How sighing regulates pulmonary surfactant structure and its role in breathing mechanics.

Summary

Using interfacial rheometry, in situ neutron reflectometry, and Raman analyses, the authors show that sighs enrich the air–liquid interface with saturated lipids and periodically reset the surfactant layer into a DPPC-rich, mechanically hardened film. This nonequilibrium reorganization reduces interfacial stress and supports high compliance, informing protective ventilation and surfactant therapy design.

Key Findings

• Sighs enrich the air–liquid interface with saturated lipids, triggering structural rearrangements.
• Periodic resets produce a DPPC-rich film exhibiting compressional hardening that counteracts interfacial tension.
• Interfacial compressive stresses, not only tension, are critical determinants of lung mechanics.
• Findings inform protective ventilation strategies and surfactant therapy optimization.

Clinical Implications

Supports incorporating controlled sighs or analogous maneuvers in lung-protective ventilation and inspires optimization of exogenous surfactant formulations toward DPPC-rich, compressively resilient films.

Limitations

• Preclinical biophysical systems without direct patient-level clinical outcomes.
• Injury/edema conditions of ARDS not fully replicated; translational dosing/implementation of sighs remains to be defined.

Future Directions

Test sigh protocols in lung-injury models and clinical trials; engineer surfactant formulations that favor DPPC-rich, compressively robust interfacial films.