Respiratory work in elastase treated hamsters

Biomechanical adaptations of the diaphragm in the hamster model of emphysem a are similar to those observed in skeletal muscle with exercise training. The aim of this study was to evaluate whether the dynamic pressure-volume ( PV) work of breathing in hamsters with elastase-induced emphysema may contr ibute to these adaptations. PV work in elastase treated animals was compare d to healthy controls. The studies were performed in adult hamsters 14-16 m onths following intratracheal administration of elastase (elastase treated group, ET) or saline (control group, CTL). Airway and esophageal pressures and air flows were measured during spontaneous breathing in anesthetized, s upine animals. Pulmonary work (WL) was computed from transpulmonary pressur es and airflows. Functional residual capacity (FRC) and total lung capacity (TLC; defined as volume at 25 cmH(2)O) in ET were increased 2 and 1.8 time s, respectively, compared with CTL. Averaged tidal volume (VT) and inspirat ory flows were comparable between groups. Total work of breathing (WT) norm alized per mi VT was not significantly affected with elastase treatment but the pulmonary elastance work (WE) was significantly less in ET animals tha n controls (0.88 +/- 0.61 g cm(-2) vs. 1.63 +/- 0.32). Pulmonary resistive work was not significantly different between ET and CTL animals. These resu lts suggest that biomechanical adaptations of the diaphragm observed in ET hamsters are caused by mechanisms other than the changes in dynamic mechani cal properties of the lung following elastase treatment. (C) 1998 Elsevier Science B.V. All rights reserved.