Wong F, Liu P, Allidina Y, Blendis L
Department of Medicine, Toronto Hospital, University of Toronto, Ontario, Canada.
Hepatology. 1996 May;23(5):1141-7. doi: 10.1053/jhep.1996.v23.pm0008621146.
The status of the central blood volume in cirrhosis is controversial. A combination of sodium restriction and upright posture, which redistributes intravascular volume to dependent parts of the body should further aggravate a contracted central blood volume reduction. The aim of this study was to determine the effect of upright posture and sodium restriction on central blood volume (CBV) in preascitic cirrhotic patients, compared with controls. Eight male, preascitic, alcoholic cirrhotic subjects and eight healthy male controls were studied while on a 20-mmol/d sodium diet. Measurements of CBV by radionuclide angiography, and neurohumoral factors were performed on day 7 in both supine and erect positions and cardiac output and systemic vascular resistance (SVR) was calculated. Sodium restriction resulted in less weight loss in the cirrhotic patients (P = .03), with significantly lower plasma renin activity (P = .001). Similar central blood volumes and systemic hemodynamics were observed in both groups in the supine posture. In contrast to the cirrhotic patients, in the control subjects, upright posture resulted in a significant reduction in cardiac output (P = .002) and increase in SVR (P = .005), associated with a decrease in all blood volumes which were significantly less than in the cirrhotic patients. Mean arterial pressure was maintained in both groups in both postures. In conclusion, with sodium restriction, preascitic cirrhotic patients have less intravascular volume contraction than control patients. Erect posture results in redistribution of this relatively expanded intravascular volume to the CBV. Therefore, a low-sodium diet can be safely administered in preascitic cirrhotic patients.
肝硬化患者中心血容量的状况存在争议。钠限制和直立姿势相结合会将血管内容量重新分配到身体的下垂部位，这应该会进一步加重中心血容量的收缩性降低。本研究的目的是确定与对照组相比，直立姿势和钠限制对腹水前期肝硬化患者中心血容量（CBV）的影响。对8名男性腹水前期酒精性肝硬化受试者和8名健康男性对照者进行了研究，他们采用每日20 mmol的钠饮食。在第7天，分别在仰卧位和直立位通过放射性核素血管造影测量CBV，并检测神经体液因子，同时计算心输出量和全身血管阻力（SVR）。钠限制使肝硬化患者体重减轻较少（P = .03），血浆肾素活性显著降低（P = .001）。两组在仰卧位时观察到相似的中心血容量和全身血流动力学。与肝硬化患者不同，在对照组中，直立姿势导致心输出量显著降低（P = .002），SVR升高（P = .005），同时所有血容量均减少，且减少幅度明显小于肝硬化患者。两组在两种姿势下平均动脉压均维持稳定。总之，在钠限制情况下，腹水前期肝硬化患者的血管内容量收缩程度低于对照患者。直立姿势导致这种相对扩张的血管内容量重新分配至CBV。因此，腹水前期肝硬化患者可以安全地采用低钠饮食。
