Effect of high levels of film compression on surfactant transport

A previously developed adsorption-limited model [Otis, 1994; Ingenito, 1999] that describes the transport of lung surfactant to and from an air-liquid interface has been extended to allow for diffusion in the bulk phase. We used this model to compare to experimental data from Schurch [1989]. We find that high levels of film compression lead transiently to large changes in adsorption rate, desorption rate and diffusion constant, consistent with what might expected if a selected purification of the interface was occurring leading to DPPC enrichment of the interface. The collapse of the surfactant film that occurs during compression leads to a significant elevation of surfactant concentration immediately underlying the interface, consistent with the formation of a subsurface deposit of surfactant