Abstract: An energy reduction unit is removably connectable to an external defibrillator to reduce the defibrillation energy delivered by the defibrillator to a patient. Use of the energy reduction unit is particularly suited to defibrillating pediatric patients (infants and children under 8) with an automatic or semi-automatic external defibrillator (AED). In one embodiment, the energy reduction unit includes an attenuator which partially dissipates energy produced by the AED. The attenuator is advantageously designed to present an impedance to the AED which, when connected to the patient, is approximately equal to the patient's impedance. The energy reduction unit may include a presence-detect function which enables the defibrillator to modify analysis of ECG signals to account for differences heart rhythms of pediatric and adult patients. In a second embodiment, the energy reduction unit includes an energy control modifier circuit which affects the charging operations performed internal to the AED.

Abstract: An automatic external defibrillator ("AED") is described that includes a high voltage delivery circuit for producing a biphasic electrical pulse to defibrillate a patient. The delivery circuit includes a plurality of capacitors controlled by IGBTs. The bridge circuit has four SCRs which are selectively switched to produce, for example, a biphasic steering of current.

Abstract: A defibrillator circuit that delivers high voltage electrical pulses and lower energy pacing pulses to a patient. The circuit allows the patient to be isolated so that no current leaks prior to the administration of the pacing or defibrillation pulse. In one embodiment, the delivery circuit includes a high voltage capacitor, with a GTO selectively connecting the positive terminal of the capacitor to ground. The negative terminal of the capacitor is coupled to one terminal of a bridge circuit, and another terminal of the bridge circuit is connected to ground. The bridge circuit has four SCRs which are selectively switched to produce the biphasic steering of current. Current conduction through the bridge circuit is initiated and commutated by the GTO. Turning on the GTO connects the positive terminal of the charged capacitor to ground, thereby lowering the potential of the negative terminal and causing current flow through the bridge circuit.

Abstract: This invention relates to medical electrode systems and, in particular, to a defibrillator electrode system for use with an automatic or semi-automatic external defibrillator (AED). This invention provides a medical electrode system with two electrodes. Each electrode has a flexible substrate with an adhesive surface; a conductor disposed on the substrate; and an electrode disposed on the substrate and electrically connected to the conductor. The electrode pads are each imprinted to show the proper placement of the electrode. Additionally, the medical electrode system may have the electrode pads adhered to a single removable releasing surface. The removable releasing surface may have a fold-line along a center axis between the two electrode pads, or alternatively may have perforations along the center axis. Ideally, the imprinting on each electrode pad can be interpreted by an AED operator without reviewing the imprinting of the other electrode pad.

Abstract: The present invention is an apparatus and method for detecting differential mode signals in an environment where differential mode signals co-exist, and might be corrupted by, common mode signals. The most basic apparatus of the present invention essentially comprises first and second input leads through which both differential mode and common mode signals are input; a first amplifier block having a gain that is substantially one; and at least an inverting node and a non-inverting node connected to the first and second input leads. The output of the amplifier block is fed back to the input of the non-inverting node of the amplifier block in a manner to increase differential mode impedance while maintaining a low common mode impedance. Various embodiments of the basic presently claimed circuitry provides for additional methods of monitoring the level of common-mode signal introduced to the apparatus and other fault detection functions.

Abstract: The present invention is an apparatus and method for detecting differential mode signals in an environment where differential mode signals co-exist, and might be corrupted by, common mode signals. The most basic apparatus of the present invention essentially comprises first and second input leads through which both differential mode and common mode signals are input; a first amplifier block having a gain that is substantially one; and at least an inverting node and a non-inverting node connected to the first and second input leads. The output of the amplifier block is fed back to the input of the non-inverting node of the amplifier block in a manner to increase differential mode impedance while maintaining a low common mode impedance. Various embodiments of the basic presently claimed circuitry provides for additional methods of monitoring the level of common-mode signal introduced to the apparatus and other fault detection functions.