Surface area-independent assessment of lung microvascular permeability with an amphipathic tracer.
A combination of an amphipathic-indicator-dilution (ID) diffusing tracer 1,4[14C]butanediol (B) and a hydrophilic tracer ([14C]urea) (U) was hypothesized to provide a capillary surface area- (S) independent assessment of lung microvascular permeability (P). We performed ID studies on isolated perfused dog lungs and administered randomly two interventions, increasing P by alloxan infusion and reduction in S by lobar ligation. The ratio of PS product of U (PSU) to that for butanediol (PSB) was sensitive to changes in P yet insensitive to changes in S. We performed ID studies in which the dependence of PSU and PSB on flow, hematocrit, and plasma protein binding were examined. Measurements of PSU and PSB after flow and hematocrit were changed suggested that these factors have no significant independent effects. From ID and in vitro studies we also found that no significant binding of B to plasma proteins (albumin) occurred. We concluded that ID techniques using B and U provide a consistent measure of P, despite changes in S, hematocrit, plasma protein concentration, and recruitment.
Olson
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LE
Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37232.
Pou
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Harris
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D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D002072:Butylene Glycols; D002199:Capillary Permeability / Q000502:physiology*; D004285:Dogs; D005069:Evaluation Studies as Topic; D006400:Hematocrit; D066298:In Vitro Techniques; D007201:Indicator Dilution Techniques; D008833:Microcirculation / Q000502:physiology; D010477:Perfusion; D011652:Pulmonary Circulation / Q000502:physiology*; D012709:Serum Albumin / Q000378:metabolism
D002072:Butylene Glycols; D012709:Serum Albumin; C039681:1,4-butanediol