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