Computer exploration of a model of explosive decompression.

Abstract

A model is explored describing the changes of volume and pressure in the lungs following explosive decompression. The model is based on two simultaneous nonlinear differential equations, and solutions are obtained on an analog computer. The values of two coefficients are estimated by bringing the radius of a sphere, equivalent in volume to the lungs, to a maximum at the same time as observed by means of high speed cinematography. Values of the instantaneous volume and transthoracic pressure difference, the derivatives of these variables with respect to time, and the time integral of the transthoracic pressure difference are estimated for 21 conditions of explosive decompression resulting in LD50 for rats. Measured variables and computed variables are combined in a multiple regression analysis yielding an empirical equation for prediction of LD50 conditions, which accounts for 98.5 per cent of the deviations from the mean. The model has descriptive and heuristic value for the estimation of physical characteristics of the lung-thorax system.