Current Defibrillator: New Instrument of Programmed Current for Research and Clinical Use

Today, the instrumentation for electrical defibrillation has reached, with capacitor discharge defibrillators, a high technological level. However, these equipments have some limitations when it is wanted to preset a fixed current because of the dependence, both of the current and the time constant, on the load between electrodes. A current defibrillator, based upon a current generator instead of a voltage one, overcomes this limitation because the current discharged is preset before the operation, and hence, it is independent of the load circuit parameters. This paper presents the theoretical analysis and technical considerations of a current-controlled defibrillator. The instrument is based on the principle of electromagnetic impulse conservation in an inductor L (L 220 mH), which is charged with a preset current and, thereafter, discharged through the paddles and load giving an exponential decay waveform. The peak value of the current is independent of the load and it ranges from 2 to 60 A. The load can vary from 15 to 101 Ω for transventricular and transthoracic defibrillation.