The size of central vascular space in cirrhosis; position-induced redistribution of central blood volume

Abstract

The aim of this study was to determine the relative size of central blood volume (CBV) and its redistribution after taking up the erect posture. In 19 patients with alcoholic or posthepatitic cirrhosis and 11 healthy controls the whole-body imaging of the 99mTc-labeled red blood cell equilibrium distribution was performed and geometrical mean of counts in the anterior and posterior projection was used for calculations. In addition, thoraco-abdominal scintigrams were obtained in supine and erect postures. Regions of interest were outlined within the cardiopulmonary, splanchnic and renal area. Contribution of CBV to the total blood radioactivity was similar in both groups (21.6 versus 21.8%). By contrast, the relative size of the splanchnic vascular bed was greater in cirrhotic patients than in controls (31.6 versus 25.4%, P<0.005). In cirrhotic patients taking up the erect posture was accompanied by impaired redistribution of CBV to the noncentral vascular bed. In conclusion, this study demonstrates that in cirrhosis the blood is preferentially pooled in splanchnic circulation, but this phenomenon does not affect the size of CBV. CBV is not reduced in the erect posture either, since its gravitational shift to the noncentral vascular compartment is limited.