Journal of Applied Physiology, Vol 63, Issue 4 1387-1395, Copyright © 1987 by American Physiological Society
Effects of arterial ligation and embolization on pulmonary vascular pressure distribution
M. L. Tod, M. L. McGeady, P. Rock and J. T. Sylvester
Department of Medicine, Johns Hopkins Medical Institutions at Francis Scott Key Medical Center, Baltimore, Maryland 21224.
The effects of embolization on the longitudinal distribution of pulmonary
vascular pressures with respect to vascular compliance were determined by
the vascular inflow and outflow occlusion technique in isolated
blood-perfused pig lungs treated with papaverine to prevent vasomotor
responses. Embolization with microspheres having mean diameters of 75, 200,
and 550 microns and with barrier beads (2 X 3 X 3.5 mm) significantly
increased the pressure gradient across the relatively compliant middle
region (delta Pm) without increasing the gradients across the relatively
noncompliant regions on the arterial (delta Pa) or venous (delta Pv) ends
of the vasculature. In contrast ligation of several lobar arteries caused
delta Pa to increase from 0.9 +/- 0.3 to 5.9 +/- 1.1 mmHg but did not
change delta Pm or delta Pv. Assuming that delta Pa and delta Pv measured
by vascular occlusion result from cessation of flow through resistances,
these data suggest that in isolated pig lungs the vessels at the boundary
between the arterial and middle regions defined by the occlusion technique
are arteries greater than 2-3 mm diam and smaller than lobar arteries.
