Leypoldt J K, Cheung A K, Deeter R B
Research Service, Veterans Affairs Medical Center, Salt Lake City, UT 84148, USA.
ASAIO J. 1997 Nov-Dec;43(6):904-9. doi: 10.1097/00002480-199711000-00011.
Methods for evaluating dialyzer clearance of beta 2-microglobulin during clinical hemodialysis have not been well established. The authors show, theoretically, that the postdialysis-to-predialysis concentration ratio, a parameter often used to estimate dialyzer clearance of beta 2-microglobulin, depends on KdT/V (the dialyzer clearance times the treatment time divided by the distribution volume for beta 2-microglobulin) and the ultrafiltration rate, assuming that a single compartment kinetic model is valid. They also show that adjustment of the postdialysis concentration of beta 2-microglobulin for changes in its volume of distribution does not entirely correct for fluid removal when the adjusted postdialysis-to-predialysis concentration ratio is significantly below one. These considerations suggest that estimates of dialyzer clearance of beta 2-microglobulin using single compartment models are more reliable than those using only the postdialysis-to-predialysis concentration ratio. To illustrate these constructs, the authors compared experimental estimates of beta 2-microglobulin clearance during clinical hemodialysis using single compartment models with those measured directly from the arteriovenous concentration difference across the dialyzer. First-use low flux and high flux-dialyzers and those reprocessed with Renalin were studied. Single compartment estimates of beta 2-microglobulin clearance for low flux dialyzers were similar to those measured directly across the dialyzer, but single compartment estimates of beta 2-microglobulin clearance for high flux dialyzers exceeded (p < 0.001) those measured directly across the dialyzer, independent of whether fluid removal during hemodialysis was assumed to be removed entirely from the extracellular compartment or proportionally from both intracellular and extracellular compartments. The authors conclude that accurate estimates of beta 2-microglobulin clearance for high flux dialyzers will require kinetic models that are more complex than those assuming a uniform distribution of beta 2-microglobulin in a single, well-mixed compartment.
在临床血液透析过程中，评估透析器对β2-微球蛋白清除率的方法尚未完全确立。作者从理论上表明，透析后与透析前浓度比这一常用于估计透析器对β2-微球蛋白清除率的参数，取决于KdT/V（透析器清除率乘以治疗时间除以β2-微球蛋白的分布容积）和超滤率，前提是单室动力学模型有效。他们还表明，当调整后的透析后与透析前浓度比显著低于1时，针对β2-微球蛋白分布容积变化对透析后浓度进行调整，并不能完全校正液体清除的影响。这些考虑表明，使用单室模型估计透析器对β2-微球蛋白的清除率比仅使用透析后与透析前浓度比更可靠。为了说明这些概念，作者将使用单室模型对临床血液透析期间β2-微球蛋白清除率的实验估计值与直接通过透析器动静脉浓度差测量的值进行了比较。研究了首次使用的低通量和高通量透析器以及用Renalin重新处理过的透析器。低通量透析器的单室β2-微球蛋白清除率估计值与直接通过透析器测量的值相似，但高通量透析器的单室β2-微球蛋白清除率估计值超过了（p<0.001）直接通过透析器测量的值，无论血液透析期间的液体清除被假定为完全从细胞外液清除还是按比例从细胞内液和细胞外液清除。作者得出结论，对于高通量透析器，要准确估计β2-微球蛋白清除率，需要比假设β2-微球蛋白在单一充分混合的室中均匀分布的模型更复杂的动力学模型。
