Elastic constants of trapped lung parenchyma.

Isolated dog lobes were maximally trapped with air, and their parenchymal elastic properties were measured at the trapped volume. Indentation tests were performed on the surface of the lobes, followed by uniaxial and torsion tests on excised pieces of parenchyma. Similar values for Young's modulus were obtained from the indentation and uniaxial tests. The values for the shear modulus from the torison tests also were consistent with Young's modulus measured by the other procedures. The indentation test provided an accurate estimate of Young's modulus or the shear modulus for trapped lobes, and the results suggest that it is a valid method for estimating these constants in nontrapped lobes.