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: 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 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: 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.