Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method of generating and applying a defibrillation shock of the present invention includes first applying a defibrillation shock pulse to a patient with an initial predetermined amount of energy not based on a patient-dependent electrical parameter, and while monitoring a patient-dependent electrical parameter. Next, patient transthoracic impedance is determined based on the patient-dependent electrical parameter. Finally, a subsequent predetermined amount of energy is applied to the patient based on the patient transthoracic impedance calculated above and while monitoring the patient-dependent electrical parameter. Subsequent defibrillation shock pulses are applied using a patient impedance based on the patient-dependent electrical parameter observed during the most recent defibrillation shock. In this manner, an optimal combination of charged voltage and the maximum allowed current (under the AAMI defibrillation waveform standard) is applied for a patient's given transthoracic impedance.

Abstract: An automated external defibrillator automatically performs periodic self-tests on a daily and weekly basis. Self-test failures are identified by a watchdog timer which is reset upon activation of each periodic self-test. If the watchdog timer times out a maintenance indication is activated. The timeout period of the watchdog timer is non-repeating and non-periodic (typically 30 hrs.). Tested functions include the presence and interconnection of defibrillator electrodes, battery charge state, and the operability of the high voltage circuit. Visual and audible indicators are actuated to alert an operator if faults are identified. A record of each self-test is stored in memory, and can be subsequently retrieved through a communications port.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 external defibrillator is utilized for applying a damped sinusoidal waveform having a first waveform phase and a second waveform phase to a pair of electrodes. The external defibrillator has a first capacitive component, a first inductive component, a first truncating switch, and waveform control circuitry. The waveform control circuitry of the defibrillator controls the first and second truncating switches such that the duration of the second phase waveform delivered by the second charge storage component is greater than the duration of the first phase waveform delivered by the first charge storage component.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An AED includes a housing. Electronic circuitry is disposed in the housing for delivery of an electric shock to a stricken patient. A removable battery pack is selectively, operably, communicatively coupled to the electronic circuitry. The battery pack has an anticipatory detector for generating an anticipatory signal to the electronic circuitry. The signal indicates to the electronic circuitry that the disengagement of the battery pack from the AED is imminent. The present invention further includes a method for ensuring that the high voltage storage circuits of the AED are safely discharged prior to disengaging the battery pack from the AED.

Abstract: The invention provides a sealed package system for housing at least one medical electrode apparatus and for enabling the periodic testing thereof, comprising a thin, generally flat flexible envelope constructed and arranged to form an interior cavity for enclosing a conductive gel contact surface of an electrode apparatus, the envelope having at least one continuous layer of a homogeneous, non-conductive, polymeric material, the envelope further having first and second sides; and a structure for conducting current across the envelope to the interior cavity, the conductive structure being electrically connectible to the electrode conductive contact surface.

Abstract: A circuit detectable arrangement of electrodes and a package thereof are provided so that the presence of a fresh package of electrodes can be detected by a device and can be distinguished from electrodes that have been used or tampered with. A first electrode is disposed on an electrically non-conductive liner, a second electrode is disposed on an electrically non-conductive liner, and an electrical connector is provided between the first and second electrodes for electrically completing a circuit connecting the lead wire of the first electrode to the lead wire of the second electrode. An electrode package is also provided including the first and second electrodes therein. Within the package, the first and second electrodes are provided adjacent to one another with their backing layers generally parallel to one another and with a loop formed in the electrical connector.

Abstract: An automated external defibrillator which automatically performs self-tests on a daily and weekly basis. Tested functions include the presence and interconnection of defibrillator electrodes, battery charge state and the operability of the high voltage circuit. Visual and audible indicators are actuated to alert an operator if faults are identified. A record of each self-test is stored in memory, and can be subsequently retrieved through a communications port.

Abstract: A portable automated external defibrillator (AED) configured for use with a packaged pair of defibrillator electrodes of the type electrically coupled to one another within the package and having lead wires extending from the package and an electrical connector on the ends of the lead wires. The AED includes a case with an electrode compartment configured to hold the packaged electrodes, and an openable lid for enclosing the compartment. Electrode terminals configured for electrical interconnection to the electrical connector of the electrodes, a speaker and an LED display are positioned within the electrode compartment. An operator-actuated rescue switch and a rescue LED display are positioned on the outside of the case. A high voltage circuit generates defibrillation pulses and applies the pulses to the electrode terminals. The operation of the AED is controlled by a digital control system. Rescue mode operation of the AED is initiated when the lid is opened.