Construction of a hybrid lung model by combining a real geometry of the upper airways and an idealized geometry of the lower airways

Agujetas, Rafael; Perotti, Raúl Barrio; Ferrera, C.; Pandal, Adrián; Walters, D. Keith; Tena, Ana Fernández

doi:10.1016/j.cmpb.2020.105613

Cited by 12 publications

(8 citation statements)

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“…This means that the differential pressure force required to break a droplet is greater than the surface tension required to maintain the integrity of the droplets, and it is difficult for the upper respiratory tract to maintain the integrity of sputum. In contrast, for the bronchus of the distal lung, D ∼ 10 –3 m, A ∼ 10 –6 m 2 and Δ p ∼ 10 0 Pa (Agujetas et al , 2020), so Δ F = Δ pA ∼10 –6 N and F σ = σD ∼ 10 –5 N. Thus, Δ F < F σ . This means that the differential pressure force of the broken droplets is less than the surface tension required to maintain the integrity of the droplets, so the sputum maintains integrity.…”

Section: Discussionmentioning

confidence: 95%

Study of the flow mechanism and influencing factors of sputum excretion from the distal lung

Jin

Cui

Chen

et al. 2022

HFF

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Purpose The purpose of this paper is to study the mechanism of efficient sputum excretion from the distal lung by using a tessellationally distal lung model with alveolar pores. Design/methodology/approach First, a two-dimensional tessellational composite structure of the bronchus, alveoli and alveolar pores (Kohn pore) is constructed with the tessellational splitting and fusion of regular hexagonal elements. Then, the level set method is used to study the effects of alveolar pores and their sizes, expiratory cycles and respiratory intensity. Findings The existence of alveolar pores is the prerequisite for sputum excretion, and there is an optimal size of alveolar pores for sputum excretion. Strong asymmetric respiration can break the reversibility of the flow at a low Reynolds number and causes significant net displacement of sputum. The expiratory cycle is negatively correlated with the net displacement of sputum. The respiratory intensity is positively correlated with the net displacement of sputum. Originality/value This research is helpful for understanding the complex sputum excretion process in diseases, such as pneumonia, and developing corresponding adjuvant therapy.

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Section: Discussionmentioning

confidence: 95%

Study of the flow mechanism and influencing factors of sputum excretion from the distal lung

Jin

Cui

Chen

et al. 2022

HFF

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“…However, the most commonly used simplification is the adoption of rigid airway walls. 39,47,61 While this enables the simulation of dynamic flows in the 3D od quasi-3D patient-specific structures of the bronchial tree by means of computational fluid dynamics (CFD), 7,9,12,13,[29][30][31][32][33][34][35]36,[51][52][53][54][55][56][57] it does not take into account the aforementioned changes in the bronchial properties caused by variations in pressures and flow, or the associated lung volume. This disadvantage is not present in simulations using fluid-structure interactions (FSI) that allow for the 3D geometry and flexibility of the bronchi to be taken into account.…”

Section: Discussionmentioning

confidence: 99%

“…19,20,24,28,42,[48][49][50] Moreover, even using the morphology-based models, their structure was kept only for the first generations of conducting airways with combined or omitted smaller bronchioli, [10][11][12][13]16,17,32,37,21,28,48,49,51 or alternatively the acinar region was only taken into account. 27 The second type of simplifications was based on the assumption of rigid walls of the airways, 13,32,33,35,47,48,[51][52][53][54][55] analyzing the system for a single lung volume or constant flow. 10,19,21,53,55,58 Among these approaches, the quasi-3D model using plenty of wires to simplify fluid dynamics simulations, 56 has proved particularly successful.…”

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confidence: 99%

Algebraic approximation of the distributed model for the pressure drop in the respiratory airways

Polak

2022

Numer Methods Biomed Eng

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The complexity of the human respiratory system causes that one of the main methods of analyzing the dynamic pulmonary phenomena and interpreting experimental results are simulations of its computational models. Among the most compound elements of these models, apart from the bronchial tree structure, is the phenomenon of flow limitation in flexible bronchi, which causes them to collapse with increasing flow, thus their properties, such as resistance, compliance and inertance, are highly nonlinear and time‐varying. Commonly, this phenomenon is ignored, or a distributed model for the airway pressure drop is applied, simulated with a modified numerical solver of this differential equation (ODE). The disadvantages of this solution are the problems with taking into account the inherent singularity of the model and the long computation time due to iterative nature of the ODE procedure. The aim of the work was to derive an algebraic approximation of this distributed model, suitable for implementation in continuous dynamic models, to validate it by comparing the results of simulations with the respiratory system model including approximate and original (ODE solver) numerical procedures, as well as to evaluate possible acceleration of calculations. All simulations, including spontaneous breathing, mechanical ventilation with the optimal ventilatory waveform and forced expiration, proved that algebraic approximation yielded results negligibly differing from the ODE solution, and shortened the computation time by an order. The proposed approach is an attractive alternative in the case of computer implementations of pulmonary models, where simulations of flows and pressures in the complex respiratory system are of primary importance.

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“…They are the main structure of the local innate immune system and the main carrier of the airway flora. There are cilia on the surface of respiratory mucosal epithelial cells, which can transport bacteria of the lower airway upwards, while the mucus secreted by goblet cells and secretory IgA antibodies produced by submucosal lymphohistiocytes can further maintain the local chemical immune barrier function of the mucosa and prevent the invasion and colonization of pathogens [ 13 , 14 ]. However, the local immune system of the airway neither equips with the strong acid and alkali on the surface of alimentary canal mucosa and the powerful germicidal mechanism of excellent enzyme system nor the extremely anaerobic environment, which determines that there is no significant difference in the species but only in the number of bacteria in the upper and lower airway.…”

Section: Flora Distribution and Local Immunity Of The Airway In Healthy Peoplementioning

confidence: 99%

The Role of Respiratory Flora in the Pathogenesis of Chronic Respiratory Diseases

Guo

Chen

Ying

et al. 2021

BioMed Research International

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Large quantities of bacteria, including Firmicutes, Actinobacteria, and Bacteroidetes, colonize the surface of the respiratory mucosa of healthy people. They interact and coexist with the local mucosal immune system of the human airway, maintaining the immune stability and balance of the respiratory system. While suffering from chronic respiratory diseases, the microbial population in the airway changes and the proportion of Proteobacteria is increased in patients with asthma. The abundance of the microbial population in patients with chronic obstructive pulmonary disease (COPD) is decreased, and conversely, the proportion of Firmicutes and Proteobacteria increased. The diversity of airway microorganisms in cystic fibrosis (CF) patients is decreased, while pathogenic bacteria and conditional pathogenic bacteria are proliferated in large numbers. The proportion of Firmicutes and Proteobacteria is increased in patients with upper airway cough syndrome (UACS), which replaces the dominance of Streptococcus and Neisseria in the pharynx of a normal population. Therefore, a clear understanding of the immune process of the airway flora and the immune dysfunction of the flora on the pathogenesis of chronic respiratory diseases can provide new ideas for the prevention and treatment of human respiratory diseases.

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Construction of a hybrid lung model by combining a real geometry of the upper airways and an idealized geometry of the lower airways

Cited by 12 publications

References 50 publications

Study of the flow mechanism and influencing factors of sputum excretion from the distal lung

Study of the flow mechanism and influencing factors of sputum excretion from the distal lung

Algebraic approximation of the distributed model for the pressure drop in the respiratory airways

The Role of Respiratory Flora in the Pathogenesis of Chronic Respiratory Diseases

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