The status of the central blood volume in cirrhosis is bution of this increased circulatory volume, in particcontroversial. A combination of sodium restriction and ular, to the intrathoracic compartment, that is, the upright posture, which redistributes intravascular volcentral blood volume (CBV) [6][7][8] is still a matter of conume to dependent parts of the body should further agtroversy. The different findings reported may be begravate a contracted central blood volume reduction. cause of differences in methodology and dietary so-The aim of this study was to determine the effect of updium intake. Irrespective of the distribution of the right posture and sodium restriction on central blood circulatory volume, the volume expansion in cirrhovolume (CBV) in preascitic cirrhotic patients, compared sis has been attributed to sodium retention, the with controls. Eight male, preascitic, alcoholic cirrhotic pathogenesis of which is still controversial, but sinusubjects and eight healthy male controls were studied soidal portal hypertension, 9,10 hepatic dysfuncwhile on a 20-mmol/d sodium diet. Measurements of CBV by radionuclide angiography, and neurohumoral factors tion, 11,12 and systemic arterial vasodilatation 13,14 were performed on day 7 in both supine and erect posihave all been implicated. More recently, a sodium tions and cardiac output and systemic vascular resishandling abnormality in preascitic cirrhosis has been tance (SVR) was calculated. Sodium restriction resulted suggested to be due to decreased renal sodium excrein less weight loss in the cirrhotic patients (P ร
.03), tion during upright posture. 15 The resultant volume with significantly lower plasma renin activity (P ร
.001). expansion in turn contributes to and perpetuates the Similar central blood volumes and systemic hemodyportal hypertension. Plasma volume contraction, namics were observed in both groups in the supine poswhether with sodium restriction, 16 or with diuretture. In contrast to the cirrhotic patients, in the control ics 17,18 has been associated with a decrease in portal subjects, upright posture resulted in a significant reducpressure. Furthermore, sodium restriction has been tion in cardiac output (P ร
.002) and increase in SVR (P shown to improve the hyperdynamic circulation in an ร
.005), associated with a decrease in all blood volumes which were significantly less than in the cirrhotic pa-experimental model of cirrhosis, 16 as well as in hutients. Mean arterial pressure was maintained in both man subjects who were also on spironolactone. 19 groups in both postures. In conclusion, with sodium re-CBV, the stimulus to volume receptors and barorestriction, preascitic cirrhotic patients have less intravasceptors, and hence central to the maintenance of syscular volume contraction than control patients. Erect temic hemodynamics, 20 should also be reduced in reposture results in redistribution of this relatively exsponse to sodium restriction as part of the plasma panded intravascular volume to the CBV. Therefore, a volume contraction. Therefore, sodium restriction in low-sodium diet can be safely administered in preascitic the presence of a decreased baseline CBV would pocirrhotic patients. (HEPATOLOGY 1996;23:1141-1147.) tentially have a deleterious effect. Upright posture in normal healthy controls leads to redistribution of Cardiovascular abnormalities are well recognized in plasma volume to the dependent parts of the body, 21 cirrhosis. These include systemic arterial vasodilatathereby reducing the CBV. Therefore, upright postion, a hyperdynamic circulation, 1,2 and increased total ture together with sodium restriction in cirrhotic pacirculatory volume. [3][4][5] However, the question of distritients with a reduced CBV 7 could potentially be hazardous. On the other hand, upright posture has been associated with sodium retention and volume expan-Abbreviations: CBV, central blood volume; NE, norepinephrine; PRA, plasma renin activity; SVR, systemic vascular resistance. sion with normal sodium intake in cirrhosis. 15,22 From the Departments of 1 Medicine and 2 Nuclear Cardiology, The Toronto Therefore, sodium restriction could reduce the so-