Patient-worn energy delivery apparatus

• US 6,097,982 A
• Filed: 04/03/1998
• Issued: 08/01/2000
• 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: Peduzzi, David J., Glegyak, John A.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US09/054,714
• Time in Patent Office: 851 Days
• Field of Search: 607/5-8
• 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

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. The apparatus includes a voltage converter for converting electrical energy from an initial voltage to a final voltage at a plurality of charging rates, 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.

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 defibrillator producing precharged electrical pulses therefrom, the electrical pulses being one of a defibrillator pulse and cardioversion pulses;

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 in the form of one of the defibrillator pulses and the cardioversion pulses to the body of the patient, responsive to the treatable condition;

d. means for sensing the voltage and current being applied to the body of the patient by the defibrillator;

e. timer for determining a time length of the electrical pulse being applied to the body of the patient; and

f. means for terminating the electrical pulse being delivered to the body of the patient based on a product of the sensed voltage, current and the time length of the electrical pulse.

2. The apparatus of claim 1 wherein the precharged electrical pulses are biphasic exponential-shaped pulses.

3. The apparatus of claim 2 wherein each of the biphasic exponential pulses has a positive-going pulse segment and a negative-going pulse segment and said terminating means terminates the positive-going pulse based on a predetermined energy factor dependent on the sensed voltage and current and the time length and a remaining amount of the electrical energy is applied to the patient during the negative-going pulse segment.

4. The apparatus of claim 1, further comprising means for sensing an electrical impedance between the converter and the patient to determine an operating condition of the defibrillator.

5. 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.

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

7. The apparatus of claim 6 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.

8. The apparatus of claim 7 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;

said H-bridge being further comprised of;

a first plurality of insulated gate bipolar transistors having a first polarity;

a second plurality of insulated gate bipolar transistors having a second polarity;

a transformer having first and second secondary windings for selectively triggering said first and second plurality of insulated gate bipolar transistors;

means for delivering the positive-going pulse segment through said first plurality of insulated gate bipolar transistors; and

means for delivering the negative-going pulse segment through said second plurality of insulated gate bipolar transistors.

9. 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%.

10. The apparatus of claim 5 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.

11. 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.

12. The apparatus of claim 11 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.

13. The apparatus of claim 1 wherein the defibrillator further comprises at least one insulated gate bipolar transistor for conducting the electrical energy through the patient responsive to the controller.

14. The apparatus of claim 1 wherein the voltage converter includes an inductive-boost voltage 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 15 wherein the selectable portion is further determined by the controller using a minimum energy delivery period and a maximum energy delivery period.

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. 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 converting electrical energy from an initial voltage to a final voltage at a plurality of charging rates, the converter including an inductive-boost generator;

b. a defibrillator electrically coupled between the converter and the patient, the defibrillator having a plurality of capacitors being adapted to charge substantially in parallel and discharge substantially in series and the defibrillator producing preshaped electrical pulses, the electrical pulses being approximately exponentially-shaped pulses and the electrical pulses being one of defibrillation pulses and cardioversion pulses;

c. an energy delivery controller 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 in the form of one of the defibrillation pulses and the cardioversion pulses to the body of the patient responsive to the occurrence of the treatable condition, the selectable portion being determined by a voltage across selected ones of the plurality of capacitors and a pulse current;

d. means for sensing the voltage and current being applied to the body of the patient by the defibrillator;

e. timer for determining a time length of the electrical pulse being applied to the body of the patient; and

f. means for terminating the electrical pulse being delivered to the body of the patient based on a product of the sensed voltage, current and the time length of the electrical pulse.

19. The apparatus of claim 18 wherein the controller causing the converter to provide the electrical energy to the defibrillator at selected ones of the plurality of charging rates.

20. The apparatus of claim 18 wherein the preshaped electrical pulses are biphasic exponential pulses, and 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.

21. The apparatus of claim 20 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.

22. The apparatus of claim 18 wherein the defibrillator further comprises a plurality of silicon controlled rectifiers and a plurality of opto-triacs and at least one insulated gate bipolar transistor, 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 and the at least one insulated gate bipolar transistor conducting the electrical energy through the patient responsive to a therapy initiation command from the controller.

23. The apparatus of claim 18 further comprising:

a. 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;

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

c. 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.

24. The apparatus of claim 23 wherein the defibrillator further comprises at least one insulated gate bipolar transistor for conducting the electrical energy through the patient responsive to the controller.