Piccoli Antonio
Department of Medical and Surgical Sciences, Nephrology Clinic, University of Padova, Padova, Italy.
Contrib Nephrol. 2010;164:143-152. doi: 10.1159/000313727. Epub 2010 Apr 20.
Adequacy of body fluid volume improves short- and long-term outcomes inpatients with heart and kidney disorders. Bioelectrical impedance vector analysis (BIVA) has the potential to be used as a routine method at the bedside for assessment and management of body fluids.
Impedance (Z vector) is a combination of resistance, R (function of intra- and extracellular fluid volume) and reactance, Xc (function of the dielectric material of tissue cells), with the best signal to noise ratio at 50 kHz. BIVA allows a direct assessment of body fluid volume through patterns of vector distribution on the R-Xc plane without the knowledge of the body weight. Reference tolerance ellipses (50, 75 and 95%) for the individual vector were previously calculated in the healthy population.
We determined the optimal vector distribution in patients undergoing hemodialysis without hypotension or intradialytic symptoms. Most vectors lay within the reference 75% tolerance ellipse of the healthy population indicating full electrical restoration of tissues. We also determined the optimal vector distribution of patients undergoing continuous ambulatory peritoneal dialysis without edema and with a residual urine output. The vector distribution was close to the distribution of both healthy subjects and pre-session distribution of hemodialysis patients. We established the relationship between central venous pressure and BIVA in critically ill patients. Shorter vectors (overhydration) were associated with increasing venous pressure, whereas longer vectors were associated with decreasing venous pressure. The association between BIVA and NT-proBNP has been evaluated in patients with acute cardiac-related dyspnea. In the 'gray zone' of NT-proBNP values between 'ruling out' and 'ruling in' acute heart failure, BIVA detected latent peripheral congestion.
Simple patterns of BIVA allow detection, monitoring, and control of hydration status using vector displacement for the feedback on treatment.
体液容量充足可改善心脏和肾脏疾病患者的短期和长期预后。生物电阻抗矢量分析（BIVA）有潜力作为一种床边常规方法用于体液的评估和管理。
阻抗（Z矢量）是电阻R（细胞内液和细胞外液容量的函数）和电抗Xc（组织细胞介电材料的函数）的组合，在50kHz时信噪比最佳。BIVA可通过R-Xc平面上的矢量分布模式直接评估体液容量，而无需知晓体重。先前已在健康人群中计算出个体矢量的参考耐受椭圆（50%、75%和95%）。
我们确定了无低血压或透析中症状的血液透析患者的最佳矢量分布。大多数矢量位于健康人群参考75%耐受椭圆内，表明组织的电功能完全恢复。我们还确定了无水肿且有残余尿量的持续性非卧床腹膜透析患者的最佳矢量分布。该矢量分布接近健康受试者以及血液透析患者透析前的分布。我们建立了危重症患者中心静脉压与BIVA之间的关系。较短的矢量（液体过多）与静脉压升高相关，而较长的矢量与静脉压降低相关。在急性心脏相关呼吸困难患者中评估了BIVA与NT-proBNP之间的关联。在NT-proBNP值处于排除和诊断急性心力衰竭的“灰色地带”时，BIVA检测到潜在的外周充血。
BIVA的简单模式可通过矢量位移检测、监测和控制水化状态，为治疗提供反馈。
