Comparison between two defibrillation waveforms.

Two defibrillation waveforms, the chopped biphasic pulses and the constant current pulses, were assessed and compared. Two indices are introduced. The first one is the ratio between the delivered energy W and the energy W(0) of a rectangular pulse with the same duration and electric charge. The second index η(C) = W(0)/W(C0) stands for the level of utilizing the initially loaded capacitor energy W(C0). Some design considerations are also discussed. Another aspect of the study is the choice of appropriate capacitor for pulse generation. The results obtained show that there is no outstanding optimal waveform. The W/W(0) ratio is higher for the known constant current shapes but specifically with a patient resistance lower than 80 Ω. On the other hand, the implementation of these shapes would face several difficulties. The chopped biphasic waveforms are obtained by relatively simple technical solutions leading to very small in size and weight portable instruments.