The lung permeability index: A feasible measurement of pulmonary capillary permeability

SummaryBackgroundWe performed this study to determine the pulmonary capillary permeability (PCP) measuring radiolabeled human serum albumin leakage into the lung. The objective was to use PCP to differentiate between cardiogenic and non-cardiogenic pulmonary edema etiologies.MethodsWe conducted this study in 10 patients admitted to the intensive care unit who had recently developed bilateral pulmonary infiltrates and required hemodynamic monitoring. In these patients we determined the association among the lung permeability index, cardiac output, pulmonary capillary wedge pressure, myocardial performance index, and the protein content of the bronchoalveolar lavage as expressed by bronchoalveolar lavage (BAL) total protein and BAL-to-serum protein ratio. Twenty mCi of technetium-labeled albumin was injected and measure in the heart and the lung at 10 and 180 min post-injection. Lung and heart uptake ratios as well as the lung permeability index were calculated.ResultsWe found a good correlation between the lung permeability index and both the myocardial performance index (cardiac output/pulmonary capillary wedge pressure) and the total protein content of the bronchoalveolar lavage fluid.ConclusionThe lung permeability index is a feasible, noninvasive estimation of the pulmonary capillary permeability.