Combined Effect of Low-dose Nitric Oxide Gas Inhalation with Partial Liquid Ventilation on Hemodynamics, Pulmonary Function, and Gas Exchange in Acute Lung Injury of Newborn Piglets

Choi, Chang Won; Hwang, Jong Hee; Chang, Yun Sil; Park, Won Soon

doi:10.3346/jkms.2003.18.6.813

Cited by 2 publications

(1 citation statement)

References 28 publications

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“…During the airway-reopening process, pulmonary epithelial cells may be damaged by mechanical stresses associated with fluid motion 5,6 and plug rupture. 7 Externally, liquid is instilled into the pulmonary airways in some medical treatments such as surfactant replacement therapy ͑SRT͒, [8][9][10][11][12] partial liquid ventilation ͑PLV͒, [13][14][15][16][17][18][19] and drug delivery. [20][21][22][23][24][25][26][27][28][29] The formation of a liquid plug in the trachea, before inspiration, is important in creating a more uniform liquid distribution throughout the lung.…”

Section: Introductionmentioning

confidence: 99%

Unsteady propagation of a liquid plug in a liquid-lined straight tube

2008

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This paper considers the propagation of a liquid plug driven by a constant pressure within a rigid axisymmetric tube whose inner surface is coated by a thin liquid film. The Navier-Stokes equations are solved using the finite-volume method and the SIMPLEST algorithm. The effects of precursor film thickness, initial plug length, pressure drop across the plug, and constant surface tension on the plug behavior and tube wall mechanical stresses are investigated. As a plug propagates through a liquid-lined tube, the plug gains liquid from the leading front film, and it deposits liquid into the trailing film. If the trailing film is thicker (thinner) than the precursor film, the plug volume decreases (increases) as it propagates. For a decreasing volume, eventually the plug ruptures. Under a specific set of conditions, the trailing film thickness equals the precursor film thickness, which leads to steady state results. The plug speed decreases as the precursor film thins because the resistance to the moving front meniscus increases. As the pressure drop across the plug decreases, the plug speed decreases resulting in thinning of the trailing film. As the plug length becomes longer, the viscous resistance in the plug core region increases, which slows the plug and causes the trailing film to become even thinner. The magnitude of the pressure and shear stress at the tube inner wall is maximum in the front meniscus region, and it increases with a thinner precursor film. As the surface tension increases, the plug propagation speed decreases, the strength of the wall pressure in the front meniscus region increases, and the pressure gradient around the peak pressure becomes steeper.

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Section: Introductionmentioning

confidence: 99%

Unsteady propagation of a liquid plug in a liquid-lined straight tube

2008

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The steady propagation of a surfactant-laden liquid plug in a two-dimensional channel

Fujioka

Grotberg

2005

Physics of Fluids

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In this study, we investigate the steady propagation of a liquid plug in a two-dimensional channel lined by a uniform, thin liquid film. The liquid contains soluble surfactant that can exist both in the bulk fluid and on the air-liquid interface. The Navier-Stokes equations with free-surface boundary conditions and the surfactant transport equations are solved using a finite volume numerical scheme. The adsorption/desorption process of the surfactant is modeled based on pulmonary surfactant properties. As the plug propagates, the front meniscus sweeps preexisting interfacial surfactant from the precursor film, and the surfactant accumulates on the front meniscus interface. As the front meniscus converges on the precursor film from the region where the interfacial surfactant concentration is maximized, the Marangoni stress opposes the flow. In this region, the Marangoni stress results in nearly zero surface velocity, which causes the precursor film thickness near the meniscus to be thicker than the leading film thickness. Since the peaks of wall pressure and wall shear stress occur due to narrowing of the film thickness, the observed increase of the minimum film thickness weakens these stresses. In the thicker film region, however, the drag forces increase due to an increase in the surfactant concentration. This causes the overall pressure drop across the plug to increase as a result of the increasing surfactant concentration. A recirculation flow forms inside the plug core and is skewed toward the rear meniscus as the Reynolds number increases. When no surfactant exists, the recirculation flow is in contact with both the front and the rear interfaces. As the surfactant concentration increases, the Marangoni stress begins to rigidify the front interface and forces the recirculation flow away from the front interface. Subsequently, the recirculation flow is directed away from the rear interface in a manner similar to that for the front interface. When the plug length is shorter, this change in recirculation pattern occurs at a smaller surfactant concentration.

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Combined Effect of Low-dose Nitric Oxide Gas Inhalation with Partial Liquid Ventilation on Hemodynamics, Pulmonary Function, and Gas Exchange in Acute Lung Injury of Newborn Piglets

Cited by 2 publications

References 28 publications

Unsteady propagation of a liquid plug in a liquid-lined straight tube

Unsteady propagation of a liquid plug in a liquid-lined straight tube

The steady propagation of a surfactant-laden liquid plug in a two-dimensional channel

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