A model of lung surfactant dynamics based on intrinsic interfacial compressibility

Abstract

A minimum model for the description of lung surfactant dynamics during consecutive compression/relaxation cycles is proposed. The model is based on Frumkin/Langmuir equilibrium and on an equation of state that includes rigorously the intrinsic compressibility of the densely packed monolayer. Adsorption/desorption dynamics is taken to be kinetically-limited, and film collapse during extreme compression is accounted for by a sublayer reservoir and a simple kinetic expression for monolayer replenishment during re-expansion. The model is validated and found to agree quantitatively with independent data in the literature, taken at physiologically relevant conditions. The best-fit values of the key model parameters are discussed and found to be physically meaningful. Finally, the characteristics of dilatational elasticity, as predicted by the model, are considered. © 2021 Elsevier B.V.