Asymmetric droplets vs. axisymmetric toroids: liquid-gas interfaces in small pulmonary airways.
Lindsley-WG; Collicott-SH; Frazer-DG
Biomedical Engineering: New Challenges for the Future. 2004 Annual Fall Meeting of the Biomedical Engineering Society (BMES), October 13-16, 2004, Philadelphia, Pennsylvania. Landover, MD: Biomedical Engineering Society (BMES), 2004 Oct; :1
Airway closure and gas trapping can occur during lung deflation and inflation when fluid menisci form across the lumina of respiratory passageways. Previous analyses of the behavior of liquid in airways have generally assumed that the airway is completely wetted or that the contact angle of the liquid-gas interface with the airway wall is 0 degrees, and thus that the airway fluid forms an axisymmetric surface. However, some investigators have suggested that liquid in the airways is discontinuous and that contact angles can be as high as 67 degrees. In this study we considered the characteristics of constant curvature surfaces that could form a stable liquid-gas interface in a cylindrical airway. Our analysis suggests that, for small liquid volumes, asymmetric droplets are more likely to form than axisymmetric toroids. In addition, if the fluid contact angle is greater than 13 degrees, asymmetric droplets can sustain larger liquid volumes than axisymmetric toroids before collapsing to form menisci. If a meniscus forms in an airway and then ruptures, it is more likely to form a single droplet rather than a toroid. At larger volumes, asymmetric droplets also generate higher transmural pressures than do axisymmetric toroids, which could help resolve fluid from the airways and reduce the possibility of meniscus formation. These results suggest that (1) fluid formations other than axisymmetric toroids can occur in the airways; and (2) the analysis of the behavior of fluids and the development of liquid menisci within the lungs should include the potential role of asymmetric droplets.
Airway-obstruction; Pulmonary-system; Pulmonary-function; Lung-function; Lung; Fluid-mechanics; Fluids
Abstract; Conference/Symposia Proceedings
Work Environment and Workforce: Mixed Exposures
Biomedical Engineering: New Challenges for the Future. 2004 Annual Fall Meeting of the Biomedical Engineering Society (BMES), October 13-16, 2004, Philadelphia, Pennsylvania