Hysteresis ratio: a measure of the mechanical efficiency of fibrotic and emphysematous hamster lung tissue.

Abstract

In order to evaluate the viscoplastoelastic properties of hamster lungs, we measured a transpulmonary pressure of 25 cmH2O (TLC25(S)), quasistatic lung compliance (CstL(S)), specific compliance (CstL(S)/TLC25(S)), and the hysteresis ratio (HR) in degassed lungs from normal adult (U) and young hamsters (Y), normal lungs with a ligated left main bronchus (L), and lungs from hamsters with elastase-induced emphysema (E) and bleomycin-induced interstitial fibrosis (B). The HR was defined as the area enclosed within the inflation and deflation limbs of the volume-pressure curve, expressed as a percentage of the rectangle enclosing the curve. The lung disease index, a stereologic estimate of the extent of lung disease, was determined from histologic sections of the B group specimens. The L group had significantly diminished CstL(S), TLC25(S), and CstL(S)/TLC25(S) values but normal HR. The Y group also had decreased CstL(S) and TLC25(S) but normal CstL(S)/TLC25(S) and elevated HR. The E group had increased CstL(S...