AJP - Heart and Circulatory Physiology, Vol 258, Issue 3 754-H758, Copyright © 1990 by American Physiological Society
Pulmonary embolism: emboli and fibrinolysis inhibition in isolated canine lungs
M. I. Townsley, S. A. Barman and A. E. Taylor
Department of Physiology, College of Medicine, University of South Alabama, Mobile 36688.
The effect of fibrinolysis inhibition with tranexamic acid on pulmonary
microvascular permeability during glass bead embolization was investigated
in the isolated lung. Lung lobes from nonheparinized dogs were treated in
vivo with the equivalent of 0.6 g/kg 100 microns glass bead emboli alone,
emboli after tranexamic acid, tranexamic acid alone, or the bead vehicle
alone. After 40-50 min, the lobes were isolated for ex vivo perfusion with
heparinized autologous blood. There were no changes in any parameter over
the 120-min perfusion period. Blood flow at 120 min was decreased after
both emboli alone and emboli with tranexamic acid, reflecting an increase
in vascular resistance compared with the Tween or tranexamic acid controls.
Furthermore, tranexamic acid increased the ratio of pre- to postcapillary
resistance in embolized lobes compared with that after emboli alone or in
the Tween or tranexamic acid controls. The isogravimetric capillary
pressure and the osmotic reflection coefficient were not significantly
decreased by tranexamic acid compared with those after emboli alone;
however, it did result in an increase in the capillary filtration
coefficient compared with that after emboli alone or in the control groups.
We conclude that although fibrinolysis inhibition does not clearly
exacerbate the lung injury seen after emboli, the tranexamic acid-induced
changes in hemodynamics would tend to accelerate edema formation.
