Three-dimensional model of surfactant replacement therapy

Area of Science:

• Pulmonary Medicine
• Biomedical Engineering
• Computational Fluid Dynamics

Background:

• Surfactant replacement therapy (SRT) is effective for neonatal respiratory distress syndrome (NRDS).
• SRT application in adults with acute respiratory distress syndrome (ARDS) has yielded inconsistent results, transitioning from success to failure.
• A key unresolved question is whether therapeutic surfactant reaches adult alveoli.

Purpose of the Study:

• To develop the first mathematical model of SRT in a 3D lung structure to investigate surfactant distribution in neonatal and adult lungs.
• To elucidate the reasons behind the differing outcomes of SRT in neonates versus adults.

Main Methods:

• Utilized fluid mechanics principles to model liquid plug propagation and surfactant deposition in 3D neonatal and adult lung airway trees.
• Simulated SRT procedures, analyzing liquid film coating and bifurcation splitting dynamics.
• Generated 3D images of acinar distribution and calculated efficiency and homogeneity indexes.

Main Results:

• The neonatal lung model demonstrated a well-mixed compartment, indicating efficient surfactant distribution.
• The adult lung model revealed incomplete mixing, suggesting inadequate surfactant delivery.
• Simulated early successful adult SRT protocols showed good index values, while later failed protocols exhibited very low values.

Conclusions:

• The adult lung's complex airway structure and gravitational effects impede efficient surfactant delivery compared to the neonatal lung.
• Differences in procedural methods and lung anatomy explain the historical shift from SRT success to failure in adult ARDS.
• The model provides a framework for understanding and potentially improving SRT protocols for adult ARDS.