Probabilistic model of electric current inducing ventricular fibrillation in human hearts

摘要

The article discusses the factors and circumstances which are decisive for the value of the current which induces ventricular fibrillation. It presents an analytical description of a probabilistic model of currents causing ventricular fibrillation in human hearts. The model includes the following types of shock currents: sinusoidally alternating and direct currents, short-duration current impulses during discharging a capacitor by a human body. An analytical description is provided of the dependence of the median values of the fibrillation current on: the shock duration time, the route the current takes through the body, the individual's weight, the type of current, and, in the case of the alternating current, on its frequency. Dependencies for calculating standard deviation of the conditional logarithm-normal distribution of the fibrillation current values are given. With the use of the developed probabilistic model, the latest IEC provisions concerning fibrillation current quantiles are approximated. A graphical interpretation is included of a probabilistic model of fibrillation currents in the form of the Bayesian network which makes it possible to perform cause and effect reasoning. The authors present exemplary dependencies for such reasoning; for effect reasoning - dependencies concerning the function of the random value probability density of fibrillation currents for the pre-defined probability of occurrence of the given shock conditions, for cause reasoning - dependencies referring to the probability of occurrence of the given shock conditions for the pre-defined probability of occurrence of fibrillation current values.