Abstract: When a defibrillator selects a dosage of energy or current to be delivered to a patient, the defibrillator selects an excitation current frequency and applies the excitation current at the selected frequency to the patient. The frequency of the excitation current is selected as a function of the dosage to be delivered. The patient's response to the excitation current at the selected frequency will accurately reflect the impedance that the defibrillator will “see” when delivering the selected dosage of energy or current.

Abstract: In general, the invention facilitates improved inter-module communication within a medical device system, such as an automated external defibrillator (AED), by using a serial data interface based on the USB specification to transfer data between modules. As a result, data transmission rates may be improved significantly, thereby providing ample communication bandwidth for a variety of medical device applications. Further, the serial interconnect nature of the USB interface reduces the number of physical interconnects that are needed to support the interface, thereby reducing the design constraints on the medical device system.

Abstract: The invention presents techniques for identifying signals detected by electrodes on the body of a patient as part of a reading of the patient's electrocardiogram. A signal processor digitally filters the signal from the body, resulting in an electrocardiogram signal and a signal that identifies the presence and timing of signals from a pacemaker in the body. Other signals, such as a signal that reflects the quality of the electrical connection of the electrode to the body, may also be obtained by digital filtering.

Abstract: When a defibrillator selects a dosage of energy or current to be delivered to a patient, the defibrillator selects an excitation current frequency and applies the excitation current at the selected frequency to the patient. The frequency of the excitation current is selected as a function of the dosage to be delivered. The patient's response to the excitation current at the selected frequency will accurately reflect the impedance that the defibrillator will “see” when delivering the selected dosage of energy or current.

Abstract: In general, the invention facilitates improved inter-module communication within a medical device system, such as an automated external defibrillator (AED), by using a serial data interface based on the USB specification to transfer data between modules. As a result, data transmission rates may be improved significantly, thereby providing ample communication bandwidth for a variety of medical device applications. Further, the serial interconnect nature of the USB interface reduces the number of physical interconnects that are needed to support the interface, thereby reducing the design constraints on the medical device system.

Abstract: The invention presents techniques for identifying signals detected by electrodes on the body of a patient as part of a reading of the patient's electrocardiogram. A signal processor digitally filters the signal from the body, resulting in an electrocardiogram signal and a signal that identifies the presence and timing of signals from a pacemaker in the body. Other signals, such as a signal that reflects the quality of the electrical connection of the electrode to the body, may also be obtained by digital filtering.

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: A control circuit ideally suited for a capacitor charging circuit (100) that uses an apparent measure of current flow through a circuit line to regulate current drawn from a battery through the circuit line is disclosed. A summing circuit (136) produces a difference voltage (138) of the battery voltage (152) subtracted from a threshold reference voltage (151). The difference voltage (138) is subsequently amplified by an amplifier (140), rectified by a diode (142), and added to a voltage measure (130) from a current-sense resistor (117) by a summing circuit (128). The resulting voltage measure (126) is an apparent measure of current flow and is provided to a charge controller (122) which regulates current flow through a transformer (107) by controlling the operation of a switch (108).