Biomedical Engineering Reference
In-Depth Information
6
Conclusions
The adhesive contact element proposed here can reproduce the hysteresis loop
observed in the collapse and recruitment of a group of alveoli, in agreement with
the order of magnitude of the involved physical measures. Recruitment is triggered
at higher pressures than the collapse, which is the same asymmetry observed
experimentally. However it does not reproduce the viscous dissipative aspects of
lung dynamics, such as liquid flow, variation of surfactant concentration and tissue
viscoelasticity.
This finite element simulations can be applied to large populations of alveoli,
which would allow a more realistic structural analysis. Another big advantage of
this element is that its parameters can be adjusted with experimental measurements.
However the adhesion magnitude on the surface of the alveoli still has to be
measured by tribological experiments. The relationship between the surfactant, the
liquid film and the surface of the epithelial cell membrane also needs to be better
understood.
Even without reliable parameters for a more accurate assessment for the estima-
tion of the intensity of the adhesion forces, this contact element can already simulate
aspects not found in the literature.
Acknowledgements
This work was supported by the National Counsel of Technological and
Scientific Development (“Conselho Nacional de Desenvolvimento Cientfico e Tecnolgico” -
CNPq) 135262/2007-0.
References
1. Moore KL, Dalley AF (2001) Anatomia orientada para a clınica, 4th edn. Guanabara Koogan,
Rio de Janeiro
2. Fung YC (1975b) Dose the surface tension make the lung inherenthly unstable? Circ Res
37:497
3. Fung YC (1975a) Stress, deformation, and atelectasis of the lung. Circ Res 37:481
4. Bassingthwaighte JB (2000) Strategies for the physiome project. Ann Biomed Eng 28:1043
5. Hoppin FG, Lee GC, Dawson SV (1975) Properties of lung parenchyma in distortion. J Appl
Physiol 39(5):742
6. Vawter DL, Fung YC, West JB (1978) Elasticity of excised dog lung parenchyma. J Appl
Physiol 45(2):261
7. Zeng YJ, Yager D, Fung YC (1987) Measurement of mechanical properties of the human lung
parenchyma. J Biomech Eng 109:169
8. Fung YC (1993) Biomechanics: mechanical properties of living tissues, 2nd edn. Springer,
New York
9. Hansen JE, Ampaya EP, Bryant GH, Navin JJ (1975) The branching pattern of airways and air
spaces of a single human terminal bronchiole. J Appl Physiol 38(6):983
10. Hansen JE, Ampaya EP (1975) Human air space shapes, sizes, areas, and volumes. J Appl
Physiol 38(6):990
11. Dale PJ, Matthews FL, Schroter RC (1980) Finite element analysis of lung alveolus. J Biomech
13:865
