A Variable Compliance Lung Model

Abstract

A lung analog having a known compliance is useful for teaching respiratory mechanics and for testing and periodic maintenance of mechanical ventilators. Rigid chambers have been employed for many years as compliance elements, 1.2 and the standard pub-lished recently by the American National Standards Institute (Z-79 Committee) describes a rigid-chamber model. Although such a model is rather simple and in-expensive, the use of a given rigid chamber provides only a single compliance. If one wishes to obtain several compliance val-ues, several different chambers must be used. A very simple and inexpensive model that we constructed in our department from readily available materials allows rapid and easy variability of compliance. Airway resistance can be simulated with the model by the placement of resistance units at the "upper airway" be-tween the model and the source of ventilation. These resistance units may be either the "linear" or "nonlinear" type (such as endotracheal tubes of different sizes).