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Related Experiment Video

Updated: Jul 17, 2026

Surfactant Depletion Combined with Injurious Ventilation Results in a Reproducible Model of the Acute Respiratory Distress Syndrome (ARDS)

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Published on: April 7, 2021

Dynamic behavior of lung surfactant.

J Morris¹, E P Ingenito, L Mark

¹Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge 02139, USA.

Journal of Biomechanical Engineering

|March 30, 2001

Summary

This study enhances a lung surfactant model to include liquid phase diffusion, revealing its importance in transient dynamics and surfactant behavior during compression. The improved model accurately describes oscillatory surfactometer data, including pseudo-film collapse.

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Published on: July 11, 2025

Area of Science:

Biophysics
Respiratory Physiology

Background:

Lung surfactant dynamics at the air-liquid interface are crucial for respiratory function.
Previous models focused on adsorption limitations, neglecting liquid-phase transport.

Purpose of the Study:

To extend an existing lung surfactant model by incorporating diffusion in the liquid phase.
To investigate the role of diffusion-limited transport in surfactant exchange dynamics.
To improve the characterization of transient periods and steady-state conditions in oscillatory surfactometers.

Main Methods:

Development of an extended adsorption-limited model incorporating liquid-phase diffusion.
Application of the model to analyze existing experimental data from oscillatory and pulsating bubble surfactometers.
Analysis of surfactant behavior, including adsorption/desorption rates and diffusion constants, under varying film compression levels.

Main Results:

Diffusion-limited transport is critical for characterizing the transient phase from oscillation initiation to steady-state.
High film compression significantly alters adsorption, desorption rates, and diffusion constants, suggesting subsurface enrichment (e.g., DPPC).
Surfactant film collapse leads to increased sub-surface surfactant concentration, supporting the existence of a surfactant depot.
A phenomenon termed "pseudo-film collapse" was identified, where interfacial tension remains constant during compression without film collapse due to desorption.

Conclusions:

The enhanced model provides a more accurate description of lung surfactant exchange, particularly during transient periods.
The model supports the hypothesis of a subsurface surfactant depot and explains observed phenomena like pseudo-film collapse.
Incorporating liquid-phase diffusion significantly improves agreement with experimental data from various surfactometer setups.