Laboratoire "Hypoxie et poumon" EA2363, Université Paris 13, 74 rue Marcel Cachin, 93017, Bobigny Cedex, France.
Laboratoire d'excellence, GReX, Paris, France.
Ann Biomed Eng. 2018 Dec;46(12):2189-2195. doi: 10.1007/s10439-018-02114-y. Epub 2018 Aug 22.
The measurement of plasma volume (V) in humans and animals is frequently performed by the Evans blue dye dilution method. However, after injection of Evans blue into the circulation, no steady state is observed because of delayed mixing and progressive leakage of dye out of vascular space. Various methods of calculation have been proposed, either with a single blood sampling 5-10 min after dye injection (Single point method), or with extrapolation at time zero of a logarithmic decay (Log linear method). We propose a method based on a two-compartment hypothesis taking into account the initial mixing and the leakage phase in the time course of dye concentration. Nineteen Sprague-Dawley rats were studied in various conditions and blood sampling was performed before and 2, 4 and 6 min after injection of 200 μg Evans blue. A mathematical model was designed to describe the two-compartment hypothesis and allowed the calculation of V and K (rate of disappearance of dye from vascular space). A Bland and Altman representation evidenced an overestimation of V with previous methods and the great dispersion of results with the single point method, especially when using the 6 min point. Calculation of K revealed more accurate with the model than the Log linear method, especially when the mixing rate is slow. We suggest using the two-compartment model to measure V with Evans blue technique in rats. This method also allows precise evaluation of the rate of dye leakage, which could be a good marker of vascular permeability to albumin.
在人类和动物中，血浆容量（V）的测量通常通过 Evans 蓝染料稀释法进行。然而，由于染料在循环中的混合延迟和逐渐渗漏出血管空间，注入 Evans 蓝后不会观察到稳定状态。已经提出了各种计算方法，要么在染料注射后 5-10 分钟进行单次采血（单点法），要么在对数衰减的零时间进行外推（对数线性法）。我们提出了一种基于双室假设的方法，该方法考虑了染料浓度随时间变化过程中的初始混合和渗漏阶段。在各种条件下研究了 19 只 Sprague-Dawley 大鼠，并在注射 200μg Evans 蓝之前以及注射后 2、4 和 6 分钟进行了采血。设计了一个数学模型来描述双室假设，并允许计算 V 和 K（染料从血管空间消失的速率）。Bland 和 Altman 表示法表明，以前的方法高估了 V，单点法的结果分布也很分散，尤其是在使用 6 分钟点时。与 Log 线性法相比，该模型对 K 的计算更准确，尤其是在混合速率较慢时。我们建议在大鼠中使用 Evans 蓝技术通过双室模型来测量 V。该方法还可以精确评估染料渗漏率，这可能是白蛋白血管通透性的良好标志物。
