Zhu F, Kuhlmann M K, Sarkar S, Kaitwatcharachai C, Khilnani R, Leonard E F, Greenwood R, Levin N W
Renal Research Institute and Beth Israel Medical Center, New York, NY 10128, USA.
Int J Artif Organs. 2004 Feb;27(2):104-9. doi: 10.1177/039139880402700205.
Current concepts of dry weight (DW) prescription are largely based on clinical symptoms because of the difficulty in assessing extracellular fluid volume (ECV) during dialysis. Intradialytic changes in ECV can be recorded as changes in extracellular resistance [Re] by continuous regional calf multifrequency bioimpedance spectroscopy (BIS). We hypothesized that relative changes in calf Re (Re at time '0' over Re at time 't' [R(e-0)/R(e-t)]) will become very small when ECV is reduced towards normal and individual dry weight is reached.
Intradialytic continuous calf BIS was recorded repeatedly in 15 hemodialysis (HD) patients. The first measurement was performed at the prevailing clinical dry weight (CDW). Next measurements were made after post-HD body weight was gradually decreased by 0.2-0.3 kg per treatment. This procedure was iterated over several subsequent treatments until a treatment was observed where changes in R(e-0)/R(e-t) were < 1%. The weight at the end of this treatment was defined as "achieved dry weight (ADW)". Each R(e-0)/R(e-t) curve was fitted using a Matlab program (curve fitting toolbox) to obtain the exact weight at 20 min after beginning of the flattening of the R(e-0)/R(e-t) slope ('dry' weight estimated from BIS, DW-BIS).
Both mean ADW (80.5 +/- 34.1 kg) and mean DW-BIS (80.6 +/- 34.1) were significantly lower than CDW (81.4 +/- 32.0 kg, p < 0.001), but there was no difference between ADW and DW-BIS. However, the average weight reduction from CDW to ADW (0.80 +/- 0.15 kg) was significantly higher than from CDW to DW-BIS (0.66 +/- 0.14 kg, p < 0.001, paired t-test). When ADW was achieved, pre-dialysis systolic blood pressure (SBP) was lower than at CDW (139.3 +/- 32.5 mmHg, vs. 129.4 +/- 33 mmHg, p < 0.05), post-HD SBP did not differ. The incidence of clinical symptoms of underhydration was similar at CDW (15%) and DW-BIS (15%), but higher at ADW (46%).
Intradialytic continuous calf BIS allows the assessment of changes in extracellular calf resistance as an indicator of changes in extracellular fluid volume. Recording of a continuous R(e-0)/R(e-t) slope during dialysis appears to be a promising new tool for the prediction of dry weight in hemodialysis patients.
由于在透析过程中评估细胞外液容量（ECV）存在困难，目前干体重（DW）处方的概念很大程度上基于临床症状。通过连续区域小腿多频生物电阻抗光谱法（BIS），透析过程中ECV的变化可记录为细胞外电阻[Re]的变化。我们假设，当ECV向正常水平降低并达到个体干体重时，小腿Re的相对变化（时间“0”时的Re与时间“t”时的Re之比[R(e-0)/R(e-t)]）将变得非常小。
对15例血液透析（HD）患者反复进行透析过程中的连续小腿BIS记录。首次测量在当时的临床干体重（CDW）下进行。接下来的测量在每次透析后体重逐渐以每次治疗0.2 - 0.3 kg的幅度下降后进行。此过程在随后的几次治疗中重复，直到观察到一次治疗中R(e-0)/R(e-t)的变化<1%。该治疗结束时的体重定义为“实现的干体重（ADW）”。使用Matlab程序（曲线拟合工具箱）对每条R(e-0)/R(e-t)曲线进行拟合，以获得R(e-0)/R(e-t)斜率变平后20分钟时的精确体重（根据BIS估计的“干”体重，DW-BIS）。
平均ADW（80.5±34.1 kg）和平均DW-BIS（80.6±34.1）均显著低于CDW（81.4±32.0 kg，p<0.001），但ADW与DW-BIS之间无差异。然而，从CDW到ADW的平均体重减轻（0.80±0.15 kg）显著高于从CDW到DW-BIS的体重减轻（0.66±0.14 kg，p<0.001，配对t检验）。当达到ADW时，透析前收缩压（SBP）低于CDW时（139.3±32.5 mmHg对129.4±33 mmHg，p<0.05），透析后SBP无差异。脱水临床症状的发生率在CDW（15%）和DW-BIS（15%）时相似，但在ADW时更高（46%）。
透析过程中的连续小腿BIS可用于评估细胞外小腿电阻的变化，作为细胞外液容量变化的指标。在透析过程中记录连续的R(e-0)/R(e-t)斜率似乎是预测血液透析患者干体重的一种有前景的新工具。
