P5151

         Am J Respir Crit Care Med 2000 Sep;162(3 Pt 1):1052-7

        Lung volume reduction surgery does not improve diaphragmatic contractile

        properties or atrophy in hamsters with elastase-induced emphysema.

        Marchand E, De Leyn P, Gayan-Ramirez G, Palecek F, de Bock V, Dom R,

        Decramer M.

        Respiratory Muscle Research Unit, Laboratory of Pneumology and

        Respiratory Division, Thoracic Surgery Division, and Neuropathology

        Department, University Hospitals, Katholieke Universiteit Leuven,

        Leuven, Belgium.

        It is claimed that lung volume reduction surgery (LVRS) improves

        inspiratory muscle function. As diaphragm structure and function are not

        directly appraisable in patients, we studied the effects of LVRS on the

        diaphragm in vitro contractile properties and morphology in hamsters

        with elastase-induced emphysema. Four months after intratracheal

        instillation of elastase (40 U/100 g), hamsters underwent either

        bilateral LVRS (LVRS, n = 11) or a sham operation (SHAM, n = 8). Four

        animals died during the perioperative period in LVRS (n = 7). Hamsters

        instilled with saline served as control (CTL, n = 8). Animals were

        studied at the age of 9 mo. LVRS was associated with a significant 25%

        decrease in functional residual capacity compared to SHAM (p < 0.05).

        Compared with CTL, LVRS and SHAM showed a significant 18% and 14%

        reduction in diaphragm mass, respectively (p = 0.02). LVRS had a

        significantly decreased twitch tension compared to CTL and SHAM (p <

        0.01). Both LVRS and SHAM showed increased resistance to muscle fatigue

        compared with CTL. The histochemical analysis revealed a significant

        shift from type IIx/b toward type IIa fibers in LVRS and SHAM compared

        with CTL. In conclusion, emphysema is associated with functional

        adaptations but LVRS does not appear to beneficially alter the diaphragm

        contractile and morphological characteristics in hamsters with

        elastase-induced emphysema.