Distribution of Regional Density and Vascular Permeability in the Adult Respiratory Distress Syndrome

Abstract

Although recent X-ray computed tomography (CT) data show that ventral-dorsal gradients in density are common in the adult respiratory distress syndrome (ARDS), we hypothesized that the ventral-dorsal gradient of pulmonary vascular permeability would be evenly distributed in patients with ARDS. We tested this hypothesis by analyzing previously reported data (Am Rev Respir Dis 1991; 143:150–154) obtained by the nuclear medicine imaging technique of positron emission tomography (PET). Measurements of regional lung density (LD), extravascular density (EVD), and the pulmonary transcapillary escape rate (PTCER; an index of vascular permeability) were obtained in eight patients with ARDS and in 10 normal subjects. The data from four contiguous tomographic slices were organized into 20 anatomically oriented “bins” from the ventral (Bin #1) to dorsal (Bin #20) position. Mean overall LD, ERD, and PTCER were all significantly higher (p < 0.05) in the ARDS patients than in normal subjects. Regression slopes of LD ver...