Pulmonary epithelial permeability in normal individuals and asthmatic patients.

It has been suggested that an increase in lung permeability is the cause for bronchial hyperreactivity in asthma. A method for measuring pulmonary epithelial permeability (PEP) has been developed recently. PEP is estimated by calculating the half-time clearance of inhaled diethylene triamine penta-acetate, labelled with 99m-technetium, with a scintillation counter over the right upper lobe of the lung. Seven normal subjects and 7 patients with stable bronchial asthma had PEP determined. Mean half-time clearance of 99m TC-DTPA in normals and asthmatics were 52.4 minutes and 52.7 minutes respectively. There was no significant difference (p less than 0.5) between these baseline values. Therefore, in patients with stable asthma there is no increase in lung permeability compared with normal subjects.