Abstract: External pacemaker systems and methods deliver pacing waveforms that minimize hydrolysis of the electrode gel. Compensating pulses are interleaved with the pacing pulses, with a polarity and duration that balance the net charge at the electrode locations. The compensating pulses are preferably rectangular for continuous pacing, and decay individually for on-demand pacing.

Abstract: A cardiac therapy pulse delivery system includes a plurality of electrodes, an ECG signal processor circuit, and a pulse generator circuit. Each of the electrodes has at least one therapy element and at least one monitor element that are electrically insulated from one another. The ECG signal processor circuit is electrically coupled to each monitor element on each electrode and is operable to convert ECG signals detected by the monitor elements into ECG data. The cardiac pulse generator circuit is electrically coupled to each therapy element on each electrode and is operable to supply one or more cardiac therapy pulses thereto.

Abstract: Methods and apparatus are provided for minimizing the inherent time delays within external defibrillators. The methods and apparatuses utilize timing schemes for initiation and completion of charging of an energy storage device of an external defibrillator, measuring one or physical parameters of the patient and conducting a physiology analysis of the patient. The initiation and completion of one or more of these activities are arranged so that the energy storage device is charged to a desired level and available for a defibrillation shock to the patient with minimal delay after activation of the external defibrillator.

Abstract: An external defibrillator/pacer includes an output circuit with four legs arrayed to form an H-bridge. Each leg of the output circuit contains a switch. In a defibrillation mode, pairs of switches in the H-bridge are selectively switched to generate a biphasic defibrillation pulse. Three switches are silicon controlled rectifiers (SCRs). Gate drive circuits are coupled to the SCRs to bias the SCRs with a voltage that allows the SCRs in response to control signals. One switch includes an insulated gate bipolar transistor (IGBT). A gate drive circuit is coupled to the gate of the IGETs to provide a slow turn-on and a fast turn-off of the IGBT. In a pacing mode, a bypass circuit or current source circuit is used to provide a current path bypassing an SCR switch, which cannot be triggered by the relatively low current of pacing pulses.

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: 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: Methods and apparatus are provided for portable medical devices such as defibrillators having different charging and operating voltages. The apparatus comprises a connection for receiving DC input voltage VIN, an energy storage device (e.g., a capacitor), a battery having at least two cells therein coupled to the connection and the capacitor, and switches to selectively reconfigure the battery cells so as to: (i) charge from VIN, and (ii) discharge to the capacitor at VOUT>VIN. The method comprises charging the battery from VIN while its cells are arranged substantially in parallel, then reconfiguring the switches to arrange some of the charged cells substantially in series to give VOUT>VIN, and then charging the capacitor therefrom. The cells are thereafter reconfigured back to the parallel arrangement ready to be recharged from VIN. Isolation switches are conveniently provided to isolate the battery from VIN while charging the capacitor.

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: 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: An upgrade kit and method for converting a typical monophasic defibrillator into a biphasic defibrillator is provided. The upgrade kit is easily connected to a typical monophasic defibrillator and uses control signals that are commonly available in most monophasic defibrillators. Such control signals include the signals for transferring the defibrillation pulse to the patient, and for dumping unwanted energy from the energy storage capacitor. In addition, the upgrade kit avoids the need for information as to the charge level of the storage capacitor by using a discharge method that allows the production of proper biphasic defibrillation pulses regardless of the initial energy settings of the storage capacitor. More specifically, the upgrade kit determines the desired length of the biphasic defibrillation pulses according to two measurements which are taken during the defibrillation pulse.

Abstract: An upgrade kit and method for converting a typical monophasic defibrillator into a biphasic defibrillator is provided. The upgrade kit is easily connected to a typical monophasic defibrillator and uses control signals that are commonly available in most monophasic defibrillators. Such control signals include the signals for transferring the defibrillation pulse to the patient, and for dumping unwanted energy from the energy storage capacitor. In addition, the upgrade kit avoids the need for information as to the charge level of the storage capacitor by using a discharge method that allows the production of proper biphasic defibrillation pulses regardless of the initial energy settings of the storage capacitor. More specifically, the upgrade kit determines the desired length of the biphasic defibrillation pulses according to two measurements which are taken during the defibrillation pulse.

Abstract: An external defibrillator/pacer (8) includes an output circuit (14) with four legs arrayed to form an H-bridge. Each leg of the output circuit contains a switch (SW1-SW4). In a defibrillation mode, pairs of switches in the H-bridge are selectively switched to generate a biphasic defibrillation pulse. Three switches (SW1, SW3, SW4) are silicon controlled rectifiers (SCRs). Gate drive circuits (51, 53, 54) are coupled to the SCRs to bias the SCRs with a voltage that allows the SCRs in response to control signals. One switch (SW2) includes an insulated gate bipolar transistor (IGBT). A gate drive circuit (52) is coupled to the gate of the IGBTs to provide a slow turn-on and a fast turn-off of the IGBT. In a pacing mode, a bypass circuit or current source circuit is used to provide a current path bypassing an SCR switch (SW3), which cannot be triggered by the relatively low current of pacing pulses.

Abstract: A baseline wander filter (BWF) with linear phase response for an ECG signal measuring system includes two cascaded box car FIR filters to estimate the baseline wander. The cascaded box car filters form, in effect, a triangular FIR filter that generates a weighted sliding window average of the input samples to serve as the estimated baseline wander. The estimated baseline wander samples generated by the BWF are then subtracted from the corresponding input ECG samples. The boxcar filters can be designed to avoid multiplication by adding the samples and dividing the resulting sum by the number of coefficients. By choosing the number of coefficients as a power of two, binary division can be performed by shifting the bits of the resulting sum to the right. Accordingly, the present invention avoids the relatively large computational load of conventional FIR filter-based systems.

Abstract: A method and apparatus for providing automatic power switching in a portable external defibrillator is disclosed. The power supply switching circuit includes a plurality of power supply ports for receiving power sources such as batteries and external power sources. The power supply switching circuit works with both batteries that include monitoring devices (smart batteries) and batteries that do not include monitoring devices (dumb batteries). The power supply switching circuit also includes microprocessor controllable switches for selectively coupling the power supply ports to the output of the power supply switching circuit, and a microprocessor for controlling the switches and for monitoring the power supply ports. Resident in the microprocessor is a control program for controlling the switching and monitoring operations. The control program uses data received from the power sources to select the best available power source to be used as the output for the power supply switching circuit.

Abstract: An upgrade kit and method for converting a typical monophasic defibrillator into a biphasic defibrillator is provided. The upgrade kit is easily connected to a typical monophasic defibrillator and uses control signals that are commonly available in most monophasic defibrillators. Such control signals include the signals for transferring the defibrillation pulse to the patient, and for dumping unwanted energy from the energy storage capacitor. In addition, the upgrade kit avoids the need for information as to the charge level of the storage capacitor by using a discharge method that allows the production of proper biphasic defibrillation pulses regardless of the initial energy settings of the storage capacitor. More specifically, the upgrade kit determines the desired length of the biphasic defibrillation pulses according to two measurements which are taken during the defibrillation pulse.

Abstract: An external defibrillator/pacer (8) includes an output circuit (14) with four legs arrayed to form an H-bridge coupled to an energy storage capacitor. The energy storage capacitor delivers an external defibrillation pulse with stored energy during a defibrillation mode and an external pacing pulse during a pacing mode. Each leg of the output circuit contains a switch (SW1-SW4). In a defibrillation mode, pairs of switches in the H-bridge are selectively switched to generate a biphasic defibrillation pulse. Three switches (SW1, SW3, SW4) are silicon controlled rectifiers (SCRs). Gate drive circuits (51, 53, 54) are coupled to the SCRs to bias the SCRs with a voltage that allows the SCRs in response to control signals. One switch (SW2) includes an insulated gate bipolar transistor (IGBT). A gate drive circuit (52) is coupled to the gate of the IGBTs to provide a slow turn-on and a fast turn-off of the IGBT.

Abstract: A method and apparatus for monitoring an electrocardiograph waveform, and for returning an electrocardiograph trace to the middle of a display, such as a chart recorder strip. The monitoring circuit includes an amplifier and a switch for switching the frequency response curve of the monitoring circuit. In a first position, the switch causes the monitoring circuit to have a slow frequency response curve, which allows for accurate monitoring of ECG waveforms. In a second position, the switch causes the monitoring circuit to have a fast frequency response curve, which allows the amplifier of the monitoring circuit to quickly be brought out of saturation. The amplifier of the monitoring circuit becomes saturated when a defibrillation or pace pulse has been applied to a patient who is being monitored. The switch is controlled by a pulse waveform control signal that is provided by a microprocessor.

Abstract: A device (10) that detects and reports the presence of an acute cardiac ischemic condition in a patient includes sensing electrodes (12, 14, 16, 18, 20, 22, 24, 26, 28, and 30) placed on a patient for acquiring multiple (e.g., twelve) lead ECG data from the patient. The device evaluates the acquired ECG data by analyzing global features derived from the ECG data. Global features include projection coefficients calculated from projecting a concatenated vector of representative heartbeat data onto sets of basis vectors that define an acute cardiac ischemic ECG subspace and a non-ischemic ECG subspace. A classifier evaluates the global features to determine whether an acute cardiac ischemic condition is detected. In a further embodiment of the invention, one or more classifiers evaluate local features, such as local morphological features and patient clinical information, in addition to the global features to determine whether an acute cardiac ischemic condition is detected.

Abstract: An external defibrillator for applying a multiphasic defibrillation pulse to a patient uses a single semiconductor switching element in combination with a relay switching element. The semiconductor switching element is used to stop the flow of current from the energy storage device to the patient in between the phases of the multiphasic defibrillation pulse. The relay element is used to switch the leads of the energy storage device so as to create the different phases of the multiphasic defibrillation pulse. In various examples, the relay element is shown to be in the form of: a double-pole, double-throw relay; two single-pole, double-throw relays; or four reed relays. The timing between the activation of the semiconductor switching element and the relay switches may be delayed, so as to give the relatively slower relay switches time to respond.