scholarly journals The influence of surfactant on the propagation of a semi-infinite bubble through a liquid-filled compliant channel

2012 ◽  
Vol 698 ◽  
pp. 125-159 ◽  
Author(s):  
David Halpern ◽  
Donald P. Gaver III
Keyword(s):  
Surface Tension ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Mechanical Stimulus ◽  
Airway Epithelial Cells ◽  
Bulk Concentration ◽  
Airway Reopening ◽  
Biological Studies ◽  
Soluble Surfactant

AbstractWe investigate the influence of a soluble surfactant on the steady-state motion of a finger of air through a compliant channel. This study provides a basic model from which to understand the fluid–structure interactions and physicochemical hydrodynamics of pulmonary airway reopening. Airway closure occurs in lung diseases such as respiratory distress syndrome and acute respiratory distress syndrome as a result of fluid accumulation and surfactant insufficiency. This results in ‘compliant collapse’ with the airway walls buckled and held in apposition by a liquid occlusion that blocks the passage of air. Airway reopening is essential to the recovery of adequate ventilation, but has been associated with ventilator-induced lung injury because of the exposure of airway epithelial cells to large interfacial flow-induced pressure gradients. Surfactant replacement is helpful in modulating this deleterious mechanical stimulus, but is limited in its effectiveness owing to slow surfactant adsorption. We investigate the effect of surfactant on micro-scale models of reopening by computationally modelling the steady two-dimensional motion of a semi-infinite bubble propagating through a liquid-filled compliant channel doped with soluble surfactant. Many dimensionless parameters affect reopening, but we primarily investigate how the reopening pressure ${p}_{b} $ depends upon the capillary number $\mathit{Ca}$ (the ratio of viscous to surface tension forces), the adsorption depth parameter $\lambda $ (a bulk concentration parameter) and the bulk Péclet number ${\mathit{Pe}}_{b} $ (the ratio of bulk convection to diffusion). These studies demonstrate a dependence of ${p}_{b} $ on $\lambda $, and suggest that a critical bulk concentration must be exceeded to operate as a low-surface-tension system. Normal and tangential stress gradients remain largely unaffected by physicochemical interactions – for this reason, further biological studies are suggested that will clarify the role of wall flexibility and surfactant on the protection of the lung from atelectrauma.

scholarly journals Sulforhodamine B and exogenous surfactant effects on alveolar surface tension under acute respiratory distress syndrome conditions

2020 ◽  
Vol 129 (6) ◽  
pp. 1505-1513 ◽  
Author(s):  
Tam L. Nguyen ◽  
Carrie E. Perlman
Keyword(s):  
Surface Tension ◽  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Exogenous Surfactant ◽  
Sulforhodamine B ◽  
Isolated Lungs ◽  
Surfactant Effects ◽  
Alveolar Surface

In the acute respiratory distress syndrome (ARDS), lowering surface tension, T, should reduce ventilation injury, yet exogenous surfactant has not reduced mortality. We show with direct T determination in isolated lungs that substances suggested to elevate T in ARDS indeed raise T, and exogenous surfactant reduces T. Further, we extend our previous finding that sulforhodamine B (SRB) reduces T below normal in healthy lungs and show that SRB, too, reduces T under ARDS conditions.

scholarly journals Respiratory and Systemic Effects of LASSBio596 Plus Surfactant in Experimental Acute Respiratory Distress Syndrome

2016 ◽  
Vol 38 (2) ◽  
pp. 821-835 ◽  
Author(s):  
Johnatas Dutra Silva ◽  
Gisele Pena de Oliveira ◽  
Cynthia dos Santos Samary ◽  
Carla Cristina Araujo ◽  
Gisele de Araujo Padilha ◽  
...  
Keyword(s):  
Surface Tension ◽  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Cecal Ligation ◽  
Exogenous Surfactant ◽  
Experimental Sepsis ◽  
Apoptosis Protein ◽  
Anti Inflammatory

Background/Aims: Exogenous surfactant has been proposed as adjunctive therapy for acute respiratory distress syndrome (ARDS), but it is inactivated by different factors present in the alveolar space. We hypothesized that co-administration of LASSBio596, a molecule with significant anti-inflammatory properties, and exogenous surfactant could reduce lung inflammation, thus enabling the surfactant to reduce edema and improve lung function, in experimental ARDS. Methods: ARDS was induced by cecal ligation and puncture surgery in BALB/c mice. A sham-operated group was used as control (CTRL). After surgery (6 hours), CTRL and ARDS animals were assigned to receive: (1) sterile saline solution; (2) LASSBio596; (3) exogenous surfactant or (4) LASSBio596 plus exogenous surfactant (n = 22/group). Results: Regardless of exogenous surfactant administration, LASSBio596 improved survival rate and reduced collagen fiber content, total number of cells and neutrophils in PLF and blood, cell apoptosis, protein content in BALF, and urea and creatinine levels. LASSBio596 plus surfactant yielded all of the aforementioned beneficial effects, as well as increased BALF lipid content and reduced surface tension. Conclusion: LASSBio596 exhibited major anti-inflammatory and anti-fibrogenic effects in experimental sepsis-induced ARDS. Its association with surfactant may provide further advantages, potentially by reducing surface tension.

scholarly journals Very low surfactant protein C contents in newborn Belgian White and Blue calves with respiratory distress syndrome

2000 ◽  
Vol 351 (3) ◽  
pp. 779-787 ◽  
Author(s):  
Fabien DANLOIS ◽  
Shahparak ZALTASH ◽  
Jan JOHANSSON ◽  
Bengt ROBERTSON ◽  
Henk P. HAAGSMAN ◽  
...  
Keyword(s):  
Surface Tension ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Protein C ◽  
Distress Syndrome ◽  
Surfactant Protein ◽  
Healthy Controls ◽  
Surfactant Protein C ◽  
Organic Extracts ◽  
Newborn Calves

We have studied a respiratory distress syndrome (RDS) occurring in newborn calves of the Belgian White and Blue (BWB) breed that represents the large majority of beef cattle in Belgium. Pulmonary surfactant isolated from 14 BWB newborn calves that died from RDS and from 7 healthy controls was analysed for composition and surface activity. An extremely low content or, in some instances, an absence of surfactant protein C (SP-C) was detected in the RDS samples by Western blotting and differential amino acid analysis [0.03±0.01% (w/w) relative to total phospholipids, compared with 0.39±0.06% for healthy controls (means±S.E.M., P < 0.001)]. The contents of surfactant protein B (SP-B) were similar in RDS and control samples. The crude surfactant samples isolated from RDS calves had higher ratios of total protein to total phospholipid, altered phospholipid profiles and lower SP-A contents. Both crude and organic extracts of RDS surfactant samples showed increased dynamic surface tension compared with healthy controls when evaluated with a pulsating-bubble surfactometer. The addition of purified SP-C to organic extracts of RDS surfactant samples lowered surface tension. Strongly decreased levels of mature SP-C associated with fatal RDS and altered surface activity in vitro have, to the best of our knowledge, not been previously reported. The mechanisms underlying RDS and the decrease in SP-C in BWB calves remain to be established.

scholarly journals Liquid Ventilation

1996 ◽  
Vol 3 (6) ◽  
pp. 370-372 ◽  
Author(s):  
Peter N Cox
Keyword(s):  
Carbon Dioxide ◽  
Surface Tension ◽  
Gas Exchange ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Dependent Lung ◽  
Liquid Ventilation ◽  
Protective Strategies ◽  
Over Time

There has been a recent explosion of interest in the use of liquid ventilation. Over time humans have lost the physiological attributes necessary for respiration in water. However, perfluorocarbons have high solubilities for oxygen and carbon dioxide, as well as a low surface tension. These characteristics allow them to be used as a medium to assist gas exchange and recruit atelectatic-dependent lung zones in respiratory distress syndrome. Current trials may prove perfluorocarbon to be a useful adjunct in lung protective strategies in respiratory distress syndrome.

The Effect of Vibrations on Surfactant Dynamics in the Neonate

2009 ◽  
Author(s):  
Prasika I. Reddy ◽  
Ahmed M. Al-Jumaily ◽  
David E. White
Keyword(s):  
Surface Tension ◽  
Numerical Model ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Dynamic Behavior ◽  
Premature Infants ◽  
Distress Syndrome ◽  
Breathing Frequency ◽  
Air Liquid Interface

Respiratory distress syndrome (RDS) is the leading cause of mortality in premature infants, arising primarily from a lack of surfactant in the lung. The dynamic behavior of surface tension in the alveoli is modelled using a numerical model and compared with in-vitro experimentation on a pulsating bubble surfactometer (PBS). The effect of adding superimposed oscillations (from 10–70 Hz) on the breathing frequency is investigated in both the model and experiment. The model and experiment show encouraging comparisons and suggest that the mechanisms of improving surfactant function with oscillatory treatments lie with the increase of diffusion and adsorption of surfactant molecules to the air-liquid interface in the alveoli.

scholarly journals Sulforhodamine B and exogenous surfactant effects on alveolar surface tension under acute respiratory distress syndrome conditions

2020 ◽  
Author(s):  
Tam L. Nguyen ◽  
Carrie E. Perlman
Keyword(s):  
Surface Tension ◽  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Exogenous Surfactant ◽  
Sulforhodamine B ◽  
Surfactant Activity ◽  
Isolated Lungs ◽  
Alveolar Surface

AbstractIn the acute respiratory distress syndrome (ARDS), alveolar surface tension, T, may be elevated. Elevated T should increase ventilation-induced lung injury. Exogenous surfactant therapy, intended to lower T, has not reduced mortality. Sulforhodamine B (SRB) might, alternatively, be employed to lower T. We test whether substances suspected of elevating T in ARDS raise T in the lungs and test the abilities of exogenous surfactant and SRB to reduce T. In isolated rat lungs, we micropuncture a surface alveolus and instill a solution of a purported T-raising substance: control saline, cell debris, secretory phospholipase A2 (sPLA2), acid or mucins. We test each substance alone; with albumin, to model proteinaceous edema liquid; with albumin and exogenous surfactant; or with albumin and SRB. We determine T in situ in the lungs by combining servo-nulling pressure measurement with confocal microscopy, and applying the Laplace relation. With control saline, albumin does not alter T, additional surfactant raises T and additional SRB lowers T. The experimental substances, without or with albumin, raise T. Excepting under aspiration conditions, addition of surfactant or SRB lowers T. Exogenous surfactant activity is concentration and ventilation dependent. Sulforhodamine B, which could be delivered intravascularly, holds promise as an alternative therapeutic.New and NoteworthyIn the acute respiratory distress syndrome (ARDS), lowering surface tension, T, should reduce ventilation injury yet exogenous surfactant has not reduced mortality. We show with direct T-determination in isolated lungs that substances suggested to elevate T in ARDS indeed raise T, and exogenous surfactant reduces T. Further, we extend our previous finding that sulforhodamine B (SRB) reduces T below normal in healthy lungs and show that SRB, too, reduces T under ARDS conditions.

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