Distribution of regional volumes and ventilation in excised canine lobes

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Abstract
A linear elasticity solution for the gravitational deformation of excised lungs was obtained. The accuracy of the solution was examined by comparing predicted and measured displacements of markers glued to the surface of canine lower lobes. The equations describing the strains in a lobe were used to predict the distribution of regional volumes and the slope of phase III (S3) of a single-breath O2 (SBO2) test. The analysis predicted a negative S3. S3 was positive in the 5 lobes tested, suggesting that factors other than gravity were responsible for the observed pattern of ventilation. In SBO2 tests repeated with increasing delays at end inflation, S3 progressively decreased, became negative and was eventually abolished. The equations predicted well the most negative observed S3. Continuum mechanics can be used to describe the gravitational deformation of lungs and the resulting effect on ventilation distribution.