Subpleural pulmonary microvascular pressures in the dog lung .
Haworth, Steven T., David A. Rickaby, John H. Linehan, and Christopher
A. Dawson.
Biomedical Engineering Department, Marquette University, Milwaukee,
WI 53233, Department of Physiology, Medical College of Wisconsin,
Milwaukee, WI 53226, Department of Veterans Affairs; Zablocki VAMC;,
Milwaukee, WI 53295
APStracts 2:0124A, 1995.
The reported values for the pressure difference between lobar artery
and subpleural arteriole and between subpleural venule and lobar vein
as a fraction of the total artery to vein pressure drop across the
dog lung have varied considerably. We carried out the present study
to provide an additional set of measurements and to determine whether
it is likely that differences in venous pressure or transpulmonary
pressure between studies might make a substantial contribution to
variations between studies. We measured the lobar artery pressure,
Pa, to subpleural arteriole (22 - 60 [mu]m diameter) pressure, Pma,
to subpleural venule (30 - 80 [mu]m diameter) pressure, Pmv, to lobar
vein pressure, Pv, distribution over a range of alveolar pressures
(2.5 to 13.1 Torr), and venous pressures, (0 to 24.2 Torr), in
isolated dog lung lobes, using the micropuncture servo-null
technique. On average, near Functional Residual Capacity (PA = 3
Torr) and venous pressure equal to alveolar pressure, Pa_ Pma : Pma_
Pmv : Pmv_ Pv was 37 % : 30 % : 33%. Under zone 3 conditions, there
was a small positive correlation between the fractional Pa to Pma
pressure difference and PA and Pv, but dependence of the Pmv to Pv
fraction on PA and Pv was not consistent. The overall effects of PA
and Pv on the fractional pressure drops were not sufficient to
account for differences between previous studies. Under zone 2
conditions as the venous pressure was varied, the changes in Pmv were
nearly equal to the changes in Pv, while Pma was relatively
insensitive to Pv. Thus, the zone 2 results were consistent with a
capillary location for the flow limiting segment under zone 2
conditions.
Received 9 November 1994; accepted in final form 15 March 1995.
APS Manuscript Number A1153-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 28 March 1995.