Abstract: Method and apparatus for transcutaneously pacing the heart using two or more pairs of electrodes to reduce patient discomfort during pacing. The pacing stimuli are divided into two or more series of pulses, with at least one series of pulses being delivered by an electrode pair that differs from an electrode pair delivering another series of pulses. Typically, the electrode pairs are arranged so that current paths between electrodes in each pair of electrodes intersect at the patient's heart.

Abstract: A defibrillator with an alarm driven by both a heart rate detector and a fibrillation/tachycardia advisory algorithm. The defibrillator is a semiautomatic. By driving the alarm from both sources, the operator is provided with more information; instead of simply being advised of the onset of fibrillation or shockable tachycardia, the operator of a semiautomatic defibrillator is now also advised of the onset of asystole, bradycardia, and nonshockable tachycardia (e.g., superventricular tachycardia). The advisory algorithm can often provide a more timely indication of the onset of an abnormal rhythm than can the conventional heart rate detector, which relies on averaging over multiple heart beats, and thus is slow to detect a change in waveform. And, the advisory algorithm will sometimes detect an abnormal ECG that would have gone undetected by a conventional heart rate alarm.

Abstract: An electrode for transcutaneously delivering defibrillation pulses to a patient's heart. The electrode comprises an insulating substrate, a conducting plate which is positioned on the substrate and which has an electrical terminal for making a connection to an external source of electrical current, and a layer of electrolytic gel covering the entire top surface of the conducting plate. This gel contacts a patient's skin when the electrode is positioned on the skin to prevent the conducting plate from contacting the skin. The gel comprises a concentration of an electrolyte such that the combination series resistance of two of the electrodes, when measured with the electrodes configured in a series circuit with a 50 .OMEGA. resistance, and with the electrolytic gel layer of each electrode in contact with that of the other electrode, is greater than 1 .OMEGA. when a 200 Joule defibrillation pulse is discharged into the series circuit.

Abstract: Apparatus for transcutaneously pacing and defibrillating the heart of a patient, having defibrillation pulse discharge circuitry 30 and pacing stimuli generator circuitry 42, both circuits having positive and negative connections 40A, 40B, and 46A, 46B; and including a first multipin connector 49 having four pins at each of which one of the four connections is supplied; a second multipin connector 53 configured to mate with the first multipin connector, and having internal connections to electrically connect the positive connections for the pacing and defibrillation circuitry 40A, 46A and likewise connecting the negative connections of the pacing and defibrillation circuitry 40B, 46B, wherein the positive and negative multifunction connections 58A, 58B are suited for connecting to multifunction electrodes through which both pacing stimuli and defibrillation pulses may be supplied; and a third multipin connector 12 also configured to mate with the first connector, but configured to isolate the pacing connectio

Abstract: Method and apparatus for transcutaneously pacing the heart with background stimuli occurring in the intervals between pacing stimuli to reduce patient discomfort during pacing, and including electrodes therefor.

Abstract: Method and apparatus for detecting the open or closed state of a pair of manually-operated switches 116, 118 associated with a pair of defibrillation pulse electrodes, the switches being normally open and being manually closed by an operator, the two switches connected in series with discharge control circuitry 32 for initiating a defibrillation energy pulse. The control circuitry 32 is configured so that when the switches 116, 118 are both closed a defibrillation pulse is initiated. Each of the switches is connected in parallel with a corresponding circuit element 124, 126, each having a characteristic impedance, and being shorted out when the corresponding switch 116, 118 is closed. The invention provides for measuring an indication of the series impedance of the discharge control circuitry 32 to determine the open or closed state of the switches by comparing a measured impedance value indication with an impedance value indication calculated for a given open or closed state of the switches.

Abstract: Method and apparatus for discharging a defibrillation discharge circuit 30 across a short circuit load 166 for monitoring defibrillation pulses 180 generated by the circuit to test that the pulses are acceptable. The discharge circuit 30 comprises an electrical capacitor 34 for storing defibrillation pulse energy and an electrical inductor 38 in series with the capacitor for shaping the discharge pulses. In the invention, parameters representative of the shape of the defibrillation pulse are detected as the pulse is discharged and are compared to predetermined values characteristic of the shape of an acceptable pulse. Based on the outcome of this comparison, an output is provided indicating whether the pulse is acceptable.

Abstract: Method and apparatus for determining the current in a defibrillation pulse discharge circuit 30 which has an inductor 38 with a characteristic inductance for shaping the defibrillation pulses. A sense winding 136 is wound around the inductor with at least one turn between ends of the winding for developing a sense voltage between the ends in response to the current in the inductor as a defibrillation pulse is discharged by the circuit. This sense voltage is measured, and based on the sense voltage and the characteristic inductance of the inductor, the current in the defibrillation discharge pulse is determined.

Abstract: Method and apparatus for transcutaneously pacing the heart with pacing stimuli each of which comprise a series of individual pulses. The heart reacts to the series of pulses as if the series were one continuous pulse, whereas the pulse series produces skeletal muscle reactions that are similar to that which would be expected for individual pulses. The result is reduced stimulation of skeletal muscles and nerves, and less discomfort for the patient. Further reduction in stimulation of skeletal muscles and nerves can be achieved by providing a series of subthreshold initial pulses in each pacing stimulus.