How large is the variability of relative blood volume during haemodialysis?
How large is the variability of relative blood volume during haemodialysis?
复制标题
血液透析过程中相对血容量的变异性有多大？
DOI：
10.1093/ndt/16.2.431
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
A. Montanaro
中科院分区：
文献类型：
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作者：
C. Basile;R. Giordano;A. Montanaro
先生，我们饶有兴趣地阅读了克雷普尔等人的论文《血液透析过程中相对血容量的变异性》。W1x。他们得出结论，相对血容量(RBV)监测在预防透析相关低血压方面的价值有限，因为个体内和个体间的变异性很大。当我们分析克雷塞尔等人的论文中的表3和表4时，我们感到震惊。W1x，患者4的数据与研究的其他9名患者的数据有很大的不同。我们证实，从统计学的角度来看，患者4必须被认为是异常值‘，通过这种方式，当检查RBV的个体行为变化与时间和超滤量UV)绘制的图2a和2b时，必须被排除在统计分析之外：在这些图表中，有一个患者的RBV百分比在超滤期间持续增加，至少在透析的前60分钟：这真的是一个非常奇怪的行为！我们假设这名患者对应于表3和表4中的患者4。考虑到患者4是异常值‘是解释本研究结果的一个关键点，因为只有少数患者进入研究。因此，如果我们重新分析表3中显示的数据(不包括患者4)，我们可以看到个体内和个体间的变异性都显著降低(表1)：个体内平均变异系数在240分钟时从18%到120分钟时为54%；个体间变异系数在60分钟时从15%到180分钟时为34%)。如表1所示，观察到的最大差异是个体内平均CV。不排除在研究的所有时间点，不仅是作者发现的60分钟和240分钟，在RBV变化和UV之间存在统计上显著的相关性。此外，RBV与心率、血压和下腔静脉测量的相关性的统计学意义也可能改变。由于无法获得原始数据，我们无法计算这些相关性。
Sir, We read with interest the paperVariability of relative blood volume during haemodialysis' by Krepel et al. w1x. They conclude that relative blood volume RBV) monitoring is of limited value in the prevention of dialysis-related hypotension due to the large intra-and inter-individual variability w1x. We were struck, when analysing Tables 3 and 4 of the paper by Krepel et al. w1x, by the data of patient 4, which are considerably different from those of the other nine patients of the study. We were confirmed in our opinion that patient 4 must be considered anoutlier', from the statistical point of view, and by that way excluded from the statistical analysis, when examining the individual behaviours of RBV changes plotted against time and ultrafiltration volume UV) Figures 2a and 2b): in these graphs there is one single patient whose percent RBV increases consistently during ultrafiltration, at least in the first 60 min of dialysis: this is really a very bizarre behaviour! We hypothesize that this patient corresponds to patient 4 of Tables 3 and 4. To consider patient 4 anoutlier'is a crucial point in the interpretation of the results of the present work, due to the small number of patients only 10) enrolled into the study. Thus, if we reanalyse the data shown in Table 3 excluding patient 4, we can see that both intra-and inter-individual variability decrease considerably Table 1): the mean intraindividual coefficient of variance CV) by a percentage ranging from 18 at 240 min) to 54% at 120 min); the interindividual CV by a percentage ranging from 15 at 60 min) to 34% at 180 min). As shown in Table 1, the largest differences are observed in mean intra-individual CV. It is not excluded that a statistically significant correlation between RBV changes and UV may be found at all time points studied, and not only at 60 and 240 min, as found by the authors w1x. Furthermore, the statistical significance of the correlations between RBV and heart rate, blood pressure, and inferior caval vein measurement might change too. We could not calculate these correlations due to unavailability of the raw data.