controllable with a respective one of the plurality of opto-triacs, the plurality of opto-triacs causing the silicon controlled rectifiers to conduct responsive to a therapy initiation command from the controller.

4. The apparatus of claim 2 wherein the selectable portion is determined by the controller using a voltage across the reservoir and a pulse current.

5. The apparatus of claim 1 wherein the preshaped electrical pulses are approximately exponentially-shaped pulses.

6. The apparatus of claim 5 wherein the preshaped electrical pulses are monophasic exponential pulses.

7. The apparatus of claim 5 wherein the preshaped electrical pulses are biphasic exponential pulses.

8. The apparatus of claim 7 wherein each of the biphasic exponential pulses has a positive-going pulse segment and a negative-going pulse segment and a selected amount of the electrical energy is applied to the patient during the positive-going pulse segment and a remaining amount of the electrical energy is applied to the patient during the negative-going pulse segment.

9. The apparatus of claim 8 further comprising a H-bridge to produce the positive-going pulse segment and the negative-going pulse segment of each of the biphasic exponential signals.

10. The apparatus of claim 8 wherein the selected amount of electrical energy is about 60% and the remaining amount of electrical energy is about 40%.

11. The apparatus of claim 1 wherein the selectable portion is determined by the controller using a voltage across the reservoir and a voltage across the patient and a pulse current.

12. The apparatus of claim 11 wherein the selectable portion is further determined by the controller using a minimum energy delivery period and a maximum energy delivery period.

13. The apparatus of claim 1 wherein the defibrillator further comprises at least one insulated gate bipolar transistor for connecting the electrical energy through the patient responsive to the controller, said transistor being enabled before the controller causes the defibrillator to supply the selectable portion of the electrical energy to the patient.

14. The apparatus of claim 1 wherein the converter includes an inductive-boost generator having a first stage having a first stage output voltage and a second stage having a second stage output voltage.

15. The apparatus of claim 14 wherein the first stage output voltage is regulated independently of the second stage output voltage.

16. The apparatus of claim 14 wherein the first stage output voltage is equal to or less than about 40 volts, and the second stage output voltage is equal to or less than about 410 volts.

17. The apparatus of claim 14 wherein at least one of the controller and the converter is shut down responsive to an overvoltage condition in at least one of the first stage voltage output and the second stage voltage output.

18. The apparatus of claim 1 wherein the converter has a first stage with a first stage output voltage level and a second stage with a second stage output voltage level;

wherein the converter converts the energy at a plurality of charging rates such that each of the plurality of charging rates corresponds with a respective one of a plurality of duty cycles, each of the plurality of duty cycles corresponding to a selected output voltage level; and

wherein the plurality of duty cycles includes three duty cycles, the first duty cycle being about 9% when the first stage output voltage level is less than about 20 volts, the second duty cycle being about 42% when the first stage output voltage level is equal or greater than about 20 volts and the second stage output voltage level is less than about 35 volts, and the third duty cycle is about 69% when the second stage output is equal to or greater than about 135 volts.

19. The apparatus of claim 1, further comprising a plurality of electrodes interposed between the defibrillator and the patient, the plurality of electrodes having a conductive surface adapted for placement adjacent the patient'"'"'s skin and having an impedance reducing means contained therein for reducing the impedance between the plurality of electrodes and the patient'"'"'s skin, the impedance reducing means being activated responsive to the occurrence of the treatable condition.

20. The apparatus of claim 19 further comprising:

a. a source of electrical energy at a first voltage; and

b. a carrier means in the form of an upper body harness or garment to be worn by the patient, the carrier means holding the plurality of electrodes therein.

21. The apparatus of claim 1 wherein the converter includes an inductive-boost generator having an output voltage level.

22. The apparatus of claim 1 wherein said measuring means comprises a pulse voltage monitor and a pulse current monitor.

23. The apparatus of claim 22 further comprising means for storing the measured pulse voltage and pulse current.

24. The apparatus of claim 1 wherein said measuring means comprises a pulse voltage monitor, a pulse current monitor and a timer for measuring the pulse voltage and the pulse current over a predetermined time period.

25. The apparatus of claim 24 further comprising means for truncating the electrical energy being delivered to the body of a patient when the electrical energy delivered to the body of the patient is substantially equal to a predetermined maximum energy level.

26. The apparatus of claim 25 wherein the pulse voltage and pulse current are measured approximately every 94 microseconds.

27. The apparatus of claim 25 wherein the predetermined maximum energy level is approximately 360 joules.

28. The electrical circuit of claim 27 wherein said energy reservoir further comprises:

i) a plurality of capacitors being adapted to charge substantially in parallel and discharge substantially in series, said capacitors thereby delivering electrical energy at a second voltage;

ii) a plurality of silicon controller rectifiers and a plurality of opto-triacs, wherein selected ones of the plurality of capacitors are serially connected with selected others of the plurality of capacitors, respective ones of the plurality of silicon controlled rectifiers are serially interposed between adjacent ones of said selected ones and others, and each of the plurality of silicon controlled rectifiers being controllable with a respective one of the plurality of silicon controlled rectifiers being controllable with a respective one of the plurality of opto-triacs, the plurality of opto-triacs causing the silicon controlled rectifiers to conduct responsive to a therapy initiation command from the patient-worn energy delivery apparatus; and

iii) at least one insulated gate polar transistor for connecting the electrical energy through the patient response to the patient-worn energy delivery apparatus, said transistor being enable before patient-worn energy delivery apparatus causes the electrical energy to be applied to the patient.

29. An electrical circuit for a patient-worn energy delivery apparatus for imparting electrical therapy in preshaped electrical pulses to the body of a patient, the circuit comprising:

a. means for supplying electrical energy at a first voltage;

b. an energy reservoir for receiving the electrical energy at the first voltage, the energy reservoir further comprising;

i) a first plurality of dividers connected in series;

ii) a second plurality of diodes connected in series, said second plurality of diodes being alternately connected in series with a plurality of capacitors, wherein said first and second plurality of diodes are connected in parallel such that said capacitors are charged substantially in parallel so as to charge the energy reservoir to a second voltage;

c. an energy delivery controller adapted to be electrically coupled to the patient, the controller causing the patient-worn energy delivery apparatus to apply a selectable portion of the electrical energy at the second voltage to the body of the patient.

30. The electrical circuit of claim 29 wherein the preshaped electrical pulses are approximately exponentially-shaped pulses.

31. The electrical circuit of claim 30 wherein the preshaped electrical pulses are monophasic exponential pulses.

32. The electrical circuit of claim 30 wherein the preshaped electrical pulses are biphasic exponential pulses.

33. The electrical circuit of claim 32 wherein each of the biphasic exponential pulses has a positive-going pulse segment and a negative-going pulse segment and a selected amount of the electrical energy is applied to the patient during the positive-going pulse segment and a remaining amount of the electrical energy is applied to the patient during the negative-going pulse segment.

34. The electrical circuit of claim 33 further comprising a H-bridge to produce the positive-going pulse segment and the negative-going pulse segment of each of the biphasic exponential signals.

35. The electrical circuit of claim 33 wherein the selected amount of electrical energy is about 60% and the remaining amount of electrical energy is about 40%.

36. The electrical of claim 29 wherein the selectable portion is determined by the controller using a voltage across the reservoir and a voltage across the patient and a pulse current.

37. The electrical circuit of claim 36 wherein the selectable portion is further determined by the controller using a minimum energy delivery period and a maximum energy delivery period.

38. The electrical circuit of claim 29 wherein said means for supplying electrical energy at the first voltage comprises a voltage converter for converting electrical energy from an initial voltage to a final voltage, the converter converting the energy at a plurality of charging rates, and including an inductive-boost generator having a first stage having a first stage output voltage and a second stage having a second stage output voltage.

39. The electrical circuit of claim 38 wherein the first stage output voltage is regulated independently of the second stage output voltage.

40. The electrical circuit of claim 38 wherein the first stage output voltage is equal to or less than about 40 volts, and the second stage output voltage is equal to or less than about 410 volts.

41. The electrical circuit of claim 38 wherein at least one of the controller and the converter is shut down responsive to an overvoltage condition in at least one of the first stage voltage output and the second stage voltage output.

42. The electrical circuit of claim 29 wherein said means for supplying electrical energy at the first voltage comprises a voltage converter for converting electrical energy from an initial voltage to a final voltage, the converter converting the energy at a plurality of charging rates, the converter including an inductive-boost generator having a first stage with a first stage output voltage level and a second stage with a second stage output voltage level;

wherein each of the plurality of charging rates corresponds with a respective one of a plurality of duty cycles, each of the plurality of duty cycles corresponding to a selected output voltage level; and

wherein the plurality of duty cycles includes three duty cycles, the first duty cycle being about 9% when the first stage output voltage level is less than about 20 volts, the second duty cycle being about 42% when the first stage output voltage level is equal to or greater than about 20 volts and the second stage output voltage level is less than about 35 volts, and the third duty cycle is about 69% when the second stage output is equal to or greater than about 135 volts.

43. The electrical circuit of claim 29 wherein said means for supplying electrical energy at a first voltage comprises a voltage converter converting electrical energy from an initial voltage to a final voltage at a plurality of charging rates, the converter including an inductive-boost generator having a first stage with a first stage voltage output, and a second stage with a second stage voltage output, the controller causing the patient-worn energy delivery apparatus to apply the selectable portion of the electric energy to the body of the patient, the selectable portion being determined by a voltage across selected ones of the plurality of capacitors and a pulse current.

44. The electrical circuit of claim 43 wherein the preshaped electrical pulses are monophasic exponential pulses.

45. The electrical circuit of claim 43 wherein the preshaped electrical pulses are biphasic exponential pulses.

46. The electrical circuit of claim 45 wherein each of the biphasic exponential pulses has a positive-going pulse segment and a negative-going pulse segment, a selected amount of the electrical energy being applied to the patient during the positive-going pulse segment and a remaining amount of the electrical energy being applied to the patient during the negative-going pulse segment.

47. The electrical circuit of claim 46 further comprising a H-bridge to produce the positive-going pulse segment and the negative-going pulse segment of each of the biphasic exponential signals.

48. The electrical circuit of claim 46 wherein the selected amount of electrical energy is about 60% and the remaining amount of electrical energy is about 40%.

49. The electrical circuit of claim 43 wherein at least one of the controller and the converter is shut down responsive to an overvoltage condition in at least one of the first stage voltage output and the second stage voltage output.

50. A patient-worn energy delivery apparatus for imparting electrical therapy to the body of a patient responsive to an occurrence of a treatable condition, the apparatus comprising

a. a voltage converter for converting electrical energy from an initial voltage to a final voltage;

b. a defibrillator adapted to be electrically coupled between the converter and the patient, the defibrillator having an energy reservoir for reciving the electrical energy from the converter, the defibrillator producing preshaped electrical pulses therefrom;

c. an energy delivery controller adapted to be electrically coupled to the patient and the converter and the defibrillator, the controller causing the converter to provide the electrical energy to the defibrillator, the controller causing the defibrillator to apply a selectable portion of the electrical energy to the body of the patient, responsive to the occurrence of the treatable condition; and

d. means for truncating the delivery of the electrical energy in the event of a detected fault condition.

51. The apparatus of claim 50 further comprising means for measuring the electrical energy as it is being delivered to the body of the patient, wherein said truncating means receives as an input the measured electrical energy.

52. The apparatus of claim 51 wherein said measuring means comprises a pulse voltage monitor and a pulse current monitor.

53. The apparatus of claim 51 wherein said measuring means comprises a pulse voltage monitor, a pulse current monitor and a timer for periodically measuring the pulse voltage and pulse current.

54. The apparatus of claim 53 further comprises means for calculating an energy level delivered to the body of the patient based upon the pulse voltage and the pulse current.

55. The apparatus of claim 54 wherein the programmable logic device truncates the delivery of the electrical energy to the body of the patient when the energy level is generally equal to a predetermined maximum energy level.

56. The apparatus of claim 55 wherein the predetermined maximum energy level is 360 joules.

57. The apparatus of claim 50 wherein the energy reservoir includes a plurality of capacitors, the plurality of capacitors being adapted to charge substantially in parallel and discharge substantially in series.

58. The apparatus of claim 57 further comprising a plurality of silicon controller rectifiers and a plurality of opto-triacs, wherein selected ones of the plurality of capacitors are serially connected with selected others of the plurality of capacitors, respective ones of the plurality of silicon controlled rectifiers are serially interposed between adjacent ones of said selected ones and others, and each of the plurality of silicon controlled rectifiers being controllable with a respective one of the plurality of opto-triacs, the plurality of opto-triacs causing the silicon controlled rectifiers to conduct responsive to a therapy initiation command from the controller.

59. The apparatus of claim 57 wherein the selectable portion is determined by the controller using a voltage across the reservoir and a pulse current.

60. The apparatus of claim 50 wherein the preshaped electrical pulses are approximately exponentially-shaped pulses.

61. The apparatus of claim 60 wherein the preshaped electrical pulses are monophasic exponential pulses.

62. The apparatus of claim 60 wherein the preshaped electrical pulses are biphasic exponential pulses.

63. The apparatus of claim 62 wherein each of the biphasic exponential pulses has a positive-going pulse segment and a negative-going pulse segment and a selected amount of the electrical energy is applied to the patient during the positive-going pulse segment and a remaining amount of the electrical energy is applied to the patient during the negative-going pulse segment.

64. The apparatus of claim 63 further comprising a H-bridge to produce the positive-going pulse segment and the negative-going pulse segment of each of the biphasic exponential signals.

65. The apparatus of claim 63 wherein the selected amount of electrical energy is about 60% and the remaining amount of electrical energy is about 40%.

66. The apparatus of claim 50 wherein the selectable portion is determined by the controller using a voltage across the reservoir and a voltage across the patient and a pulse current.

67. The apparatus of claim 66 wherein the selectable portion is further determined by the controller using a minimum energy delivery period and a maximum energy delivery period.

68. The apparatus of claim 50 wherein each of the plurality of charging rates corresponds with a respective one of a plurality of duty cycles, each of the plurality of duty cycles corresponding to a selected output voltage level.

69. The apparatus of claim 50 wherein the defibrillator further comprises at least one insulated gate bipolar transistor for connecting the electrical energy through the patient responsive to the controller, said transistor being enabled before the controller causes the defibrillator to supply the selectable portion of the electrical energy to the patient.

70. The apparatus of claim 50 wherein the converter includes an inductive-boost generator having a first stage having a first stage output voltage and a second stage having a second stage output voltage.

71. The apparatus of claim 70 wherein the first stage output voltage is regulated independently of the second stage output voltage.

72. The apparatus of claim 70 wherein the first stage output voltage is equal to or less than about 40 volts, and the second stage output voltage is equal to or less than about 410 volts.

73. The apparatus of claim 70 wherein at least one of the controller and the converter is shut down responsive to an overvoltage condition in at least one of the first stage voltage output and the second stage voltage output.

74. The apparatus of claim 50 wherein the converter includes an inductive-boost generator having a first stage with a first stage output voltage level and a second stage with a second stage output voltage level;

wherein each of the plurality of charging rates corresponds with a respective one of a plurality of duty cycles, each of the plurality of duty cycles corresponding to a selected output voltage level; and

wherein the plurality of duty cycles includes three duty cycles, the first duty cycle being about 9% when the first stage output voltage level is less than about 20 volts, the second duty cycle being about 42% when the first stage output voltage level is equal to or greater than about 20 volts and the second stage output voltage level is less than about 35 volts, and the third duty cycle is about 69% when the second stage output is equal to or greater than about 135 volts.

75. The apparatus of claim 50 further comprising a plurality of electrodes interposed between the defibrillator and the patient, the plurality of electrodes having a conductive surface adapted for placement adjacent the patient'"'"'s skin and having an impedance reducing means contained therein for reducing the impedance between the plurality of electrodes and the patient'"'"'s skin, the impedance reducing means being activated responsive to the occurrence of the treatable condition.

76. The apparatus of claim 75 further comprising:

a. a source of electrical energy at a first voltage; and

b. a carrier means in the form of an upper body harness or garment to be worn by the patient, the carrier means holding the plurality of electrodes therein.