Codognotto Marta, Piazza Michele, Frigatti Paolo, Piccoli Antonio
Department of Medical and Surgical Sciences, University of Padova, Padova, Italy.
Nutrition. 2008 Jun;24(6):569-74. doi: 10.1016/j.nut.2008.02.009.
Tetrapolar whole-body (hand-foot) bioelectrical impedance (Z-body) is used in body composition analysis assuming homogeneous soft tissue hydration. Limbs and trunk contribute to Z-body by 90% and 10%, respectively. We determined the effect on Z-body of an edema localized in one leg.
Resistance (R) and reactance (Xc) components of Z vector were measured at 50 kHz (BIA-101, RJL Systems, Akern, Italy) in 20 adult male patients without edema, before and 3 d after a femoropopliteal bypass that induced pitting edema in the leg. Z-body was measured from hand to foot on the right and left sides. Z from the leg (Z-leg) was measured from the pair of electrodes on the foot and the other pair on the trochanter. Data were analyzed with the vector bioelectric impedance analysis (Vector BIA) method (Piccoli's RXc graph with 95% confidence ellipses).
Before surgery, the positions of the mean Z-body and Z-leg vectors from either side of the body were not significantly different (overlapping 95% confidence ellipses). After surgery, the mean Z-leg and Z-body vectors from the side without edema did not change position in the RXc plane with respect to the presurgery position. In contrast, the mean Z-leg and Z-body vectors of the body side with edema significantly (P < 0.05) shortened according to the Vector BIA patterns of fluid accumulation.
Z-body in the side of the body without edema is not sensitive to the edema localized in the leg on the opposite side and therefore can be used in the assessment of body composition in patients with edema in one leg.
四极全身（手足）生物电阻抗（Z体）用于身体成分分析，假设软组织水合均匀。四肢和躯干对Z体的贡献分别为90%和10%。我们确定了单腿局部水肿对Z体的影响。
在20名无水肿的成年男性患者中，于股腘动脉搭桥术前及术后3天，采用50 kHz频率（BIA-101，RJL Systems，意大利阿克恩）测量Z向量的电阻（R）和电抗（Xc）分量。分别在身体左右两侧从手到脚测量Z体。从足部电极对和转子上的另一对电极测量腿部的Z（Z腿）。采用向量生物电阻抗分析（Vector BIA）方法（带有95%置信椭圆的皮科利RXc图）分析数据。
手术前，身体两侧平均Z体和Z腿向量的位置无显著差异（95%置信椭圆重叠）。手术后，无水肿一侧的平均Z腿和Z体向量在RXc平面上相对于术前位置未发生变化。相比之下，有水肿一侧身体的平均Z腿和Z体向量根据液体潴留的Vector BIA模式显著缩短（P < 0.05）。
身体无水肿一侧的Z体对另一侧腿部的局部水肿不敏感，因此可用于评估单腿水肿患者的身体成分。
