Computational Fluid Dynamics as an Emerging Supporting Clinical Tool: Review on Human Airways

Objectives: The main objective of this review article is to evaluate the usability of Computational Fluid Dynamics (CFD) as a supporting clinical tool for respiratory system. Data Source: The English articles referred for this review paper were identified from various International peer reviewed journals indexed in Science citation index. Study Selection: 26 high quality articles most relevant to the highlighted topic which were published in last fifteen years were selected from almost 120 articles. Results: The analysis done and the outcome obtained by this computational method is as accurate as Spirometry and Pulmonary function test (PFT) result. CFD can be very useful in the cases where patents is unable to perform PFT. Pressure drop, Velocity profile, Wall shear stress & other flow parameter, respiratory resistance, Pattern of drug deposition, Particles transport/deposition, etc. had also been predicted accurately using CFD. The effect of tracheal stenosis on the flow parameters has been predicted. The size and location of tracheal stenosis has also been correlated with breathing difficulties. The distribution of air in various lobes of the lungs can be accurately predicted with CFD tool. Conclusion: Virtual surgery is eventually possible by using CFD after further research with validation. With the help of this multi - disciplinary and efficient tool we can obtain accurate result while reducing cost and time

Structural and functional alterations of the tracheobronchial tree after left upper pulmonary lobectomy for lung cancer

© 2019 The Author(s). Background: Pulmonary lobectomy has been a well-established curative treatment method for localized lung cancer. After left upper pulmonary lobectomy, the upward displacement of remaining lower lobe causes the distortion or kink of bronchus, which is associated with intractable cough and breathless. However, the quantitative study on structural and functional alterations of the tracheobronchial tree after lobectomy has not been reported. We sought to investigate these alterations using CT imaging analysis and computational fluid dynamics (CFD) method. Methods: Both preoperative and postoperative CT images of 18 patients who underwent left upper pulmonary lobectomy are collected. After the tracheobronchial tree models are extracted, the angles between trachea and bronchi, the surface area and volume of the tree, and the cross-sectional area of left lower lobar bronchus are investigated. CFD method is further used to describe the airflow characteristics by the wall pressure, airflow velocity, lobar flow rate, etc. Results: It is found that the angle between the trachea and the right main bronchus increases after operation, but the angle with the left main bronchus decreases. No significant alteration is observed for the surface area or volume of the tree between pre-operation and post-operation. After left upper pulmonary lobectomy, the cross-sectional area of left lower lobar bronchus is reduced for most of the patients (15/18) by 15-75%, especially for 4 patients by more than 50%. The wall pressure, airflow velocity and pressure drop significantly increase after the operation. The flow rate to the right lung increases significantly by 2-30% (but there is no significant difference between each lobe), and the flow rate to the left lung drops accordingly. Many vortices are found in various places with severe distortions. Conclusions: The favorable and unfavorable adaptive alterations of tracheobronchial tree will occur after left upper pulmonary lobectomy, and these alterations can be clarified through CT imaging and CFD analysis. The severe distortions at left lower lobar bronchus might exacerbate postoperative shortness of breath

Computational Simulation: Selected Applications In Medicine, Dentistry, And Surgery

This article presents the use of computational modelling software (e.g. ANSYS) for the purposes of simulating, evaluating and developing medical and surgical practice. We provide a summary of computational simulation mo delling that has recently been employed through effective collaborations between the medical, mathematical and engineering research communities. Here, particular attention is being paid to the modelling of medical devices as well as providing an overview o f modelling bone, artificial organs and microvascular blood flows in the machine space of a High Performance Computer (HPC)

Elastocapillary network model of inhalation

The seemingly simple process of inhalation relies on a complex interplay between muscular contraction in the thorax, elasto-capillary interactions in individual lung branches, propagation of air between different connected branches, and overall air flow into the lungs. These processes occur over considerably different length and time scales; consequently, linking them to the biomechanical properties of the lungs, and quantifying how they together control the spatiotemporal features of inhalation, remains a challenge. We address this challenge by developing a computational model of the lungs as a hierarchical, branched network of connected liquid-lined flexible cylinders coupled to a viscoelastic thoracic cavity. Each branch opens at a rate and a pressure that is determined by input biomechanical parameters, enabling us to test the influence of changes in the mechanical properties of lung tissues and secretions on inhalation dynamics. By summing the dynamics of all the branches, we quantify the evolution of overall lung pressure and volume during inhalation, reproducing the shape of measured breathing curves. Using this model, we demonstrate how changes in lung muscle contraction, mucus viscosity and surface tension, and airway wall stiffness---characteristic of many respiratory diseases, including those arising from COVID-19, cystic fibrosis, chronic obstructive pulmonary disease, asthma, and emphysema---drastically alter inhaled lung capacity and breathing duration. Our work therefore helps to identify the key factors that control breathing dynamics, and provides a way to quantify how disease-induced changes in these factors lead to respiratory distress.Comment: In pres

Numerical simulation of human breathing and particle transport through a CT-based pulmonary airway geometry

Chronic respiratory illness afflicts more than a billion people worldwide. In recent years computational fluid dynamics (CFD) has been established as a paramount tool for studying treatments of respiratory illnesses. This work investigates physiologically appropriate, lobar-specific boundary conditions for numerical simulation of steady and unsteady flow through a computed tomography (CT) based pulmonary airway geometry. Particle transport is modeled in steady and unsteady flow. Analysis is conducted on flow phenomena and particle transport in both steady and inspiratory flow