Error propagation in the estimation of glomerular pressure from macromolecule sieving data.
Error propagation in the estimation of glomerular pressure from macromolecule sieving data.
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DOI：
10.1152/ajprenal.1995.268.4.f736
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发表时间：
1995-04
期刊：
影响因子：
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通讯作者：
A. Edwards;W. Deen
中科院分区：
文献类型：
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作者：
A. Edwards;W. Deen
肾小球跨壁液压差（Δ P）对不同大小的大分子的筛分系数（θ i）的理论影响导致了许多尝试使用筛分曲线来无创估计Δ P，结果不一致。本研究的目的是确定在何种程度上的实验误差和理论模型的缺陷限制了使用这种方法获得可靠的估计值的能力。我们的方法是使用肾小球筛分的计算机模拟生成许多组合成的“实验数据”，并通过在存在各种类型和大小的误差的情况下将模型拟合到这些数据来计算Δ P值。无偏实验误差通过向θ i的个体值添加随机量来模拟，并且通过使用基于一种类型的孔径分布的模型来拟合使用不同类型的模型生成的“数据”来研究系统误差。我们发现，仅在theta i中存在随机误差的情况下，如果标准差sigma i为0.2（根据残差的代数符号计算），则delta P的估计几乎在所有时间都准确到+/- 4 mmHg以内，这表明只要随机误差足够小，压力估计准确的可能性很高。当P > 0.2时，当sigma i <或= theta i的2%、5%或10%时，分别有约90%、80%和70%的病例的Δ P拟合值在真实值的+/- 4 mmHg范围内。然而，对来自许多实验研究的已发表数据的分析表明，小σ i和大P的有利条件极难实现，使得不太可能从任何给定的筛选数据集估计Δ P的准确组平均值。要使其成为一种可靠的估计肾小球压力的方法，还需要在实验和理论上取得重大进展。
The theoretical effects of the glomerular transmural hydraulic pressure difference (delta P) on the sieving coefficients (theta i) of macromolecules of varying size have led to a number of attempts to use sieving curves to estimate delta P noninvasively, with inconsistent results. The objective of this study was to determine the extent to which experimental errors and imperfections in the theoretical models limit the ability to obtain reliable estimates of delta P using this method. Our approach was to generate many sets of synthetic "experimental data" using computer simulations of glomerular sieving and to compute values of delta P by fitting models to those data in the presence of various types and magnitudes of errors. Unbiased experimental errors were simulated by adding random amounts to individual values of theta i, and systematic errors were investigated by using a model based on one type of pore-size distribution to fit "data" generated using a model of a different type. We found that with random errors in theta i only, the estimate of delta P was accurate to within +/- 4 mmHg nearly all of the time, provided that the standard deviation, sigma i, was 0.2, as calculated from the algebraic signs of the residuals, indicated a high likelihood that the pressure estimate was accurate, provided that the random errors were sufficiently small. When P > 0.2, the fitted value of delta P was within +/- 4 mmHg of the true value in about 90%, 80%, and 70% of the cases examined when sigma i was < or = 2%, 5%, or 10% of theta i, respectively. An analysis of published data from a number of experimental studies indicated, however, that the favorable conditions of small sigma i and large P are extremely difficult to achieve, making it unlikely that an accurate group-mean value of delta P will be estimated from any given set of sieving data. Significant experimental and theoretical advances will be needed to make this a reliable method for estimating glomerular pressure.