Finite-element analysis of the strain variations in excised lobe of canine lung

The excised right lower lobe of a 10-kg dog's lung was manually inflated to the total capacity and then deflated in a step-wise manner to record the three-dimensional displacements of small metallic markers, which were affixed to the pleural surface, by employing a computer-based biplane roentgen-videographic technique. The temporal and spatial changes of the strains in the lobe during deflation were determined by partitioning of the lobe into a finite number of tetrahedral regions. By taking the implanted markers as the vertices of the tetrahedrons and utilizing their changes in spatial coordinates, finite-element calculations of the strain variations in the lobe were performed. Sample results of strains are presented. It shows that except in the vicinity of one of the implanted markers, the normal strains are generally higher than the shearing strains in the deflating excised lobe.