A computationally tractable scheme for simulation of the human pulmonary system

Highlights: • The pulmonary system can be simulated by connecting distinct models together. • Simulating blood flow models in a GPU environment allows for tractability. • Airflow and pulmonary blood flow do not necessarily follow similar distributions. -- Abstract: The accurate analysis of patient lung structure and morphology in a clinical setting is one of the significant challenges in pulmonary medicine. In recent years, computational modelling techniques have been shown to help improve understanding of function-form relationships within the lungs, and of the underlying sensitivities of pulmonary function test responses to pulmonary disease. A large array of literature has been dedicated to modelling airflow and gas transfer within the lungs, and within vasculature. However, little work exists connecting the two systems together, particularly in computationally tractable ways. Within this study we outline a numerical scheme for modelling gas transport throughout the airways, pulmonary arterial network, and across the alveolar-capillary membrane. Through careful scheme design, and the application of high-performance computing structures, we show how these models can remain tractable, even when simulating to quite fine resolution. Following model development and error analysis, we apply the model to the simulation of the multiple-breath washout, a common pulmonary function test, illustrating how the choice of tracer gas may affect clinical diagnosis measures.