Abstract: The present invention provides a portable defibrillator having a capacitor adapted to receive an electrical charge to deliver a defibrillation charge. Power terminals are provided to receive line power. A charging circuit is provided to charge the capacitor from line power after the power terminals receive line power. Therefore, the defibrillator is capable of receiving line power, such as standard 120 VAC, to charge the defibrillator's capacitor. By charging the capacitor directly through line power, the capacitor is charged in much less time than searching for and replacing a defibrillator battery.

Abstract: Defibrillator assemblies and methods to wirelessly transfer energy from an external source to a battery or other rechargeable power source within the defibrillator assembly. The transfer of energy may be through a non-contact interface on a defibrillator cradle or a docking station that mounts the defibrillator. The rate of energy transfer may be equal to the energy drain caused by self-discharge and automated self-testing. Accordingly, since the rate of energy transfer is lower than that required to run the defibrillator system continuously, several wireless methods of energy transfer may be used. In addition, the defibrillator assembly may communicate diagnostic and non-diagnostic data to the external source.

Abstract: A system is provided for delivering a defibrillation pulse to a patient and a corresponding method of storing such a system is provided in accordance with the present invention. The system includes a defibrillator (e.g., an AED) that is configured to deliver the defibrillation pulse to the patient and a cell that is configured to convert light into electrical power for the defibrillator. The method includes storing an defibrillator of the system for future use and arranging a light receiving system to receive light such that the light receiving system converts light into electrical power for the defibrillator.

Abstract: The presence of a cardiac pulse in a patient is determined by evaluating physiological signals in the patient. In one embodiment, a medical device evaluates two or more different physiological signals, such as phonocardiogram (PCG) signals, electrocardiogram (ECG) signals, patient impedance signals, piezoelectric signals, and accelerometer signals for features indicative of the presence of a cardiac pulse. Using these features, the medical device determines whether a cardiac pulse is present in the patient. The medical device may also be configured to report whether the patient is in a VF, VT, asystole, or PEA condition, in addition to being in a pulseless condition, and prompt different therapies, such as chest compressions, rescue breathing, defibrillation, and PEA-specific electrotherapy, depending on the analysis of the physiological signals. Auto-capture of a cardiac pulse using pacing stimuli is further provided.

Abstract: A method and system for monitoring the capacity of a battery pack is provided. The battery pack is capable of delivering current to a load. The battery pack includes a monitor cell and battery cells. The monitor cell has an initial energy level that is lower by a predetermined difference from the initial energy level of at least one of the other battery cells. A monitoring system including an analog-to-digital converter and a microprocessor is connected to the battery pack and monitors the voltage of the battery pack. When the monitoring system detects a voltage change indicating depletion of the monitor cell, the monitoring system provides a signal indicative that the battery pack is nearing depletion. The proportional rate of discharge of the monitor cell relative to the other cells during normal defibrillator operation is matched to the proportional rate of discharge occurring at other times.

Abstract: A method and apparatus for controlling the common mode impedance misbalance of an isolated single-ended circuit for all common mode paths, thereby allowing the balancing of the common mode impedances which reduces common mode effects while maintaining the advantages of the single-ended amplifier including circuit simplicity and the reference input connected to circuit ground. In one embodiment, two solid shields enclose the circuit as completely as possible with the inner shield connected to circuit ground which is also the reference for all other inputs to the circuit. A discrete capacitor is connected between the outer shield and each of the non-reference inputs. When the shield is complete, i.e., solid, almost solid with minimal holes or a fine mesh, the value of the discrete capacitor is selected to match the parasitic capacitance formed between the outer shield and the inner shield. In another embodiment, the shield may be incomplete, i.e.

Abstract: A method and system for monitoring the capacity of a battery pack (6) is provided. The battery pack (6) is capable of delivering current to a load (R.sub.L). The battery pack (6) includes a monitor cell (C4) and battery cells (C1, C2, and C3). The monitor cell (C4) has a predetermined initial energy level that is lower than the predetermined initial energy level of the battery cells. A monitoring system (22) including an analog-to-digital converter (10) and a microprocessor (12) is connected to the battery pack and monitors the voltage of the battery pack. When the monitoring system detects a voltage change indicating depletion of the monitor cell (C4), the monitoring system provides a signal indicative that the battery pack is nearing depletion.

Abstract: A high energy transfer relay includes a housing, a solenoid, a pivot arm, a stationary contact, a switching contact and a leaf spring. The switching contact is mounted on the leaf spring. The armature of the solenoid is coupled to the pivot arm such that when the solenoid is energized, the pivot arm moves in the direction of the stationary contact. Movement is against the force of the leaf spring which is positioned to bias the pivot arm away from the stationary contact against a stop. The leaf spring also pre-loads the pivot point. In addition, the resilience of the leaf spring cushions the impact of the switching contact on the stationary contact to help prevent contact bounce. The outer end of the pivot arm includes a flat that coacts with a flat wall to form an air cushion. The air cushion also assists in preventing contact bounce by absorbing the momentum of the pivot arm after the contacts mate.

Abstract: In an external cardiac defibrillator (8), a method and system for determining when a relay (22) has failed in a conductive state. The defibrillator (8) includes a charge circuit (14) that charges an energy storage capacitor (C) to a predetermined voltage. The relay (22) is closed to direct a defibrillation pulse from the energy storage capacitor to a patient (25) needing ventricular therapy. The relay (22) is then opened following application of the defibrillation pulse. A monitor circuit (18) monitors the voltage on the energy storage capacitor. If the measured voltage across the energy storage capacitor (C) is less than or equal to a threshold value after a predetermined delay, the relay (22) has failed. If the measured voltage exceeds the threshold value, the relay (22) is operating correctly.

Abstract: A portable defibrillator (10) with a common therapy/data port (12). A set of electrodes (34) is connected to the therapy/data port to connect the defibrillator to a patient. If connected to a patient, the defibrillator operates in a normal mode of operation where it analyzes a patient's electrocardiogram (ECG), and, if required, applies defibrillation therapy through the port to the patient. A communication cable (42) is connected to the therapy/data port to connect the defibrillator to an auxiliary component (44). If connected to an auxiliary component, the defibrillator operates in a data communication mode of operation where data may be transmitted to and received from the auxiliary component through the therapy/data port. A test cable is connected to the therapy/data port to connect the defibrillator to a test load. If connected to a test load, the defibrillator operates in a user test mode of operation to allow a user to test the operation of the defibrillator.

Abstract: Circuits for controlling the current flow of an energy pulse as a function of the temperature of a resistive element in the circuit so that the current flow varies over time in accordance with a predetermined waveform. The circuits include at least one negative temperature coefficient thermistor connected between an energy storage device and connectors for delivering energy stored in the storage source to an external load. In one embodiment of the invention the circuit includes a second thermistor for shunting a residual portion of the current delivered by an energy pulse away from the external load. In another embodiment of the circuit, a small inductive device is used for adjusting the shape of the predetermined waveform. In yet another embodiment of the device, a plurality of thermistors arranged in a bridge-like configuration are used to control the current of the energy pulse so that its waveform is biphasic.

Abstract: Circuits for controlling the current flow of an energy pulse as a function of the temperature of a resistive element in the circuit so that the current flow varies over time in accordance with a predetermined waveform. The circuits include at least one negative temperature coefficient thermistor connected between an energy storage device and connectors for delivering energy stored in the storage source to an external load. In one embodiment of the invention the circuit includes a second thermistor for shunting a residual portion of the current delivered by an energy pulse away from the external load. In another embodiment of the circuit, a small inductive device is used for adjusting the shape of the predetermined waveform. In yet another embodiment of the device, a plurality of thermistors arranged in a bridge-like configuration are used to control the current of the energy pulse so that its waveform is biphasic.

Abstract: An energy transfer circuit (40) for delivering a cardiac defibrillation pulse to a patient (50). An energy storage capacitor (16) is coupled to a pair of electrodes (52a, 52b) through an electronic switch (42). The electronic switch is controlled by a control circuit (20). A current shunt 56 is connected in parallel with a pair of defibrillation electrodes (52a, 52b) to divert a leakage current that flows through the electronic switch away from the patient when a defibrillation pulse is not being delivered. A current sensor (64) or a voltage sensor (72) provide a feedback signal to the control circuit to regulate the energy of the defibrillation pulse that flows through the patient.

Abstract: A sensor for detecting the firing of a spark plug while maintaining electrical isolation of electronic equipment is disclosed. In the preferred embodiment, a conductive element is attached to one electrical lead of a neon bulb. A wrap secures one end of an optical fiber to the neon bulb for collecting the light from the neon bulb. The optical fiber carries the light from the neon bulb to a data logging device. During use, the conductive element is secured to an insulated spark plug wire and, when the spark plug fires, a voltage between the leads of the neon bulb is induced, causing the neon bulb to produce a pulse of light. The light pulse from the neon bulb is carried by the optical fiber and monitored by the data logging device. By providing an optical fiber to link the data logging device to the neon bulb, electrical isolation is accomplished.

Abstract: A portable, interactive medical electronic device exemplified by a defibrillator. The device obtains information about a patient's condition, such as ECG and transthoracic impedance data, directly from the patient, and information pertinent to the treatment of the patient indirectly through an operator of the device, and produces a medically appropriate action such as a defibrillation shock in response. Indirect information is obtained through information processing means that includes means for prompting the operator of the device and means for receiving the operator's responses thereto. Prompts may include both questions and instructions, and in one embodiment the information processing means obtains the assent of the operator before causing the defibrillation shock. Indirect information may include information as to whether the patient is conscious, and as to whether or not cardiopulmonary resuscitation has been performed.

Abstract: A portable, interactive medical electronic device exemplified by a defibrillator. The device obtains information about a patient's condition, such as ECG and transthoracic impedance data, directly from the patient, and information pertinent to the treatment of the patient indirectly through an operator of the device, and produces a medically appropriate action such as a defibrillation shock in response. Indirect information is obtained through information processing means that includes means for prompting the operator of the device and means for receiving the operator's responses thereto. Prompts may include both questions and instructions, and in one embodiment the information processing means obtains the assent of the operator before causing the defibrillation shock. Indirect information may include information as to whether the patient is conscious, and as to whether or not cardiopulmonary resuscitiation has been performed.