Shulman T, Heidenheim A P, Kianfar C, Shulman S M, Lindsay R M
Michigan State University/Kalamazoo Center for Medical Studies, Kalamazoo, USA.
ASAIO J. 2001 Nov-Dec;47(6):615-8. doi: 10.1097/00002480-200111000-00009.
The understanding of fluid changes during hemodialysis (HD is essential for reducing complications as well as efficacy of the procedure. Bioimpedance spectroscopy provides a non invasive method of measuring total body water (TBW), the distribution of intra (ICF) and extracellular (ECF) fluids, and their changes during HD. Segmental bioimpedance may be used to measure the same fluid shifts but from different body segments; the technique has previously been shown to com pare well with whole body measures. It is possible that fluid shifts occur differently in different body compartments during HD. Based on previous hemodynamic studies we postulated that during HD ultrafiltration (UF) the body attempts to preserve its central blood volume (cardiopulmonary circula tion plus great vessels), and thus fluid shifts would be greater from the periphery than from central compartments. To test this hypothesis, segmental bioimpedance (Xitron Technolo gies, San Diego, CA) was performed on 11 subjects undergoing HD where ECF and ICF values were obtained from the legs, arms and trunk before and after a period of UF. Blood volume change (ABV%) was also followed using an on-line optical hematocrit (Hct) sensor (Crit-Line monitor, In-Line Diagnostics, UT) where deltaBV% = deltaBV% = (1 - Hct1/Hct0) x 100 (Hct0 = baseline Hct; Hct1 = postultrafiltration Hct) The UF of 2.0 L +/- 0.79 L (M +/- SD) over 75 minutes was associated with a deltaBV% of -9.43% +/- 3.6% (M +/- SD), a significant (Student's paired t-test) reduction in total body (TB) ECF (p < 0.02), a weak correlation in reduction in TBW (p = 0.09) but not in TB ICF. The ECF reductions from the trunk, legs, and arms were all significant (minimum p < 0.02); no ICF changes from these compartments were significant. The amount of ECF reduction was greater from the legs (0.7 L +/- 0.6 L) than the arms (0.12 L +/- 0.08 L) and trunk (0.2 L +/- 0.2 L) (all M +/- SD). Multiple regression analysis showed that TB ECF changes correlated strongly with leg (r = 0.94, p < 0.001) and arm (r = 0.72, p = 0.002) ECF changes but not with trunk changes. deltaBV% correlated weakly with leg (r = 0.45, p = 0.08) and arm (r = 0.42, p = 0.10) ECF changes but not with the trunk. As the deltaBV% represents the net volume change between UF and plasma water refilling, thiss indicates that plasma water is being removed more from the peripheral compartments than from the trunk. These data suggest that plasma refilling during HD to preserve central blood volume is more dynamic from the leg ECF than from elsewhere and may, in turn, explain the frequent occurrence of leg cramps during and after hemodialysis.
了解血液透析（HD）过程中的体液变化对于减少并发症以及提高该治疗程序的疗效至关重要。生物电阻抗光谱法提供了一种非侵入性方法来测量总体液量（TBW）、细胞内液（ICF）和细胞外液（ECF）的分布及其在血液透析过程中的变化。分段生物电阻抗可用于测量相同的体液转移，但来自不同的身体部位；该技术先前已被证明与全身测量结果具有良好的可比性。在血液透析过程中，不同身体腔室中的体液转移可能会有所不同。基于先前的血流动力学研究，我们推测在血液透析超滤（UF）过程中，身体试图维持其中心血容量（心肺循环加大血管），因此外周的体液转移会比中心腔室更大。为了验证这一假设，对11名接受血液透析的受试者进行了分段生物电阻抗测量（Xitron Technologies，加利福尼亚州圣地亚哥），在超滤一段时间前后从腿部、手臂和躯干获取ECF和ICF值。还使用在线光学血细胞比容（Hct）传感器（Crit-Line监测仪，In-Line Diagnostics，犹他州）跟踪血容量变化（ABV%），其中deltaBV% = deltaBV% = (1 - Hct1/Hct0) x 100（Hct0 = 基线Hct；Hct1 = 超滤后Hct）。在75分钟内超滤2.0 L +/- 0.79 L（平均值 +/- 标准差）与deltaBV%为 -9.43% +/- 3.6%（平均值 +/- 标准差）相关，全身（TB）ECF显著降低（Student配对t检验）（p < 0.02），TBW降低存在弱相关性（p = 0.09），但TB ICF无相关性。躯干、腿部和手臂的ECF降低均显著（最小p < 0.02）；这些腔室的ICF无显著变化。腿部的ECF减少量（0.7 L +/- 0.6 L）大于手臂（0.12 L +/- 0.08 L）和躯干（0.2 L +/- 0.2 L）（均为平均值 +/- 标准差）。多元回归分析表明，TB ECF变化与腿部（r = 0.94，p < 0.001）和手臂（r = 0.72，p = 0.002）的ECF变化密切相关，但与躯干变化无关。deltaBV%与腿部（r = 0.45，p = 0.08）和手臂（r = 0.42，p = 0.10） 的ECF变化弱相关，但与躯干无关。由于deltaBV%代表超滤和血浆水再充盈之间的净体积变化，这表明从外周腔室去除的血浆水比从躯干更多。这些数据表明，血液透析过程中为维持中心血容量的血浆再充盈在腿部ECF中比在其他部位更具动态性，这反过来可能解释了血液透析期间及之后腿部痉挛的频繁发生。
