Lung elastic recoil during breathing at increased lung volume. Rodarte, Joseph R., Gassan Noredin, Charles Miller, Vito Brusasco and Riccardo Pellegrino, (with Technical Assistance Of Todd M. Officer). 1Department of Medicine - Pulmonary Section, Baylor College of Medicine, Houston, Texas 77030, 2Fisiopatalogia Respiratoria, Ospedale A. Carle, 12100 Cuneo, Italy. 3Dipertimento di Scienze Motorie e Riabilitetive, Universit[grave]a d_gli Studi di Genova, 16132 Genova, Italy.
APStracts 6:0269A, 1999.
During dynamic hyperinflation with induced bronchoconstriction, there is a reduction in lung elastic recoil at constant lung volume (Pellegrino JAP 81:964-975, 1996). In the present study lung elastic recoil at control end inspiration was measured before and after voluntary increases in mean lung volume achieved by one tidal volume increase in functional residual capacity (FRC) with constant tidal volume and doubling tidal volume with constant FRC in normal subjects in a volume displacement plethysmograph. Lung elastic recoil at control end inspiration was significantly decreased by about 10% within four breaths of increasing FRC. When tidal volume was doubled, the decrease in computed lung recoil at control end inspiration was not significant. Since voluntary increases of lung volume should not produce airway closure, we conclude that stress relaxation was responsible for the decrease in lung recoil. 

Received 5 March 1999; accepted in final form 3 June 1999.
APS Manuscript Number A169-9.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1999 The American Physiological Society.
Published in APStracts on 25 June 1999