Spreading of exogenous surfactant in an airway

Espinosa, F. F.; Shapiro, Ascher H.; Fredberg, J. J.; Kamm, Roger D.

doi:10.1152/jappl.1993.75.5.2028

Cited by 76 publications

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“…Surface active material instilled into the airways has the capacity to rapidly spread and distribute to the periphery of the lung [147][148][149]. Spreading from the central airways towards the alveoli is promoted by surface tension gradients that drive transport from regions of high surfactant concentration to regions of lower surfactant concentration.…”

Section: Delivery Methods and Dosages For Exogenous Surfactant Therapmentioning

confidence: 99%

Surfactant for Pediatric Acute Lung Injury

Willson¹,

Chess²,

Notter³

2008

Pediatric Clinics of North America

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SynopsisThis article reviews exogenous surfactant therapy and its use in mitigating acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) in infants, children, and adults. Biophysical and animal research documenting surfactant dysfunction in ALI/ARDS is described, and the scientific rationale for treatment with exogenous surfactant is discussed. Major emphasis is on reviewing clinical studies of surfactant therapy in pediatric and adult patients with ALI/ARDS. Particular advantages from surfactant therapy in direct pulmonary forms of these syndromes are described. Also discussed are additional factors affecting the efficacy of exogenous surfactants in ALI/ARDS, including the multifaceted pathology of inflammatory lung injury, the effectiveness of surfactant delivery in injured lungs, and composition-based activity differences among clinical exogenous surfactant preparations.

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Section: Delivery Methods and Dosages For Exogenous Surfactant Therapmentioning

confidence: 99%

Surfactant for Pediatric Acute Lung Injury

Willson¹,

Chess²,

Notter³

2008

Pediatric Clinics of North America

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“…Since Marangoni driven spreading is rather rapid, it is computationally more efficient to introduce a stretched horizontal coordinate, , whose overall length is determined by the leading edge of the surfactant monolayer. For a finite amount of insoluble surfactant spreading in a one-dimensional geometry, a simple scaling analysis 5,28 shows that the leading edge advances in time as L(t)ϭt 1/3 . The following transformations therefore describe the spreading process in stretched coordinates:…”

Section: Base Statementioning

confidence: 99%

The development of transient fingering patterns during the spreading of surfactant coated films

Matar

Troian

1999

Physics of Fluids

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The spontaneous spreading of an insoluble surfactant monolayer on a thin liquid film produces a complex waveform whose time variant shape is strongly influenced by the surface shear stress. This Marangoni stress produces a shocklike front at the leading edge of the spreading monolayer and significant film thinning near the source. For sufficiently thin films or large initial shear stress, digitated structures appear in the wake of the advancing monolayer. These structures funnel the oncoming flow into small arteries that continuously tip-split to produce spectacular dendritic shapes. A previous quasisteady modal analysis has predicted stable flow at asymptotically long times ͓Phys. Fluids A 9, 3645 ͑1997͔͒. A more recent transient analysis has revealed large amplification in the disturbance film thickness at early times ͓O. K. Matar and S. M. Troian, ''Growth of nonmodal transient structures during the spreading of surfactant coated films,'' Phys. Fluids A 10, 1234 ͑1998͔͒. In this paper, we report results of an extended sensitivity analysis which probes two aspects of the flow: the time variant character of the base state and the non-normal character of the disturbance operators. The analysis clearly identifies Marangoni forces as the main source of digitation for both small and large wave number disturbances. Furthermore, initial conditions which increase the initial shear stress or which steepen the shape of the advancing front produce a larger transient response and deeper corrugations in the film. Disturbances applied just ahead of the deposited monolayer rapidly fall behind the advancing front eventually settling in the upstream region where their mobility is hampered. Recent findings confirm that additional forces which promote film thinning can further intensify disturbances ͓O. K. Matar and S. M. Troian, ''Spreading of surfactant monolayer on a thin liquid film: Onset and evolution of digitated structures,'' Chaos 9, 141 ͑1999͒. The transient analysis presented here corroborates our previous results for asymptotic stability but reveals a source for digitation at early times. The energy decomposition lends useful insight into the actual mechanisms preventing efficacious distribution of surfactant.

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“…10,11,16,17 The case ␥ϭ1/2 yields the spreading behavior R(t)ϳt 1/2 , whose base flow solutions 18 and stability characteristics 9 have frequently been discussed in the literature. Equations ͑19͒ and ͑20͒, which describe the film thickness and surface concentration profiles, cannot be integrated exactly for arbitrary values of 1 and 2 .…”

Section: ͑23͒mentioning

confidence: 99%

Linear stability analysis of an insoluble surfactant monolayer spreading on a thin liquid film

Matar

Troian

1997

Physics of Fluids

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Recent experiments by several groups have uncovered a novel fingering instability in the spreading of surface active material on a thin liquid film. The mechanism responsible for this instability is yet to be determined. In an effort to understand this phenomenon and isolate a possible mechanism, we have investigated the linear stability of a coupled set of equations describing the Marangoni spreading of a surfactant monolayer on a thin liquid support. The unperturbed flows, which exhibit simple linear behavior in the film thickness and surfactant concentration, are self-similar solutions of the first kind for spreading in a rectilinear geometry. The solution of the disturbance equations determines that the rectilinear base flows are linearly stable. An energy analysis reveals why these base flows can successfully heal perturbations of all wavenumbers. The details of this analysis suggest, however, a mechanism by which the spreading can be destabilized. We propose how the inclusion of additional forces acting on the surfactant coated spreading film might give rise to regions of adverse mobility gradients known to produce fingering instabilities in other fluid flows.

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Spreading of exogenous surfactant in an airway

Cited by 76 publications

References 0 publications

Surfactant for Pediatric Acute Lung Injury

Surfactant for Pediatric Acute Lung Injury

The development of transient fingering patterns during the spreading of surfactant coated films

Linear stability analysis of an insoluble surfactant monolayer spreading on a thin liquid film

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