(183b) Evolution of Dilatational Rheology of Lung Surfactant Film as Acute Respiratory Distress Syndrome (ARDS) Progresses

As acute respiratory distress syndrome (ARDS) progresses, the elasticity of the surfactant layer covering the alveoli becomes compromised, which often leads to alveolar collapse. The elevated amount of serum proteins and lysolipids in the lung disrupts the interfacial film through adsorption of these inflammatory products and subsequent desorption of the main lipid components of lung surfactant. Dilatational rheology is a useful tool to probe the relevant stiffness change associated with these processes. In my talk, I will revisit how Langmuir trough can be effectively used as a dilatational rheology probe, addressing the commonly argued shear effects on such measurements, followed by my preliminary measurements on different surfactants, either soluble or insoluble. Our results demonstrate that a main lung surfactant lipid (DPPC) film loses its dilatational elasticity (E=200 mN/m) over the course of twelve hours since lysolipid is introduced to the system, bringing the film’s dilatational modulus value close to that of pure lysolipid (E=50 mN/m). We will relate the change in this rheological property to the change in interfacial morphology. These understandings are crucial in formulating synthetic lung surfactant replacement that can both treat respiratory distress syndromes effectively and prevent alveolar collapse.