Mechanism of lobar alveolar pressure decline during forced
deflation in canine regional emphysema.
Mink, S. N.
Sections of Respiratory Diseases and Critical Care Medicine,
University of Manitoba, Winnipeg, Manitoba, R3E- OZ3, Canada
APStracts 3:0473A, 1996.
A canine model of unilobar papain- induced emphysema was used to
examine the extent to which differences in alveolar pressures (Palv)
would develop between an emphysematous right lower lobe (RLL) and
normal left lower lobe (LLL) during forced vital capacity (VCtot)
deflation. RLL and LLL Palv were measured by the alveolar capsule
technique. During forced deflation, Palv and lobar flows were
determined between 95% and 20% VCtot. A choke-point common to both
lower lobes was observed at > 40% VCtot. The results showed
that deflation compliance (C) was altered for the RLL, such that
below 90% lobar VC, CRLL was > CLLL, while above 90% lobar VC,
CRLL was < CLLL. At 95% and 90% VCtot, the initial RLL Palv
decline was greater than that for the LLL (p<.05). However,
large differences in Palv were prevented because of the effect of
interdependence of regional expiratory flow (IREF). IREF caused a
relative in decrease in RLL flows and increase in LLL flows which
limited Palv differences. Between 80 to 50% VCtot, as CRLL became
greater than CLLL, and because of the initial effect of IREF, PalvRLL
nearly equal to PalvLLL. At
Received 28 September 1995; accepted in final form 30 September
1996.
APS Manuscript Number A1046-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996