PULMONARY TRANSVASCULAR FLUID DYNAMICS IN SHEEP DURING HEMORRHAGE

A Malik, H van der Zee, B Lee

Abstract


The effects of hemorrhage on pulmonary hemodynamics
and lung transvascular fluid dynamics were
studied in sheep. We found that 2 hr of hemorrhage
caused a fall in lung lymph flow (p < 0.05 ) and no
sigificant change in lymph protein concentration.
The fall in lymph flow was not due to decreased
vascular surface area since the regional distribution
of pulmonary perfusion was not altered during hemorrhage;
however the decrease in lymph flow was
associated with decrease (p < 0.05 ) in the calculated
pulmonary microvascular pressure. The extravascular
lung water lung content per g blood less dry lung
was increased (p < 0.05 ) in the hemorrhaged sheep
from the control values. Pulmonary edema was not
due to increased lung vascular endothelial permeabiltly
since the net tran vascular protein flux was not
increased. The finding that pulmonary edema occurred
despite the consistent decreases in lymph flow
suggests that edema may be due to hemorrhage-induced
lymphatic "failure" or that edema fluid is
sequestered in spaces (e.g., endothelial cells) where
it cannot be drained by the lymphatics.


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