Gas transport in the air phase of the lung simulated by a digital computer

A nitrogen wash-out simulator has been worked out as a program for a digital computer. The structure of the simulator is based on the results of anatomical research. It imitates the anatomical model which Weibel designed and which is principally characterized by the dichotomic structure of the bronchial network. The parameters of this simulator are the end expiratory volume of the lung and the 16 specific ventilations of the ventilatory units. The values of these parameters are determined by adjustment of the simulated nitrogen wash-out and the experimental curves. To succeed in this analogy, we worked out a specialized program, which minimizes the sum of the squared deviations between the simulated and real points. In this case, the program minimizes a function of 16 independent variables, a problem which has no solution in general, but the particular structure of this simulator allows us to solve it. Applications to some concrete cases are shown.