Pulmonary edema: a CT study of regional changes in lung density following oleic acid injury.

Transmission computed tomography (CT) was used to study the global and regional density changes in the dog lung associated with oleic acid induced lung injury. The same level of the lower thorax was scanned (5 s/scan) during suspended ventilation at functional residual capacity prior to and after oleic acid infusion (0.05 ml/kg) into the right atrium. The first signs of edema were usually seen within 15 to 30 min after oleic acid infusion and consisted of patchy areas of increased density primarily in the peripheral and dependent zones. Mean CT density (Hounsfield units + 1,000) of lung cross sections from five dogs was 198 +/- 9 (SEM) during base line; density significantly (p less than 0.05) increased to 243 +/- 14 30 min after infusion and reached an apparent plateau of 294 +/- 31 75 min after oleic acid infusion. Thermal-dye dilution measurements indicated that extravascular lung water increased by 3.8 ml/kg from base line to 75 min after oleic acid infusion.