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Experimental study of flow fields in an airway closure model

  • S. BIAN (a1), C.-F. TAI (a1), D. HALPERN (a2), Y. ZHENG (a1) and J. B. GROTBERG (a1)...


The liquid lining in small human airways can become unstable and form liquid plugs that close off the airways. Bench-top experiments have been performed in a glass capillary tube as a model airway to study the airway instability and the flow-induced stresses on the airway walls. A microscale particle image velocimetry system is used to visualize quantitatively the flow fields during the dynamic process of airway closure. An annular film is formed by injecting low-viscosity Si-oil into the glycerol-filled capillary tube. The viscosity ratio between these two fluids is similar to that between water and air. The thickness of the film varies with the infusion rate of the core fluid, which is controlled by a syringe pump. After a uniform film is formed, the syringe pump is shut off so that the core flow speed is close to zero during closure. Instantaneous velocity fields in the annular film at various stages of airway closure are computed from the images and analysed. The wall shear stress at the instant when a liquid plug forms is found to be approximately one order of magnitude higher than the exponential growth period before closure. Within the short time span of the closure process, there are large wall shear stress fluctuations. Furthermore, dramatic velocity changes in the film flow during closure indicate a steep normal stress gradient on the airway wall. The experimental results show that the wall shear stress during closure can be high enough to injure airway epithelial cells. An airway that experiences closure and reopening cyclically during breathing could be injured from fluid forces during both phases of the cycle (i.e. inspiration and expiration).


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Baker, C. S., Evans, T. W., Randle, B. J. & Haslam, P. L. 1999 Damage to surfactant-specific protein in acute respiratory distress syndrome. Lancet 353 (9160), 12321237.
Bilek, A. M., Dee, K. C. & Gaver, D. P. III 2003 Mechanisms of surface-tension-induced epithelial cell damage in a model of pulmonary airway reopening. J. Appl. Physiol. 94 (2), 770783.
Bretherton, F. P. 1961 The motion of long bubbles in tubes. J. Fluid Mech. 10 (2), 166188.
Campana, D. M., Di Paolo, J. & Saita, F. A. 2004 A 2-D model of Rayleigh instability in capillary tubes: surfactant effects. Intl J. Multiphase Flow 30 (5), 431454.
Cassidy, K. J., Halpern, D., Ressler, B. G., & Grotberg, J. B. 1999 Surfactant effects in model airway closure experiments. J. Appl. Physiol. 87 (1), 415427.
Dargaville, P. A., South, M. & McDougall, P. N. 1996 Surfactant abnormalities in infants with severe viral bronchiolitis. Arch. Dis. Child. 75 (2), 133136.
Everett, D. H. & Haynes, J. M. 1972 Model studies of capillary condensation. Part 1. Cylindrical pore model with zero contact angle. J. Colloid Interface Sci. 38 (1), 125137.
Fairbrother, F. & Stubbs, A. E. 1935 Studies in electro-endosmosis. Part VI. The ‘bubble-tube’ method of measurement. J. Chem. Soc. 1, 527529.
Fujioka, H. & Grotberg, J. B. 2004 Steady propagation of a liquid plug in a two-dimensional channel. J. Biomech. Engng Trans. Asme 126 (5), 567577.
Fujioka, H. & Grotberg, J. B. 2005 The steady propagation of a surfactant-laden liquid plug in a two-dimensional channel. Phys. Fluids 17 (8), 082102.
Fujioka, H., Takayama, S. & Grotberg, J. B. 2008 Unsteady propagation of a liquid plug in a liquid-lined straight tube. Phys. Fluids 20 (6), 062104.
Gauglitz, P. A. & Radke, C. J. 1988 An extended equation for liquid-film break up in cylindrical capillaries. Chem. Engng Sci. 43 (7), 14571465.
Ghadiali, S. N. & Gaver, D. P. III 2008 Biomechanics of liquid–epithelium interactions in pulmonary airways. Respir. Physiol. Neurobiol. 163 (1–3), 232243.
Goerke, J. & Clements, J. A. 1986 Alveolar Surface Tension and Lung Surfactant. American Physiology Society.
Goldsmith, H. L. & Mason, S. G. 1963 Flow of suspensions through tubes. Part 2. Single large bubbles. J. Colloid Sci. 18 (3), 237261.
Greaves, I. A., Hildebrandt, J. & Hoppin, J. F. G. 1986 Handbook of Physiology. The Respiratory System. Mechanics of Breathing. American Physiology Society.
Green, F. H. Y., Schurch, S., Desanctis, G. T., Wallace, J. A., Cheng, S. & Prior, M. 1991 Effects of hydrogen sulfide exposure on surface properties of lung surfactant. J. Appl. Physiol. 70 (5), 19431949.
Griese, M., Essl, R., Schmidt, R., Rietschel, E., Ratjen, F., Ballmann, M. & Paul, K. 2004 Pulmonary surfactant, lung function, and endobronchial inflammation in cystic fibrosis. Am. J. Respir. Crit. Care Med. 170 (9), 10001005.
Guerin, C., LeMasson, S., DeVarax, R., MilicEmili, J. & Fournier, G. 1997 Small airway closure and positive end-expiratory pressure in mechanically ventilated patients with chronic obstructive pulmonary disease. Am. J. Respir. Crit. Care Med. 155 (6), 19491956.
Gunther, A., Siebert, C., Schmidt, R., Ziegler, S., Grimminger, F., Yabut, M., Temmesfeld, B., Walmrath, D., Morr, H. & Seeger, W. 1996 Surfactant alterations in severe pneumonia, acute respiratory distress syndrome, and cardiogenic lung edema. Am. J. Respir. Crit. Care Med. 153 (1), 176184.
Halpern, D. & Gaver, D. P. III 1994 Boundary-element analysis of the time-dependent motion of a semi-infinite bubble in a channel. J. Comput. Phys. 115 (2), 366375.
Halpern, D. & Grotberg, J. B. 1992 Fluid-elastic instabilities of liquid-lined flexible tubes. J. Fluid Mech. 244, 615632.
Halpern, D. & Grotberg, J. B. 1993 Surfactant effects on fluid-elastic instabilities of liquid-lined flexible tubes: a model of airway closure. J. Biomech. Engng Trans. Asme 115 (3), 271277.
Halpern, D., Jensen, O. E. & Grotberg, J. B. 1998 A theoretical study of surfactant and liquid delivery into the lung. J. Appl. Physiol. 85 (1), 333352.
Hammond, P. S. 1983 Nonlinear adjustment of a thin annular film of viscous-fluid surrounding a thread of another within a circular cylindrical pipe. J. Fluid Mech. 137, 363384.
Heil, M., Hazel, A. L. & Smith, J. A. 2008 The mechanics of airway closure. Respir. Physiol. Neurobiol. 163 (1–3), 214221.
Hof, V. I., Gehr, P., Gerber, V., Lee, M. M. & Schurch, S. 1997 In vivo determination of surface tension in the horse trachea and in vitro model studies. Respir. Physiol. 109 (1), 8193.
Huh, D., Fujioka, H., Tung, Y.-C., Futai, N., Paine, III, R., Grotberg, J. B. & Takayama, S. 2007 Acoustically detectable cellular-level lung injury induced by fluid mechanical stresses in microfluidic airway systems. Proc. Natl Acad. Sci. USA 104 (48), 1888618891.
Kamm, R. D. & Schroter, R. C. 1989 Is airway closure caused by a liquid-film instability. Respir. Physiol. 75 (2), 141156.
Kay, S. S., Bilek, A. M., Dee, K. C. & Gaver, D. P. III 2004 Pressure gradient, not exposure duration, determines the extent of epithelial cell damage in a model of pulmonary airway reopening. J. Appl. Physiol. 97 (1), 269276.
Lee, M. M., Schurch, S., Roth, S. H., Jiang, X., Cheng, S., Bjarnason, S. & Green, F. H. 1995 Effects of acid aerosol exposure of the surface properties of airway mucus. Exp. Lung Res. 21 (6), 835851.
Macklem, P. T., Proctor, D. F. & Hogg, J. C. 1970 Stability of peripheral airways. Respir. Physiol. 8 (2), 191203.
Muscedere, J. G., Mullen, J. B., Gan, K. & Slutsky, A. S. 1994 Tidal ventilation at low airway pressures can augment lung injury. Am. J. Respir. Crit. Care Med. 149 (5), 13271334.
Piirila, P. & Sovijarvi, A. R. A. 1995 Crackles: recording, analysis and clinical significance. Eur. Respir. J. 8 (12), 21392148.
Rayleigh, L. 1892 On the instability of cylindrical fluid surfaces. Phil. Mag. 34, 177180.
Reinelt, D. A. & Saffman, P. G. 1985 The penetration of a finger into a viscous fluid in a channel and tube. Siam J. Sci. Stat. Comput. 6 (3), 542561.
Taskar, V., John, J., Evander, E., Robertson, B. & Jonson, B. 1997 Surfactant dysfunction makes lungs vulnerable to repetitive collapse and reexpansion. Am. J. Respir. Crit. Care Med. 155 (1), 313320.
Taylor, G. I. 1961 Deposition of a viscous fluid on the wall of a tube. J. Fluid Mech. 10 (2), 161165.
t Veen, J. C. C., Beekman, A. J., Bel, E. H. & Sterk, P. J. 2000 Recurrent exacerbations in severe asthma are associated with enhanced airway closure during stable episodes. Am. J. Respir. Crit. Care Med. 161 (6), 19021906.
Zheng, Y., Fujioka, H., Bian, S., Torisawa, Y., Huh, D., Takayama, S. & Grotberg, J. B. 2009 Liquid plug propagation in flexible microchannels: a small airway model. Phys. Fluids 21 (7), 071903.
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Experimental study of flow fields in an airway closure model

  • S. BIAN (a1), C.-F. TAI (a1), D. HALPERN (a2), Y. ZHENG (a1) and J. B. GROTBERG (a1)...


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