Zehnder C, Gutzwiller J P, Renggli K
Department of Medicine, Kantonsspital, Aarau, Switzerland.
Clin Nephrol. 1999 Sep;52(3):152-9.
Hemodiafiltration is used to increase the convective transport and thereby the elimination of small and middle molecules, mainly beta2-microglobulin (beta2-M) across the dialysis membranes. There is little information concerning urea, creatinine, beta2-M and principally phosphate kinetics during hemodiafiltration in vivo. In this prospective study, we evaluated the transmembrane solute mass removal (TSR) and clearance (Kd) of urea, creatinine and phosphate as well as serum beta2-M reduction rate (beta2-MRR) and collected beta2-M in dialysate plus ultrafiltrate during high-flux hemodialysis (HD) and post-dilutional hemodiafiltration (HDF).
16 patients were studied using a polysulfone capillary filter (1.6 m2 surface area, 40 microm fiber internal diameter and 200 microm, wall thickness) during 2 one-week periods: first week HD 1.6 m2 and second week HDF 1.6 m2. Treatment time was 4 hours, blood flow rate 300 ml/min with constant dialysate and ultrafiltration rates for HD and HDF periods. TSR, Kd, beta2-MRR and beta2-M collection were assessed during the mid-week treatment. In a second part of the study, we repeated the same protocol using a second high-flux polysulfone capillary filter (2.4 m2 surface area, 30 microm fiber diameter and 150 microm wall thickness).
TSR and Kd of urea and creatinine were not improved by HDF, however, HDF increased TSR and Kd of phosphate. Phosphate clearance rose from 120 (HD 1.6 m2) to 159 (HDF 1.6 m2) (p < 0.005) and from 146 (HD 2.4 m2) to 206 (HDF 2.4 m2) (p < 0.005) ml/min. Beta2-MRR increased from 64.1 +/- 8.6 to 77.7 +/- 8.2% (p < 0.005) and from 75.0 +/- 5.1 to 82.9 +/- 8.5% (p < 0.005) during HDF 1.6 m2 and HDF 2.4 m2, respectively. Collected beta2-M remained unchanged. This discrepancy seems to be due to an enhanced beta2-M adsorption to the polysulfone membrane during HDF.
Our results provide a strong evidence that HDF has no advantage over HD with respect to urea and creatinine removal in vivo. However, HDF did improve the elimination of phosphate and should be considered as an additional treatment option for hyperphosphatemia in dialysis patients. HDF improves significantly the elimination of beta2-M.
血液透析滤过用于增加对流转运，从而消除透析膜上的小分子和中分子物质，主要是β2-微球蛋白（β2-M）。关于体内血液透析滤过期间尿素、肌酐、β2-M以及主要是磷酸盐动力学的信息很少。在这项前瞻性研究中，我们评估了高通量血液透析（HD）和后置稀释血液透析滤过（HDF）期间尿素、肌酐和磷酸盐的跨膜溶质清除量（TSR）和清除率（Kd），以及血清β2-M降低率（β2-MRR）和透析液加超滤液中收集的β2-M。
16例患者在两个为期一周的时间段内使用聚砜毛细管滤器（表面积1.6平方米，纤维内径40微米，壁厚200微米）进行研究：第一周为1.6平方米HD，第二周为1.6平方米HDF。治疗时间为4小时，血液流速300毫升/分钟，HD和HDF期间透析液和超滤率恒定。在周中治疗期间评估TSR、Kd、β2-MRR和β2-M收集情况。在研究的第二部分，我们使用第二个高通量聚砜毛细管滤器（表面积2.4平方米，纤维直径30微米，壁厚150微米）重复相同方案。
HDF未改善尿素和肌酐的TSR和Kd，然而，HDF增加了磷酸盐的TSR和Kd。磷酸盐清除率从120（1.6平方米HD）升至159（1.6平方米HDF）（p<0.005），从146（2.4平方米HD）升至206（2.4平方米HDF）（p<0.005）毫升/分钟。在1.6平方米HDF和2.4平方米HDF期间，β2-MRR分别从64.1±8.6%增至77.7±8.2%（p<0.005）和从75.0±5.1%增至82.9±8.5%（p<0.005）。收集的β2-M保持不变。这种差异似乎是由于HDF期间β2-M对聚砜膜的吸附增强。
我们的结果提供了有力证据，表明在体内清除尿素和肌酐方面，HDF并不优于HD。然而，HDF确实改善了磷酸盐的清除，应被视为透析患者高磷血症的一种额外治疗选择。HDF显著改善了β2-M的清除。
