Abstract: A circuit package with improved heat dissipation properties for high-power circuits. In one embodiment, the circuit package comprises two circuit boards positioned in different planes, at least one brace affixed between the two circuit boards, a molded housing enclosing an area between the circuit boards, and a plurality of electrically conductive leads extending from the sides of the circuit package. The molded housing is configured to expose at least one surface of the circuit boards to the exterior surface of the circuit package. The leads are configured in a J-shape, which allows the circuit package to be mounted in an upright position. The brace functions as a flexible spacer for holding the two circuit boards in position during the application of the molded housing. In one embodiment, a H-bridge circuit is configured on the first and second circuit boards of the circuit package.

Abstract: The presence of a cardiac pulse in a patient is determined by evaluating fluctuations in an electrical signal that represents a measurement of the patient's transthoracic impedance. Impedance signal data obtained from the patient is analyzed for a feature indicative of the presence of a cardiac pulse. Whether a cardiac pulse is present in the patient is determined based on the feature in the impedance signal data. Electrocardiogram (ECG) data may also be obtained in time coordination with the impedance signal data. Various applications for the pulse detection of the invention include detection of PEA and prompting PEA-specific therapy, prompting defibrillation therapy and/or CPR, and prompting rescue breathing depending on detection of respiration.

Abstract: A system is described that comprises a medical device on which is installed a version of software and a software agent communicatively coupled to the medical device without regard to the version of software installed on the medical device. An example of the medical device includes a defibrillator. The software agent may reside in a personal digital assistant and can be operated to communicate with the defibrillator to access the data stored in the defibrillator irrespective of the version of software of the defibrillator.

Abstract: The present invention provides a system, method and apparatus for obtaining status information from a portable medical device and communicating said status information to a remote system or user. In one embodiment, the system comprises a sensing device that comprises an optical receiver for receiving status information from at least one status indicator of the portable medical device. The optical receiver is positioned in sufficient proximity to the status indicator to allow optical communication between the optical receiver and the status indicator. A circuit couplable to the optical receiver communicates the status information represented by the status indicator to the remote system or user. In another embodiment, the sensing device comprises a microphone to receive audible status signals from the portable medical device. In yet another embodiment, the sensing device is mounted to a housing, which allows sensing device to sense the status information of an enclosed portable medical device.

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: An energy adjusting circuit for use with a defibrillator. The energy adjusting circuit reduces the defibrillation pulse energy that would otherwise be applied to the patient by the defibrillator. The energy adjusting circuit can be part of the defibrillator itself, or part of an adapter coupled to the output ports of a conventional defibrillator. In an adapter designed for pediatric defibrillation, the adapter may include paddles configured for use on babies and small children. The energy adjusting circuit may be formed entirely from passive components and may include a divider circuit with two resistors. The resistance of the two resistors is selected so as to absorb a predetermined percentage of the defibrillation pulse energy that would otherwise be applied to the patient. An isolation circuit may be further included to assist with the measurement of ECG signals through the electrodes.

Abstract: The invention provides a wireless automatic location identification (ALI) capable system (10), including a medical device (12) having a wireless data communicator (14), a wireless communication network (16), and a remote locating service (18) for remotely locating and monitoring one or more medical devices over the wireless communication network. When the medical device is linked to the remote locating service over the communication network, the ALI-capable system identifies the location of the medical device and relays the location information to the remote locating service. The system permits reliable determination of the location of the medical device wherever the medical device is situated. The medical device may further be configured to transmit signals indicative of its status, condition, or self-test results, to the remote locating service. This feature allows the remote locating service to centrally monitor the status or condition of a plurality of medical devices.

Abstract: A medical device constructed according to the invention includes electrodes (12a, 12b), a measuring unit (24) for measuring a patient-dependent electrical parameter (e.g., impedance) of the patient, an electrotherapy generator (26) for delivering electrotherapy to the patient, and a processing unit (20) for controlling the delivery of electrotherapy to the patient. Electrotherapy is preferably delivered to the patient based on the measured patient-dependent electrical parameter and a predetermined response of a reference patient to a nominal electrotherapy. The actual electrotherapy delivered to the patient is controlled so that the electrotherapy has a probability of success for the patient that is equivalent to the probability of success of the nominal electrotherapy for the reference patient. A consistent shock efficacy across different patients is achieved.

Abstract: An external defibrillator with an output circuit having four legs arrayed in the form of an “H” (an “H-bridge”) is disclosed. The output circuit is designed to be able to conduct a range of defibrillation pulse energies, from below 50 joules to above 200 joules. Each leg of the output circuit contains a solid-state switch. By selectively switching on pairs of switches in the H-bridge, a biphasic defibrillation pulse may be applied to a patient. The switches in three of the legs of the H-bridge output circuit are preferably silicon controlled rectifiers (SCRs). Gate drive circuits are coupled to the SCRs to bias the SCRs with a voltage that allows the SCRs to remain turned-on even when conducting low current. The switch in the fourth leg is preferably a pair of insulated gate bipolar transistors (IGBTs) coupled in series. A gate drive circuit is coupled to the gate of the IGBTs to provide a slow turn-on and a fast turn-off of the IGBTs.

Abstract: A method and apparatus determines the presence of a cardiac pulse in a patient by evaluating a physiological signal in the patient, preferably for the presence of characteristic heart sounds. The presence of a heart sound in a patient is determined by analyzing phonocardiogram (PCG) data obtained from the patient. Analyzing the PCG data may include evaluating temporal energy in the PCG data or evaluating spectral energy in the PCG data. Evaluating temporal energy in the PCG data may include estimating a first and second energy in the PCG data and comparing the first and second energy to determine a relative change in energy between them. Evaluating spectral energy in the PCG data may include calculating an energy spectrum of the PCG data and evaluating either the energy value or the frequency of a peak energy in the energy spectrum. The presence of a heart sound may also be determined by combining an evaluation of temporal energy with an evaluation of spectral energy in the PCG data.

Abstract: A solid-state defibrillation circuit for applying a multiphasic defibrillation pulse to a patient is disclosed. The circuit eliminates the need for a mechanical relay, and provides for a current limiting circuit for limiting leakage currents that would otherwise flow to the patient from the solid-state components, and for preventing the short-circuiting of a defibrillation pulse from a second defibrillator. In one embodiment, the output circuit of the defibrillator comprises an H-bridge, and the current limiting circuit comprises a plurality of resistors coupled in parallel with each of the legs of the H-bridge. The plurality of resistors allow current flow which reduces the voltage potential across the patient that is caused by the leakage currents through the output circuit. The current limiting circuit also includes a shunt resistor for shunting leakage currents away from the patient.

Abstract: The present invention is directed to a defibrillator having both a manual and an AED mode with corresponding user commands for both modes. The defibrillator includes a door which conceals manual mode commands, such that opening of the door puts the defibrillator in the manual mode and simultaneously reveals the manual mode command buttons. In one actual embodiment, the door includes apertures which allow access to the AED command buttons. When the door is in the open position, a keypad is revealed having manual commands which preferably take the form of buttons. In another actual embodiment, the door includes a switch which senses when the door is opened and sends the defibrillator into manual mode. The door includes a front side having AED command buttons, and a back side having manual mode command buttons. The door conceals a keypad having further manual mode command buttons.

Abstract: A method and apparatus that automatically detects whether a load connected to a defibrillator is a patient or a test device measures a load-dependent electrical parameter, such as impedance, by delivering to the load at least two small-amplitude signals, each having different frequencies. Because the impedance of a patient is complex, impedance measurements obtained from the small-amplitude signals delivered to the load will differ if the load is a patient. If the impedance measurements obtained from the small-amplitude signals are approximately equal, the load is determined to be a test device. In an alternative embodiment, a small signal impedance measurement may be compared with an impedance measurement obtained from application of a high-amplitude signal to the load. Differing measurements indicate that the load is a patient, while impedance measurements that are approximately equal indicate that the load is a test device.

Abstract: An automated external defibrillator (AED) (10) designed for use by a rescuer with minimal or no training during a medical emergency is provided. The AED implements a user interface program (22) which guides the rescuer through operation of the AED and application of CPR and defibrillation therapy to a patient by displaying a series of visual instructions on a graphic display (14) or other visual output device, and by providing additional aural instructions via a speaker (18) or other aural output device. The rescuer merely needs to press a start button (12) to initiate operation of the AED and begin CPR and defibrillation instruction.