(Chest. 2000;117:246S.)
© 2000
American College of Chest Physicians
Pulmonary Mechanics of Papain Emphysema in Dogs*
Robert E. Hyatt, MD, FCCP;
G. Farkas, PhD and
M. Schroeder
*
From the Mayo Clinic, Rochester, MN. This abstract is funded by HL43865.
Correspondence to: Robert E. Hyatt, MD, FCCP, Pulmonary and Critical Care Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
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Introduction
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 TOP
 Introduction
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Papain by
intratracheal instillation is said to produce a model of human
emphysema. We examined this in 13 dogs receiving 10 to 20 instillations
of papain, dissolved in saline solution, over 11 to 13 months. Four
control dogs received only saline solution. The dogs were lightly
anesthetized during papain delivery and during mechanical studies,
which were done during the baseline period and at sacrifice. Measured
were total lung capacity, forced vital capacity, functional residual
capacity, pulmonary resistance, static compliance and dynamic
compliance, maximal flow at 50% forced vital capacity
(
50), PaO2, and
PaCO2 (see Table 1
).
All lungs were formalin-fixed at a pressure of 30 cm H2O.
Control dogs showed no change and their data are not tabled.
All changes were significant except PaCO2.
Maximal flows were reduced out of proportion to the decrease in static
lung recoil, suggesting the presence of airway disease. Histology
revealed airway atrophy. In sublobar bronchi, airway wall area as a
fraction of total airway area was 0.624 in controls and 0.357 in the
dogs receiving papain. If this atrophy were associated with an increase
in airway compliance, it would further decrease maximal flow according
to the wavespeed mechanism.
Conclusion: Papain emphysema in dogs is not a
perfect model of pure
emphysema.
