Abstract: A medical device (e.g., an automated external defibrillator) automatically detects and reports cardiac asystole by first obtaining ECG data and calculating one or more ECG measures from the ECG data. The defibrillator evaluates the ECG data by classifying the ECG data into a class indicative of cardiac condition, wherein one class is indicative of cardiac asystole. If the defibrillator classifies the ECG data into the class indicative of cardiac asystole, the defibrillator reports the asystole classification on a display. The defibrillator may classify the ECG data into a rhythm class associated with a cardiac rhythm, such as asystole, and report the rhythm class of the ECG data on the display. The defibrillator may also suggest a procedure to undertake, such as a therapy (e.g., defibrillation for a shockable cardiac rhythm), based on the classification of the ECG data.

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: An ECG signal measuring system uses low frequency compression/enhancement techniques combined with dither techniques to effectively increase the dynamic range while maintaining resolution. This aspect of the present invention is achieved without increasing the number of bits of the ADC. The system includes a HPF, an ADC, a decimation filter (DF), and a compensation filter (CF). The HPF receives an input signal (i.e., the bias current combined with ECG input signal) and attenuates the low frequency components of the input signal, including a portion of the frequency band within the desired ECG frequency band. The ADC oversamples the output signal of the HPF. The DF receives the output samples of the ADC and generates output samples at rate that is at least twice the maximum frequency of the desired ECG output signal. The CF amplifies the low frequency end of the DF output samples.

Abstract: A reduced lead set device (10) that detects and reports the presence of an acute cardiac ischemic condition in a patient includes a reduced set of sensing electrodes (12, 14, 16, 18, and 20) placed on a patient for acquiring ECG data from the patient. The reduced lead set device evaluates the ECG data on a reduced set of leads by analyzing local features and/or global features of the ECG data. Local features may include local morphological measures such as ST elevation and clinical information on the patient such as age and sex. Global features include projection coefficients calculated from projecting a concatenated vector of heartbeat data onto separate sets of basis vectors that define signal subspaces of ischemic and non-ischemic ECGs. One or more classifiers evaluate the local features and/or global features to determine whether an acute cardiac ischemic condition is detected. The operating point, i.e., sensitivity and specificity, of the reduced lead set device is adjustable.

Abstract: A smart battery that self-monitors and maintains information about itself that includes its state of charge, its need for maintenance, and for conditions that indicate that it has reached the end of its useful life and should be discarded. The information maintained by the battery is then either displayed on an on-board display or is communicated to another device on a communication bus. The state of charge quantifies the smart battery's ability to reliably deliver charge to a host device and is dynamically adjusted over the lifetime of the smart battery. The state of charge may not exceed a full charge capacity value maintained by the smart battery and initially set to an estimated value. This full charge capacity value is dynamically adjusted throughout the life of the smart battery using information accumulated and maintained by the smart battery that indicates the smart battery's actual performance during use and by using messages received from a battery maintenance and testing system.

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 smart battery that self-monitors and maintains information about itself that includes its state of charge, its need for maintenance, and for conditions that indicate that it has reached the end of its useful life and should be discarded. The information maintained by the battery is then either displayed on an on-board display or is communicated to another device on a communication bus. The state of charge quantifies the smart battery's ability to reliably deliver charge to a host device and is dynamically adjusted over the lifetime of the smart battery. The state of charge may not exceed a full charge capacity value maintained by the smart battery and initially set to an estimated value. This full charge capacity value is dynamically adjusted throughout the life of the smart battery using information accumulated and maintained by the smart battery that indicates the smart battery's actual performance during use and by using messages received from a battery maintenance and testing system.