Mechanical behavior of excised canine visceral pleura.

A computer-controlled optical electromechanical biaxial test system was employed to study the mechanical response of excised sheets of canine visceral pleura. Three classes of tests were performed: uniform biaxial stretching tests and tests in which the specimen was cyclically stretched along one axis while either the load or dimension was maintained at a prescribed level in the orthogonal direction. The tests were defined completely within the software. Strain was inferred from tracking four particles affixed to the central region of the specimen surface. The visceral pleura was found to behave similarly to other biological soft tissues and required preconditioning to yield repeatable responses. In addition, the visceral pleura appeared to possess in-plane transverse isotropic material symmetry and to exhibit strong in-plane mechanical coupling at lower loads. The data presented herein is sufficient for determination of certain three-dimensional constitutive laws which are essential for further biomechanical analyses of the visceral pleura's role in lung response.