Aerosol Deposition In Human Lung Research Articles

Experimental methods for flow and aerosol measurements in human airways and their replicas

Recent developments in the prediction of local aerosol deposition in human lungs are driven by the fast development of computational simulations. Although such simulations provide results in unbeatable resolution, significant differences among distinct methods of calculation emphasize the need for highly precise experimental data in order to specify boundary conditions and for validation purposes. This paper reviews and critically evaluates available methods for the measurement of single and disperse two-phase flows for the study of respiratory airflow and deposition of inhaled particles, performed both in vivo and in replicas of airways. Limitations and possibilities associated with the experimental methods are discussed and aspects of the computational calculations that can be validated are indicated. The review classifies the methods into following categories: 1) point-wise and planar methods for velocimetry in the airways, 2) classic methods for the measurement of the regional distribution of inhaled particles, 3) standard medical imaging methods applicable to the measurement of the regional aerosol distribution and 4) emerging and nonconventional methods. All methods are described, applications in human airways studies are illustrated, and recommendations for the most useful applications of each method are given.

Prediction of localized aerosol deposition in a realistic replica of human airways using experimental data and numerical simulation

The presence of aerosol deposition hot-spots in human airways presumably contributes to development of various diseases. The overall aerosol deposition in human lungs can be predicted with sufficient accuracy nowadays. However, the prediction of localized aerosol deposition poses arduous challenge, namely in diseased lungs. Numerical simulation is considered to be a promising tool for the successful prediction. Yet, the validation of such simulations is difficult to perform, as not enough experimental data acquired using realistic airway replicas is available. This paper presents a first comparison of localized deposition measurement and simulation performed on the identical realistic geometry. The analysis indicates that both approaches yield similar results for low Reynolds number flows.

Research of transport and deposition of aerosol in human airway replica

Growing concern about knowledge of aerosol transport in human lungs is caused by great potential of use of inhaled pharmaceuticals. Second substantial motive for the research is an effort to minimize adverse effects of particular matter emitted by traffic and industry on human health. We created model geometry of human lungs to 7th generation of branching. This model geometry was used for fabrication of two physical models. The first one is made from thin walled transparent silicone and it allows a measurement of velocity and size of aerosol particles by Phase Doppler Anemometry (PDA). The second one is fabricated by stereolithographic method and it is designed for aerosol deposition measurements. We provided a series of measurements of aerosol transport in the transparent model and we ascertained remarkable phenomena linked with lung flow. The results are presented in brief. To gather how this phenomena affects aerosol deposition in human lungs we used the second model and we developed a technique for deposition fraction and deposition efficiency assessment.

Computational Modeling of Aerosol Deposition in Respiratory Tract: A Review

This review article is intended to serve as an overview of the current status of the computational tools and approaches available for predicting respiratory-tract dosimetry of inhaled particulate matter. There are two groups of computational models available, depending on the intended use. The whole-lung models are designed to provide deposition prediction for the whole lung, from the oronasal cavities to the pulmonary region. The whole-lung models are generally semi-empirical and hence provide more reliable results but within the range of parameters used for empirical correlations. The local deposition or computational fluid dynamics (CFD)-based models, on the other hand, utilize comprehensive theoretical and computational approaches but are often limited to upper respiratory tracts. They are based on theoretical principles and are applicable to a wider range of parameters, but less accurate. One of the difficulties with modeling of aerosol deposition in human lung is related to the complexity of the airways geometry and the limited morphometric data available. Another difficulty corresponds to simulation of the realistic physiological conditions of lung environment. Furthermore, complex physical and chemical phenomena associated with dense and multicomponent aerosols complicate the modeling tasks. All of these issues are addressed in this review. The progress made in each area in the last three decades and the challenges ahead are discussed along with some suggestions for future direction. The following subjects are covered in this review: introduction, aerosol deposition mechanisms, elements of a computational model, respiratory-tract geometry models, whole-lung models, CFD based models, cigarette smoke deposition models, and conclusion.

A computer model of lung morphology to analyze SPECT images

Measurement of the spatial distribution of aerosol deposition in human lungs can be performed using single photon emission computed tomography (SPECT). To relate deposition patterns to real lung structures, a computer model of the airway network has been developed. Computer simulations are presented that are compatible with the analysis of SPECT images. Computational techniques that are consistent with clinical procedures are used to analyze airways by type and number within transverse slices of the lung volume. The computer models serve as customized templates, which when analyzed alongside gamma scintigraphy images, can assist in the interpretation of human test data.

Artificial neural network prediction of aerosol deposition in human lungs.

To develop a rapid and reliable method for predicting the pattern of aerosol particle deposition within the human lungs, using artificial neural networks (ANNs). Experimental data from the literature were used to train multi-layer perceptron (MLP) networks to allow for prediction of regional and total aerosol particle deposition patterns in human lungs. These data covered particle sizes in the range 0.05-15 microm and three different breathing patterns (ranging from "quiet" breathing to breathing "under physical work conditions"). Three different MLPs were trained, to provide separate predictions of aerosol particle deposition in the laryngeal, bronchial, and alveolar regions. The total deposition fraction for a given set of breathing conditions was computed simply as the sum of the outputs produced from the corresponding regional deposition MLPs. The ANNs developed are shown to give highly accurate predictions for both regional and total aerosol deposition patterns for all particle sizes and breathing conditions (with errors typically less than 0.04%). We conclude that the current set of ANNs can be used to give good predictions of particle deposition from polydisperse pharmaceutical aerosols generated from breath-actuated dry powder inhalers, nebulizers, and metered dose inhalers with spacers.

Monte Carlo modeling of aerosol deposition in human lungs. Part III: Comparison with experimental data

The Monte Carlo code IDEAL-2 described in Part I [Koblinger and Hofmann, 1990, J. Aerosol Sci. 21, 661–674] has been used to compute total and regional deposition of inhaled aerosols over a wide range of particle diameters. In the present paper, the stochastic lung model has been supplemented by specified oro- and nasopharyngeal regions. Theoretical predictions are compared to the extensive set of experimental data of Heyder et al. [1986, J. Aerosol Sci. 17, 811–825] on total and regional, i.e. extrathoracic, tracheobronchial and alveolar (acinar) deposition for a variety of breathing patterns. To take account of the large individual variations observed in all measurements, intersubject variability has been modeled by scaling up and down the linear dimensions of the lung, while preserving its internal structure.

Monte Carlo modeling of aerosol deposition in human lungs. Part I: Simulation of particle transport in a stochastic lung structure

A stochastic model for the calculation of aerosol deposition in human lungs has been developed. In this model the geometry of the airways along the path of an inhaled particle is selected randomly, whereas deposition probabilities are computed by deterministic formulae. The philosophy of the airway geometry selection, the random walk of particles through this geometry and the methods of aerosol deposition calculation in conductive and respiratory airways during a full breathing cycle are presented. The main features of the Monte Carlo code IDEAL-2, written for the simulation of random walks of particles in a stochastic lung model, are briefly outlined.

Monte Carlo modeling of aerosol deposition in human lungs. Part II: Deposition fractions and their sensitivity to parameter variations

The Monte Carlo code IDEAL-2 described in Part I [(1989) J. Aerosol Sci. 21, 666–674] has been used for the computation of total, regional and differential particle deposition in a stochastic lung structure. The results of these simulations are compared to experimental data and to other theoretical predictions based on deterministic lung models, demonstrating the applicability of our stochastic modeling approach. Compared to more simplistic deterministic models, this stochastic deposition model can supply additional information on the differential distribution throughout the lung and on the variability of the deposition within a given lung segment. A subsequent sensitivity analysis studies the effect of the parameters mainly affecting the resulting deposition pattern.

Fluid flow in a model alveolar sac.

ArticleFluid flow in a model alveolar sac.F F CinkotaiF F CinkotaiPublished Online:01 Aug 1974https://doi.org/10.1152/jappl.1974.37.2.249MoreSectionsPDF (855 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByInfluence of tidal-volume setting, emphysema and ARDS on human alveolar sacs mechanics4 July 2018 | Acta Mechanica Sinica, Vol. 34, No. 5Characterization of Regional and Local Deposition of Inhaled Aerosol Drugs in the Respiratory System by Computational Fluid and Particle Dynamics MethodsJournal of Aerosol Medicine, Vol. 19, No. 3Kinematically irreversible acinar flow: a departure from classical dispersive aerosol transport theoriesF. S. Henry, J. P. Butler, and A. Tsuda1 February 2002 | Journal of Applied Physiology, Vol. 92, No. 2Aerosol probes of lung injury in a 28-wk longitudinal study of mild experimental emphysema in dogsFrank S. Rosenthal1 February 1999 | Journal of Applied Physiology, Vol. 86, No. 2Aerosol Transport and Deposition in the Rhythmically Expanding Pulmonary AcinusJournal of Aerosol Medicine, Vol. 9, No. 3Monte Carlo modeling of aerosol deposition in human lungs. Part II: Deposition fractions and their sensitivity to parameter variationsJournal of Aerosol Science, Vol. 21, No. 5Diffusional deposition of particles in a model alveolusJournal of Aerosol Science, Vol. 9, No. 6 More from this issue > Volume 37Issue 2August 1974Pages 249-51 https://doi.org/10.1152/jappl.1974.37.2.249PubMed4852060History Published online 1 August 1974 Published in print 1 August 1974 Metrics