Computational investigation of plug instillation into a physiologically representative infant airway tree model*

We present 3D multiphase flow simulations of liquid surfactant plug transport through a physically representative model of the human infant lung airway tree. Liquid surfactant instillation into the lung airways is used to treat respiratory distress syndrome (RDS) in preterm infants. The procedure, commonly known as surfactant replacement therapy (SRT), is used in the targeted delivery of surfactant plugs with the goal of achieving a uniform film distribution. SRT's effectiveness is tied to the successful plug propagation through each branching airway network. However, achieving uniform surfactant distribution is quite difficult with SRT having a 35% non-response rate. The challenge resides in overcoming naturally present asymmetries in the lung, which often lead to asymmetric plug propagation. We present computational simulations of plug instillation in a physiologically representative infant airway tree model, investigating effects of plug blockages and rupture on plug splitting and film distribution, with the goal of improving our understanding and the effectiveness of SRT.