COMPARISON OF LUNG VASCULAR AND EPITHELIAL PERMEABILITY INDEXES IN THE ADULT RESPIRATORY-DISTRESS SYNDROME

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Abstract
Measurements of pulmonary clearance of inhaled 99mTc-DTPA and transvascular 113mIn-transferrin flux were made in 12 patients with established ARDS and 14 volunteer control subjects (7 smokers and 7 nonsmokers). Smokers had significantly increased 99mTc-DTPA clearance (clearance rate constant, 3.6 .+-. 0.8; mean .+-. SEM) compared with nonsmokers (1.2 .+-. 0.1). All patients with ARDS had increased clearance of 99mTc-DTPA (5.2 .+-. 0.9), but the finding was nonspecific in that increased clearance overlapped with the findings in normal smokers. Protein flux in smokers (protein flux units, 0.0 .+-. 0.2) was similar to that in nonsmokers (0.3 .+-. 0.2). In 9 of the 12 patients with ARDS, protein flux was increased, and as a group (3.2 .+-. 1.0) they differed significantly (p < 0.01) from the combined smoking and nonsmoking control subjects (0.2 .+-. 0.1, n = 14). The parameters of DTPA clearance and transvascular protein flux correlated well in the patients with ARDS (Spearman''s rank correlation = 0.71, p < 0.01). Although 99mTc-DTPA clearance is a sensitive technique in ARDS, a single study in this context does not allow a diagnostic conclusion because of its nonspecificity. Abnormal protein flux appears to be more specific for ARDS but was not a universal finding in the patients studied.