Beneficial effects of leukocyte-depleted blood and low-potassium dextran solutions on microvascular permeability in preserved porcine lung

Modified Euro-Collins (EC) solution, a crystalloid intracellular-type solut ion, has been commonly used for pulmonary preservation. Several experimenta l studies have shown the advantages of using extracellular colloid-based so lutions. The aim of this study was to compare the quality of preservation o f two extracellular colloid solutions, leukocyte-depleted blood (BL) and lo w-potassium dextran (LPD) solutions, with that of EC solution. Lungs of 22 domestic pigs were flushed and preserved with EC (n = 8), BL (n = 7), or LP D (n = 7) solution. After harvesting, one of the lungs was reperfused immed iately in an ex vivo circuit (control lungs), whereas the contralateral lun g was reperfused after 8 h of cold (4 degrees C) storage (preserved lungs). Besides the lung function parameters (gas exchange, pulmonary hemodynamics and mechanics), the permeability of the endothelial-epithelial barrier was assessed by determining the transferrin leak index (TLI) using a double ra dioisotopic method, by measuring the alveolar/arterial protein concentratio n ratio, and by analyzing histopathologic changes. The functional quality ( oxygenation, airway resistance, dynamic compliance [C-L, dyn]) of both BL a nd LPD lungs was slightly but significantly superior to that of EC lungs. H owever, pulmonary vascular resistance was lower in BL-preserved than in EC- or LPD-preserved lungs. The TLI was increased in EC control and preserved lungs, whereas it was low in BL and LPD control lungs and did not increase after preservation. The alveolar/arterial protein concentration ratio was n ot different between control groups, but was increased fourfold in EC-prese rved compared with BL- or LPD-preserved lungs. Finally, EC-preserved lungs presented a weight gain about twice that of BL- and LPD-preserved lungs. Mo rphologic analysis confirmed these results, because in the EC-preserved lun gs, rupture of alveolar septa and severe alveolar edema and hemorrhage were observed, whereas BL- and LPD-preserved lungs showed a relatively well-pre served structure. The results demonstrate that both BL and LPD flush soluti ons preserve the endothelial-epithelial barrier better than does EC solutio n. Although the quality of preservation is similar, pulmonary vascular resi stance is higher in LPD-preserved than in BL-preserved lungs.