Quantitative analysis of transpleural flux in the isolated
lung.
Li, Mh, J Hildebrandt, and Mp Hlastala.
Departments of Medicine and of Physiology and Biophysics,
University of Washington, Seattle WA
APStracts 3:0421A, 1996.
In this study, the loss of inert gas through the pleura of an isolated
ventilated and perfused rabbit lung was assessed theoretically and
experimentally. A mathematical model was used to represent an ideal
homogeneous lung placed within a box with gas flow ([square root]b)
surrounding the lung. The alveoli are assumed to be ventilated with
room air ([square root]A), and perfused at constant flow (_)
containing inert gases (x) with various [lambda]px (perfusate/air
partition coefficients). The ratio of transpleural flux of gas
([square root]plx) to its total delivery to the lung via pulmonary
artery ([square root]a) representing fractional losses across the
pleura, can be shown to depend on four dimensionless ratios. These
are: 1) [lambda]px, 2) [square root]A/_, the ratio of alveolar
ventilation to perfusion, 3) Dplx/ ([square root]Abg), the ratio of
the pleural diffusing capacity to the conductance of the alveolar
ventilation, and 4) ([square root]b)/([square root]A), the ratio of
extrapleural (box) ventilation to the alveolar ventilation.
Experiments were performed in isolated perfused and ventilated rabbit
lungs. The perfusate was a buffer solution containing six dissolved
inert gases covering the entire 10-fold range of lpx used in the
multiple inert gas elimination technique. Steady state inert gas
concentrations were measured in the pulmonary arterial perfusate,
pulmonary venous effluent, exhaled gas and box effluent gas. The
experimental data could be described satisfactorily by the single
compartment model. It is concluded that a simple theoretical model is
a useful tool for predicting transpleural flux from isolated lung
preparations, with known ventilation and perfusion, for inert gases
within a wide range of [lambda].
Received 31 January 1996; accepted in final form 26 August 1996.
APS Manuscript Number A109-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 September 1996