Design for a constant peak current defibrillator.

A damped sine wave defibrillator that is capable of delivering a constant peak discharge current over a wide range of patient thoracic impedance is shown to be theoretically possible. This is realized in practice by the technique of storing an amount of energy above that required for delivery, and dumping the excess charge when the discharge current has reached a predetermined level, the dumping being triggered by a current sensor. A larger than normal inductance assists in swamping the effect of varying impedance and produces a smooth waveform. The preselected peak current can be delivered with a variation of about +/- 6% to 95% of a normal patient population. The energy expended in a simulated patient circuit is somewhat lower than for conventional defibrillators.