In ARDS, what happens to surfactant?

In ARDS, what happens to surfactant?

• A. Surfactant is displaced
• B. Surfactant production increases
• C. Lung compliance increases
• D. No change in surfactant

Answer: (A)

In ARDS, surfactant is displaced from the alveolar surface by the protein-rich edema fluid that floods the airspaces. This fluid dilutes and inactivates surfactant and can wash it away from the air-liquid interface, so its ability to lower surface tension is lost. The result is higher surface tension, more alveolar collapse at end expiration, and reduced lung compliance with worse gas exchange. So the best description is that surfactant is displaced. Production typically doesn’t increase in this situation; injury to the alveolar cells and the inflammatory environment often impairs production, and compliance decreases rather than increases.

In ARDS, surfactant is displaced from the alveolar surface by the protein-rich edema fluid that floods the airspaces. This fluid dilutes and inactivates surfactant and can wash it away from the air-liquid interface, so its ability to lower surface tension is lost. The result is higher surface tension, more alveolar collapse at end expiration, and reduced lung compliance with worse gas exchange. So the best description is that surfactant is displaced. Production typically doesn’t increase in this situation; injury to the alveolar cells and the inflammatory environment often impairs production, and compliance decreases rather than increases.