Pulmonary microvascular reflection coefficients estimated with a
modified lymphatic washdown technique.
Drake, R. E., S. Dhother, and J. C. Gabel.
Departements of Anesthesiology, The University of Texas Medical
School, Houston, Texas and The UCLA School of Medicine, Los Angeles,
California
APStracts 3:0319H, 1996.
Many investigators have used the lymphatic protein washdown technique
to estimate the pulmonary microvascular membrane reflection
coefficient to protein (s[delta]). With that technique, the
investigator causes a high microvascular filtration rate, then
estimates s[delta] from the lymph and plasma protein concentrations.
However the lymph may contain protein washed from the lung tissue and
the tissue protein may cause investigators to underestimate s[delta].
Plasma protein osmotic pressure (Pc) may cause investigators to
underestimate s[delta] because Pc opposes fluid filtration. To
minimize the effect of Pc, we decreased Pc to 5.6 +/- 1.1 mmHg in 5
anesthetized sheep. We increased the microvascular filtration rate by
increasing pulmonary microvascular pressure to 22 +/- 3 mmHg. Then we
tagged plasma protein with Evans blue dye and estmated s[delta] from
the lymph and plasma dye concentrations. Because tissue protein was
not tagged, it did not interfere with our s[delta] estimate. Our
s[delta] estimate (0.79 +/- 0.08) was much higher than previous
estimates in anesthetized animals.
Received 28 May 1996; accepted in final form 22 July 1996.
APS Manuscript Number H474-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996