Heterogeneous structure and surface tension effects on mechanical response in pulmonary acinus: A finite element analysis

Kenichiro Koshiyama, Keisuke Nishimoto, Satoshi Ii, Toshihiro Sera, Shigeo Wada

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Background: The pulmonary acinus is a dead-end microstructure that consists of ducts and alveoli. High-resolution micro-CT imaging has recently provided detailed anatomical information of a complete in vivo acinus, but relating its mechanical response with its detailed acinar structure remains challenging. This study aimed to investigate the mechanical response of acinar tissue in a whole acinus for static inflation using computational approaches. Methods: We performed finite element analysis of a whole acinus for static inflation. The acinar structure model was generated based on micro-CT images of an intact acinus. A continuum mechanics model of the lung parenchyma was used for acinar tissue material model, and surface tension effects were explicitly included. An anisotropic mechanical field analysis based on a stretch tensor was combined with a curvature-based local structure analysis. Findings: The airspace of the acinus exhibited nonspherical deformation as a result of the anisotropic deformation of acinar tissue. A strain hotspot occurred at the ridge-shaped region caused by a rod-like deformation of acinar tissue on the ridge. The local structure becomes bowl-shaped for inflation and, without surface tension effects, the surface of the bowl-shaped region primarily experiences isotropic deformation. Surface tension effects suppressed the increase in airspace volume and inner surface area, while facilitating anisotropic deformation on the alveolar surface. Interpretation: In the lungs, the heterogeneous acinar structure and surface tension induce anisotropic deformation at the acinar and alveolar scales. Further research is needed on structural variation of acini, inter-acini connectivity, or dynamic behavior to understand multiscale lung mechanics.

Original languageEnglish
Pages (from-to)32-39
Number of pages8
JournalClinical Biomechanics
Publication statusPublished - Jun 2019

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Orthopedics and Sports Medicine


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