evaluation of pulmonary surfactant mechanics under different inhaled environments via surface tension studies and light scattering

• Online Access: http://hdl.handle.net/2047/d20003108

In lung injury or trauma, oxygen is often administered in excessive amounts to relieve hypoxia. However, high concentrations of oxygen can be toxic to the lung and its prolonged exposures may be lethal. The harmful effect of oxygen has mostly been attributed to cellular damage and tissue inflammation. However, in some cases disruption in surfactant activity have also been reported. Pulmonary surfactant (PS) maintains stability and compliance of the lung by reducing surface tension at the air-liquid interface inside alveoli. Insufficient amounts of PS or a change in its behavior can cause severe damage to the lung and may result in reduced lung function. A recent study has utilized two different methods to show a change in PS function due to short periods of exposure (several tidal volumes) to 100% of oxygen through: (i) in-situ microscopic imaging of distal layers of alveoli during mechanical indentation using an optical coherence tomography (OCT) with an indenter tip (ii) surface tension studies on PS using a Langmuir-Wilhelmy (LW) balance. Results of these tests suggested a significant difference in the function of PS under oxygen, but left open key questions such as how an indenter tip can affect the OCT images and what the actual mechanism is for the interaction between oxygen and surfactant components. Therefore, addressing the unexplored issues in the previous study was the motivation for the current dissertation.