Bond Graph Modeling of Lungs

In this modern era research in mechanical ventilator model designing has increased a lot. Mathematical model of lungs is used to distinguish the pulmonary diseases. In this work bond graph model of breathing mechanism i.e. inspiration and expiration of lungs is developed. Hydraulic analogies are allocated to lungs using cylinders and accumulators. From nostrils to trachea single cylinder is considered having resistance and compliance effect associated with it. Trachea to lower lung section comprised of 23 generations of airways. In this study, 2 generations are considered with resistance, compliance and inertial effect, whereas resistance and compliance effect, of 3rd to 17th generations are lumped. These generations are modelled with cylinders with decreasing sizes. 17 to 23 are modelled as accumulators with resistance and compliance. Model parameters were estimated using grey box estimation.20 sim is used to make the bond graph model and determine the relationship of pressure and volume curves. Model can be used for screening of lungs diseases. Model can be used for clinical trials with any existing mechanical ventilator.