A rat lung model of instilled liquid transport in the pulmonary airways

2001 ◽  
Vol 90 (5) ◽  
pp. 1955-1967 ◽  
Author(s):  
K. J. Cassidy ◽  
J. L. Bull ◽  
M. R. Glucksberg ◽  
C. A. Dawson ◽  
S. T. Haworth ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Image Intensifier ◽  
Lung Model ◽  
Exogenous Surfactant ◽  
Upper Airways ◽  
Liquid Distribution ◽  
Liquid Plug ◽  
Transport Dynamics ◽  
Pulmonary Airways ◽  
Forced Air

When a liquid is instilled in the pulmonary airways during medical therapy, the method of instillation affects the liquid distribution throughout the lung. To investigate the fluid transport dynamics, exogenous surfactant (Survanta) mixed with a radiopaque tracer is instilled into tracheae of vertical, excised rat lungs (ventilation 40 breaths/min, 4 ml tidal volume). Two methods are compared: For case A, the liquid drains by gravity into the upper airways followed by inspiration; for case B, the liquid initially forms a plug in the trachea, followed by inspiration. Experiments are continuously recorded using a microfocal X-ray source and an image-intensifier, charge-coupled device image train. Video images recorded at 30 images/s are digitized and analyzed. Transport dynamics during the first few breaths are quantified statistically and follow trends for liquid plug propagation theory. A plug of liquid driven by forced air can reach alveolar regions within the first few breaths. Homogeneity of distribution measured at end inspiration for several breaths demonstrates that case B is twice as homogeneous as case A. The formation of a liquid plug in the trachea, before inspiration, is important in creating a more uniform liquid distribution throughout the lungs.

scholarly journals Effect of ventilation rate on instilled surfactant distribution in the pulmonary airways of rats

2004 ◽  
Vol 97 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Joseph C. Anderson ◽  
Robert C. Molthen ◽  
Christopher A. Dawson ◽  
Steve T. Haworth ◽  
Joseph L. Bull ◽  
...  
Keyword(s):  
Image Intensifier ◽  
Ventilation Rate ◽  
Exogenous Surfactant ◽  
Partial Liquid Ventilation ◽  
Liquid Distribution ◽  
Liquid Plug ◽  
Transport Dynamics ◽  
Surfactant Replacement Therapy ◽  
Pulmonary Airways ◽  
Uniform Liquid

Liquid can be instilled into the pulmonary airways during medical procedures such as surfactant replacement therapy, partial liquid ventilation, and pulmonary drug delivery. For all cases, understanding the dynamics of liquid distribution in the lung will increase the efficacy of treatment. A recently developed imaging technique for the study of real-time liquid transport dynamics in the pulmonary airways was used to investigate the effect of respiratory rate on the distribution of an instilled liquid, surfactant, in a rat lung. Twelve excised rat lungs were suspended vertically, and a single bolus (0.05 ml) of exogenous surfactant (Survanta, Ross Laboratories, Columbus, OH) mixed with radiopaque tracer was instilled as a plug into the trachea. The lungs were ventilated with a 4-ml tidal volume for 20 breaths at one of two respiratory rates: 20 or 60 breaths/min. The motion of radiodense surfactant was imaged at 30 frames/s with a microfocal X-ray source and an image intensifier. Dynamics of surfactant distribution were quantified for each image by use of distribution statistics and a homogeneity index. We found that the liquid distribution depended on the time to liquid plug rupture, which depends on ventilation rate. At 20 breaths/min, liquid was localized in the gravity-dependent region of the lung. At 60 breaths/min, the liquid coated the airways, providing a more vertically uniform liquid distribution.

scholarly journals Radiation Dosimetry of Inhaled Radioactive Aerosols: CFPD and MCNP Transport Simulations of Radionuclides in the Lung

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Khaled Talaat ◽  
Jinxiang Xi ◽  
Phoenix Baldez ◽  
Adam Hecht
Keyword(s):  
Monte Carlo ◽  
Respiratory Tract ◽  
Radiation Dosimetry ◽  
Energy Deposition ◽  
Radiation Transport ◽  
The Body ◽  
Lung Model ◽  
Whole Body ◽  
Upper Airways ◽  
Radioactive Aerosols

AbstractDespite extensive efforts in studying radioactive aerosols, including the transmission of radionuclides in different chemical matrices throughout the body, the internal organ-specific radiation dose due to inhaled radioactive aerosols has largely relied on experimental deposition data and simplified human phantoms. Computational fluid-particle dynamics (CFPD) has proven to be a reliable tool in characterizing aerosol transport in the upper airways, while Monte Carlo based radiation codes allow accurate simulation of radiation transport. The objective of this study is to numerically assess the radiation dosimetry due to particles decaying in the respiratory tract from environmental radioactive exposures by coupling CFPD with Monte Carlo N-Particle code, version 6 (MCNP6). A physiologically realistic mouth-lung model extending to the bifurcation generation G9 was used to simulate airflow and particle transport within the respiratory tract. Polydisperse aerosols with different distributions were considered, and deposition distribution of the inhaled aerosols on the internal airway walls was quantified. The deposition mapping of radioactive aerosols was then registered to the respiratory tract of an image-based whole-body adult male model (VIP-Man) to simulate radiation transport and energy deposition. Computer codes were developed for geometry visualization, spatial normalization, and source card definition in MCNP6. Spatial distributions of internal radiation dosimetry were compared for different radionuclides (131I, 134,137Cs, 90Sr-90Y, 103Ru and 239,240Pu) in terms of the radiation fluence, energy deposition density, and dose per decay.

Flow limitation and wheezes in a constant flow and volume lung preparation

1988 ◽  
Vol 64 (1) ◽  
pp. 17-20 ◽  
Author(s):  
N. Gavriely ◽  
J. B. Grotberg
Keyword(s):  
Lung Model ◽  
Acoustic Properties ◽  
Flow Limitation ◽  
Suction Pressure ◽  
Constant Flow ◽  
Additional Increase ◽  
Suction Pump ◽  
Pleural Surface ◽  
Pulmonary Airways ◽  
Lung Preparation

To facilitate the study of respiratory wheezes in an animal lung model, an isovolume, constant-flow excised dog lung preparation was developed. Dog lungs were inflated to 26 +/- 4 cmH2O and coated with layers of epoxy glue and polyester compound. A rigid shell 2 mm thick was obtained around the entire pleural surface and the extra-pulmonary airways. The adhesive forces between the pleura and the shell were strong enough to hold the lung distended after the inflation pressure was removed. Holes 2 mm diam were drilled through the shell over one of the lung lobes in an array, 4 cm across. The holes penetrated the pleural surface, so that constant flow could be maintained in the expiratory direction by activating a suction pump connected to the trachea. Downstream suction pressure and flow rate were measured with a mercury manometer and a rotameter, respectively. Sounds were recorded by a small (0.6 cm OD) microphone inserted into the trachea. When suction pressure was increased, flow initially increased to 31 +/- 3 l/min. Further increase of suction pressure caused only very slight additional increase in flow (i.e., flow limitation). During this plateau of flow, a pure tone was generated with acoustic properties similar to respiratory wheezes. Both the flow plateau and the wheezing sounds could be eliminated by freezing the lungs. It is concluded that wheezing sounds were associated with flow limitation in this preparation. It is suggested that the stable acoustic properties obtained by this preparation may become useful in the analysis of mechanisms of wheezing lung sounds generation.

scholarly journals A Stream Function Approach to Optical Flow with Applications to Fluid Transport Dynamics

PAMM ◽  
2011 ◽  
Vol 11 (1) ◽  
pp. 855-856 ◽  
Author(s):  
Aaron Luttman ◽  
Erik Bollt ◽  
Ranil Basnayake ◽  
Sean Kramer
Keyword(s):  
Optical Flow ◽  
Stream Function ◽  
Fluid Transport ◽  
Function Approach ◽  
Transport Dynamics

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

2020 ◽  
Vol 196 ◽  
pp. 105613
Author(s):  
R. Agujetas ◽  
R. Barrio-Perotti ◽  
C. Ferrera ◽  
A. Pandal-Blanco ◽  
D.K. Walters ◽  
...  
Keyword(s):  
Lung Model ◽  
Upper Airways ◽  
Real Geometry ◽  
Lower Airways

Computational Modeling of Surfactant-Laden Liquid Plug Propagation in Capillary Tubes

2012 ◽  
Author(s):  
Metin Muradoglu ◽  
Ufuk Olgac
Keyword(s):  
Replacement Therapy ◽  
Pulmonary Surfactant ◽  
Distress Syndrome ◽  
Standard Treatment ◽  
Exogenous Surfactant ◽  
Liquid Plug ◽  
Front Tracking Method ◽  
Surfactant Replacement ◽  
Surfactant Replacement Therapy ◽  
Shed Light

Pulmonary surfactant is of essential importance in reducing the surface tension on the liquid film that coats the inner surface of the airways and thus making the lung more compliant. Surfactant-deficiency may result in respiratory distress syndrome (RDS), which is especially common in prematurely born neonates. Surfactant replacement therapy (SRT) is a standard treatment, in which a liquid plug with exogenous surfactant is instilled in the trachea, which subsequently propagates by inspiration and spreads the exogenous surfactant to the airways. The efficacy of the treatment depends on various parameters such as the size of the liquid plug, inspiration frequency and the physical properties of the exogenous surfactant. Unsteady simulations are performed to study surfactant-laden liquid plug propagation using finite difference/front-tracking method in order to shed light on the surfactant replacement therapy.

Propagation of an Air Finger Into a Fluid Filled Bifurcation

2010 ◽  
Author(s):  
Benjamin L. Vaughan ◽  
James B. Grotberg
Keyword(s):  
Numerical Model ◽  
Viscous Fluid ◽  
Pressure Difference ◽  
Respiratory Diseases ◽  
Critical Pressure ◽  
Distress Syndrome ◽  
The Other ◽  
Liquid Plug ◽  
Pulmonary Airways ◽  
Single Branch

The occlusion of pulmonary airways can be caused by many respiratory diseases such as respiratory distress syndrome. It is believed that these occluded airways are reopened by the propagation of an air finger. The mechanics of airway reopening have been studied in-depth for an individual airway [1,2] without considering the frequent branching of pulmonary airways. The presence of a bifurcation leads to the question of whether the propagating air finger will clear both branches of the airway or will propagate through a single branch, leaving the other branch occluded. The propagation of a finite length liquid plug through a fixed bifurcation has been studied experimentally [3, 4]. We wish to develop a numerical model for the propagation of an air finger through bifurcating channel filled with a viscous fluid. In this model, the air finger is driven by a pressure difference between the parent channel and the two daughter branches. The presence of an additional pressure difference between the two branches can cause unsymmetrical splitting of the air finger and, above a critical pressure difference, prevent the clearance of both branches.

scholarly journals The Role of Airway Shunt Elastance on the Compartmentalization of Respiratory System Impedance

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Jason H. T. Bates
Keyword(s):  
Respiratory System ◽  
Upper Airway ◽  
Inverse Model ◽  
Tree Model ◽  
Upper Airways ◽  
Peripheral Airways ◽  
Pulmonary Airways ◽  
Peripheral Airway ◽  
In Series ◽  
Airway Tree

An inverse model consisting of two elastic compartments connected in series and served by two airway conduits has recently been fit to measurements of respiratory impedance in obese subjects. Increases in the resistance of the distal conduit of the model with increasing body mass index have been linked to peripheral airway compression by mass loading of the chest wall. Nevertheless, how the two compartments and conduits of this simple model map onto the vastly more complicated structure of an actual lung remain unclear. To investigate this issue, we developed a multiscale branching airway tree model of the respiratory system that predicts realistic input impedance spectra between 5 and 20 Hz with only four free parameters. We use this model to study how the finite elastances of the conducting airway tree and the proximal upper airways affect impedance between 5 and 20 Hz. We show that progressive constriction of the peripheral airways causes impedance to appear to arise from two compartments connected in series, with the proximal compartment being a reflection of the elastance of upper airway structures proximal to the tracheal entrance and the lower compartment reflecting the pulmonary airways and tissues. We thus conclude that while this simple inverse model allows evaluation of overall respiratory system impedance between 5 and 20 Hz in the presence of upper airway shunting, it does not allow the separate contributions of central versus peripheral pulmonary airways to be resolved.

Micro and Nanofluidic Transport Using Advanced Photonic Devices

2006 ◽  
Author(s):  
Allen Yang ◽  
Sudeep Mandal ◽  
David Erickson
Keyword(s):  
Electromagnetic Fields ◽  
Fluid Transport ◽  
Optoelectronic Devices ◽  
Photonic Devices ◽  
Particle Trapping ◽  
Numerical Work ◽  
Transport Dynamics ◽  
Field Gradients ◽  
Fundamental Understanding ◽  
Optical Transport

A number of emerging "optofluidic[1]" technologies exploit the exploitation of the high optical intensities and field gradients present in nanophotonic and optoelectronic devices to accomplish tunable particle trapping and ultrafine propulsion. While well developed theory for exists for freespace optical transport techniques (e.g. optical tweezing), there exists a considerable lack of fundamental understanding of the coupling of the electromagnetic fields and fluid/transport dynamics within these nano-environment. In this work we will present our recent theoretical, experimental and numerical work geared towards developing a better understanding and exploitation of these systems.

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