(M-484) The Fabrication of a Breathing Neonate Lung Model

Introduction:: Introduction Pulmonary surfactant is produced by alveolar type II cells and secreted to the air-liquid interface to decrease the surface tension forces and prevent them alveoli from collapsing during exhalation. Neonatal respiratory distress syndrome (RDS) is a breathing disorder most seen in premature newborns due to immature lungs. The disease is caused by the lack of surfactant production in the alveoli and is associated by labored breathing and low oxygenation of blood. The treatment is known as surfactant replacement therapy that involves the administration of an exogenous surfactant to through the trachea ¹. The surfactant is typically given in liquid form to form a bolus in the trachea and pushed down toward alveoli using forced air. Due to potential damaging effects of ventilation pressures to delicate airways and alveoli tissues in neonates, there is a need to investigate the efficacy of surfactant replacement therapy in an aerosolized form. The objective of this study is to develop a breathing neonate lung model for quantitative studies the efficiency of aerosolized surfactant delivery.


Materials and Methods:: Methods and Materials: A four-generation, 3D, symmetric model of neonate lung airways was developed in SolidWorks and fabricated a semi-transparent material known as Clear V4 resin using 3D printing. Airways on left and right lungs were housed within a compliant balloon. To simulate breathing, an artificial diaphragm was constructed. Varying the air volume in the controlled space was used to simulate breathing.


Results, Conclusions, and Discussions:: Results: We successfully a computational 4-generation lung airway model of neonates (Figure 1a). This model has similar dimensions to neonates’ airways in terms of length and diameter of airways and branching angle between each two daughter airways emerging from a parent airway. The trachea is 3.5 mm in diameter and 17.5 mm in length. Subsequent airways reduced in diameter according to < ![if !msEquation] >< ![if !vml] >< ![endif] >< ![endif] > , where < ![if !msEquation] >< ![if !vml] >< ![endif] >< ![endif] > denotes airway generations (1,2,3,4), < ![if !msEquation] >< ![if !vml] >< ![endif] >< ![endif] > is tracheal diameter, and < ![if !msEquation] >< ![if !vml] >< ![endif] >< ![endif] > is diameter of each airway generation ^1,2. The length-to-diameter ratio of all airways, except trachea, was 3.0. We used 3D printing with a liquid resin to construct a physical model of the airways (Figure 1b). Following the construction of the in-house lungs and diaphragm, we demonstrated basic simulated breathing by changing manually expanding and contracting the airspace within the container housing the airways (Figure 2).

Discussion: We used the basic simulated breathing model containing the 4-generation lung model to create a breathing neonate lung. We are currently developing a more advanced breathing lung model to accurately change the air volume to represent intrapleural pressures during respiration. This will allow us to measure and manipulate the volumes and pressures similar to those in preterm infants for the studies of aerosolized surfactant delivery.

Conclusions: A breathing neonate lung model that allows us to simulate breathing was fabricated. Due to the ability to manipulate the pressure and volume, the lung model created can resemble premature lungs as well as term lungs. This model will be used with different nebulizers to study the efficiency of aerosolized drug delivery in neonate lungs.


Acknowledgements (Optional): : Acknowledgements: Financial support from NSF grant 1904210.


References (Optional): : References:

1. Copploe, A. et al., Ann Biomed Eng, 2019, 47: p. 1435-1445.

2. Weibel, E.R et al., Science, 1962. 137: p. 577-585.