Lukaski Henry C, Hall Clinton B, Siders William A
U.S. Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, North Dakota, USA.
Nutrition. 2007 Jul-Aug;23(7-8):543-50. doi: 10.1016/j.nut.2007.05.001. Epub 2007 Jun 14.
This study tested the hypothesis that bioelectrical impedance vectors, group and individual, are valid indicators of total body water (TBW) and hydration status in women experiencing fluid gain and loss during and after pregnancy.
We measured TBW, assessed with D(2)O dilution, and resistance (R) and reactance (Xc), determined with 800 microA at 50 kHz and standardized for height (H) and plotted on a bivariate (R-Xc) graph, in 15 women, 21-37 y of age, longitudinally before and during pregnancy and postpartum (PP).
Body weight (61.9 +/- 2.3 to 75.5 +/- 2.3 kg) and TBW (31.4 +/- 1.1 to 38.2 +/- 1.1 L) increased (P < 0.05) from before pregnancy to the third trimester of pregnancy and decreased PP (67.0 +/- 2.3 kg and 32.7 +/- 1.1 L, P < 0.05). R/H and Xc/H decreased during pregnancy (P < 0.05, 361 +/- 10 to 318 +/- 10 and 44 +/- 1 to 36 +/- 1 omega/m, respectively) and increased PP (P < 0.05, 355 +/- 10 and 41 +/- 1 Omega/m). Vector length decreased (P < 0.05, 363 +/- 10 to 320 +/- 10 Omega) during pregnancy and increased PP (P < 0.05, 357 +/- 10 Omega). Changes in vector length and TBW during pregnancy and PP were correlated (r = -0.599, P < 0.001). Women with vectors exceeding a 75% tolerance interval had greater TBW gain (10-12 versus 5-6 L) during pregnancy compared with other women with vectors within this tolerance level.
These findings indicate that impedance vectors provide quantitative evidence of hydration status during pregnancy and that the impedance vector method is useful in monitoring hydration status in pregnancy.
本研究检验了以下假设，即生物电阻抗向量，无论是群体还是个体的，都是孕期及产后经历体液增减的女性全身水（TBW）和水合状态的有效指标。
我们测量了15名年龄在21 - 37岁的女性的TBW（采用重水稀释法评估）、电阻（R）和电抗（Xc）（在50 kHz频率下用800微安测量，并根据身高[H]进行标准化，然后绘制在双变量[R - Xc]图上），在怀孕前、孕期和产后进行纵向测量。
体重（从怀孕前的61.9±2.3千克增加到75.5±2.3千克）和TBW（从31.4±1.1升增加到38.2±1.1升）在怀孕前到孕晚期增加（P < 0.05），产后下降（67.0±2.3千克和32.7±1.1升，P < 0.05）。孕期R/H和Xc/H下降（P < 0.05，分别从361±10降至318±10以及从44±1降至36±1欧姆/米），产后增加（P < 0.05，分别为355±10和41±1欧姆/米）。向量长度在孕期下降（P < 0.05，从363±10降至320±10欧姆），产后增加（P < 0.05，357±10欧姆）。孕期和产后向量长度和TBW的变化具有相关性（r = -0.599，P < 0.001）。与向量在该耐受水平内的其他女性相比，向量超过75%耐受区间的女性在孕期TBW增加更多（10 - 12升对5 - 6升）。
这些发现表明阻抗向量为孕期水合状态提供了定量证据，并且阻抗向量法在监测孕期水合状态方面是有用的。
