Survivalink Corporation

Cardiac Science Corporation

Gary B Stendahl

James E Brewer

Kenneth F Olson

Michael D Welsch

Nora J Utke

John F Stolte

Byron L Gilman

Michael A Tvedt

An apparatus and method for determining an optimal transchest external defibrillation waveform that provides for variable energy in the first or second phase of a biphasic waveform that, when applied through a plurality of electrodes positioned on a patient's torso, will produce a desired response in the patient's cardiac cell membranes. The method includes the steps of providing a quantitative model of a defibrillator circuit for producing external defibrillation waveforms, the quantitative model of a patient includes a chest component, a heart component, a cell membrane component and a quantitative description of the desired cardiac membrane response function. Finally, a quantitative description of a transchest external defibrillation waveform that will produce the desired cardiac membrane response function is computed. The computation is made as a function of the desired cardiac membrane response function, the patient model and the defibrillator circuit model.

Method and apparatus for delivering a biphasic defibrillation pulse with variable energy

A method for determining an optimal transchest external defibrillation waveform which, when applied through a plurality of electrodes positioned on a patient's torso will produce a desired response in the patient's cardiac cell membranes. The method includes the steps of providing a quantitative model of a defibrillator circuit for producing external defibrillation waveforms, the quantitative model of a patient includes a chest component, a heart component, a cell membrane component and a quantitative description of the desired cardiac membrane response function. Finally, a quantitative description of a transchest external defibrillation waveform that will produce the desired cardiac membrane response function is computed. The computation is made as a function of the desired cardiac membrane response function, the patient model and the defibrillator circuit model.

Method and apparatus for determining the second phase of defibrillator devices

A lid open detection circuit for powering ON an automated external defibrillator having a housing and an openable lid formed in the housing, generally incorporates a switch that has a first state for powering ON the AED when the openable lid is open and a second state for powering OFF the AED when the openable lid is closed. The switch is preferably a Hall effect switch.

Lid open detection circuit for automated external defibrillators

A defibrillator battery pack comprises a housing having a first set of battery cells having an upper set and a lower set of cells and a second set of battery cells connected in parallel with one of the upper or the lower sets of the first set of battery cells. The first set of battery cells is used for charging a capacitor bank of a defibrillator. The second set of battery cells cannot be used for charging and is only used for developing a nominal 5 volts to drive a microprocessor and other circuitry components of an electrical control system of the defibrillator. This arrangement increases the life of the battery pack in the lower voltage range, which is advantageous for operating the microprocessor. This arrangement also maintains the intelligence of the electrical control system because the battery cells supplying power to the microprocessor will always fail after, and not before, failure of the battery cells supplying power for charging the capacitor bank.

Defibrillator battery with dual cell stack configuration

An apparatus for generating a waveform for use in externally defibrillating the heart of a patient includes a plurality of capacitors chargeable to respective charge potentials. A control apparatus is operatively coupled with the capacitors to sequentially interconnect the capacitors in a circuit with one another to generate the waveform. Structure including e.g. electrodes is operatively coupled with the capacitors and the control apparatus to apply the waveform to the chest of the patient. The waveform preferably includes an emulated first-phase substantially sinusoidally shaped pulse component having a first polarity. According to biphasic embodiments, the waveform also includes an emulated second-phase substantially sinusoidally shaped pulse component having a second polarity. The control apparatus preferably is constructed to truncate the emulated first-phase pulse component at a predetermined time, preferably based on a design rule used to calculate pulse duration. The design rule calculates the pulse duration to correspond to substantially the peak response of the patient's heart-cell membrane to the first-phase pulse component. Corresponding method embodiments provide additional advantages.

Stacked capacitor truncated damped sinusoidal defibrillation waveform

Method for determining the second phase of external defibrillator devices

The audible alarm system of the present invention incorporates an alarm condition indicator that is designed to detect an alarm condition within the AED. The audible alarm system further incorporates an audible alarm circuit that is connected to the alarm condition indicator and is designed to produce an audible alarm. The audible alarm circuit is initially activated by the alarm condition indicator and then operates independently of the alarm condition after the initial activation.

Audible alarm system for an automated external defibrillator

A fast insulated gate bipolar transistor (IGBT) driver circuit for trunking waveforms in external defibrillators is provided. An input circuit is provided to receive input signals. An isolation transformer is provided to isolate the output from the input. A biasing circuit is connected to the isolation transformer for biasing the IGBT. In response to the biasing circuitry, the IGBT rapidly switches between operational states to truncate waveforms at any point during the delivery of energy to a patient.

Fast isolated IGBT driver for high voltage switching circuitry

A method and apparatus for delivering a stepped truncated damped sinusoidal external defibrillation waveform which, when applied through a plurality of electrodes positioned on a patient's torso will produce a desired response in the patient's cardiac cell membranes is provided. Further, the method and apparatus sufficiently approximates a constant current defibrillation shock pulse. The method includes the steps monitoring a patient-dependent electrical parameter and determining a duration based on the parameter determined. First and second charge storage components are then charged. A first truncating switch is then closed to discharge the first charge storage component. After a predetermined delay, a second truncating switch is closed to discharge the second charge storage component. Then, after the duration period that was calculated has expired the switches are opened to truncate the waveform. The computation of discharge duration is made as a function of the desired cardiac membrane response function, a patient model and a defibrillator circuit model.

Stepped truncated damped sinusoidal defibrillation waveform

A method and apparatus for delivering a truncated damped sinusoidal external defibrillation waveform which, when applied through a plurality of electrodes positioned on a patient's torso will produce a desired response in the patient's cardiac cell membranes is provided. The method includes the steps monitoring a patient-dependent electrical parameter and determining a duration based on the parameter determined. A first set of charge storage capacitors is then charged. A first truncating switch is then closed to discharge the first set of capacitors. Then, after the duration period that was calculated has expired the switch is opened to truncate the waveform. The computation of discharge duration is made as a function of the desired cardiac membrane response function, a patient model and a defibrillator circuit model.

Single capacitor truncated damped sinusoidal defibrillation waveform

The AED of the present invention has a housing and a removable power supply, contained within its own power supply case, that is connected to a circuit for generating a defibrillation pulse. The circuit is electrically connectale to a pair of electrodes for delivering the defibrillation pulse. the AED further includes a temperature sensing device that is mounted inside the power supply case and connected to the power supply. The temperature sensing device senses the temperature in the power supply case and enables the adjustment of the operating parameters of the AED according to the sensed temperature.

Automated external defibrillator with the ability to sense temperature

Apparatus and method for selecting from a pair of capacitor banks for delivery of positive and negative polarity portions of a biphasic defibrillator pulse with a selector switch circuit for each capacitor bank, the circuit including a solid state phase selector switch preferably made up of a series connected plurality of IGBT's and each phase selector switch having a phase selector driver and select phase control for turning the phase selector switch ON and OFF when desired to start and truncate selected portions of the biphasic defibrillation pulse.

High voltage phase selector switch for external defibrillators

Apparatus and method for parallel charging of mixed capacitors, including a source for generating a train of high frequency pulses coupled through a pulse transformer, a high speed diode connected to the pulse transformer, a filter capacitor connected to the high speed diode and acting as a low-pass filter for the train of pulses, and a plurality of solid state switches for selectively coupling and decoupling the voltage across the filter capacitor to one of a plurality of capacitor banks which make up the biphasic high voltage defibrillation pulse supply.

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Crystal, MN, United States of America

Gary B Stendahl