Full-tilt exponential defibrillation waveform

• US 6,539,255 B1
• Filed: 07/16/1999
• Issued: 03/25/2003
• Est. Priority Date: 07/16/1998
• Status: Expired due to Fees

• Current Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Original Assignee: Cardiac Science Operating Company (Cardica Incorporated)
• Inventors: Tchou, Patrick J., Brewer, James E.
• Primary Examiner(s): EVANISKO, GEORGE ROBERT
• Application Number:
  US09/354,300
• Time in Patent Office: 1,348 Days
• Field of Search: 607/5, 607/72, 607/74, 607/7, 607/8
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3906 characterised by the form of the shockwave
• CPC Class Codes: A61N 1/3912 Output circuitry therefor, e.g. switches

Abstract

The characteristics of a full-tilt exponential waveform are developed through use of a charge burping model or through use of a transthoracic cell response model. These characteristics are implemented within a pulse delivery circuit, which itself is implemented within an internal defibrillator or within an external defibrillator. The pulse delivery circuit includes at least one switch which starts and stops the delivery of the defibrillation pulse. Delivery of the defibrillation pulse is started by the switch when there is sufficient stored energy to deliver a desired pulse. Delivery of the defibrillation pulse is stopped by the switch when the current flowing through the switch is substantially zero and the exponential waveform of the pulse is substantially fully decayed.

Claims

1. A defibrillator comprising:

an energy source;

a capacitor system operably coupled to said energy source via a charging system;

the charging system being adapted for storing electrical energy in said capacitor system;

a monitoring circuit for monitoring the voltage on said capacitor system;

a selector switch circuit coupled to said monitoring circuit;

a processor and control logic circuit; and

an electrode operably coupled to said capacitor system via said selector switch circuit wherein said capacitor system delivers an electrical pulse from said electrical energy stored in said capacitor system to said electrode in a full-tilt exponential defibrillation waveform controlled by the processor and control logic circuit, wherein said full-tilt exponential defibrillation waveform is truncated by the switching of said selector switch circuit at about ninety five percent of the full waveform of said electrical pulse at the same time a current flowing through said selector switch circuit is approximately zero amps wherein said zero amps is indicated by said monitoring circuit when said monitored voltage on said capacitor system is approximately zero, and wherein said full-tilt exponential waveform has delivered about ninety nine and seventy five one hundredths percent of the electrical energy of said electrical pulse at the time of truncation.

2. The defibrillator of claim 1, wherein said defibrillator is selected from a group consisting of an internal defibrillator and an external defibrillator.

3. The defibrillator of claim 1, wherein said electrical pulse is of the type of pulse selected from a group consisting of monophasic and biphasic pulse.

4. The defibrillator of claim 1, further comprising a sensor system wherein a characteristic of said electrical pulse is determined by said sensor system.

5. A defibrillator comprising:

means for providing energy;

means for storing energy operably coupled to said means for providing energy;

means for processing and controlling the providing, storing and delivery of energy;

means for monitoring the voltage of said stored energy;

means for switching coupled to said means for monitoring; and

means for delivering an electrical pulse operably coupled, via said means for switching, to said means for storing energy, wherein said means for storing energy is also for releasing the stored-energy as said electrical pulse to said means for delivering in a full-tilt exponential defibrillation waveform wherein said full-tilt exponential defibrillation waveform is truncated by said means for switching at about ninety five percent of the full waveform of said electrical pulse at the same time a current flowing through said means for switching is approximately zero amps wherein said zero amps indicating that is indicated by the means for monitoring when said monitored voltage on said means for storing energy is approximately zero, and wherein said full-tilt exponential waveform has delivered about ninety nine and seventy five one hundredths percent of the electrical energy of said electrical pulse at the time of truncation.

6. The defibrillator of claim 5, wherein said defibrillator is selected from a group consisting of an internal defibrillator and an external defibrillator.

7. The defibrillator of claim 5, wherein said electrical pulse is of the type of pulse selected from a group consisting of a monophasic and a biphasic pulse.

8. The defibrillator of claim 5, further comprising a sensor system wherein a characteristic of said electrical pulse is determined by said sensor system.

9. A method of delivering a defibrillation pulse, comprising the steps of:

generating electrical energy;

storing said electrical energy;

releasing at least a first portion of said stored electrical energy via a selector switch circuit in a pulse having a positive polarity exponentially decaying defibrillation waveform;

monitoring the voltage of the stored electrical energy and stopping the release of said stored electrical energy upon a current in said selector switch reaching substantially zero amps when said monitored voltage of said stored electrical energy is approximately zero, resulting in said full-tilt exponential defibrillation waveform being truncated at about ninety five percent of the full waveform of said electrical pulse and in said full-tilt exponential defibrillation waveform delivering about ninety nine and seventy five one hundredths percent of the electrical energy of said electrical pulse at the time of truncation.

10. The method of claim 9, wherein said pulse is selected from a group consisting of a monophasic pulse and a first phase of a biphasic pulse.

11. The method of claim 9, further comprising the steps of releasing at least a second portion of said stored electrical energy in a pulse having a negative polarity exponentially decaying waveform and stopping the release of said electrical energy upon a current component of said electrical energy reaching substantially zero amps.

12. The method of claim 9, wherein said pulse is delivered by a defibrillator selected from a group consisting of an internal defibrillator and an external defibrillator.