Regional pulmonary blood volume in patients with abnormal blood pressure or flow in the pulmonary circulation

We studied the effects of a chronic increase in flow and ofchronic hypertension on regional pulmonary blood volume andextravascular lung density (lung tissue and interstitial waterper unit thoracic volume) in one group of patients with intracardiac,left-to-right shunt and in another group with Eisenmenger'ssyndrome or primary pulmonary hypertension. We used positroncomputerized tomography to measure regional lung density (transmissionscans) and blood volume (labelling with ¹¹CO). The distribution of pulmonary blood volume was more uniformin patients with a chronic increase in pulmonary blood flowthan in normal subjects. There were also indications of an absoluteincrease in intrapulmonary blood volume. In patients with chronicpulmonary arterial hypertension, the regional distribution ofblood volume was abnormally uniform, but there were no indicationsof substantial abnormalities in overall intrapulmonary bloodvolume.