Pedrini Luciano A, Feliciani Annalisa, Zerbi Simona, Cozzi Giorgio, Ruggiero Pio
Bolognini Hospital, Seriate, Bergamo, Italy.
Nephrol Dial Transplant. 2009 Sep;24(9):2816-24. doi: 10.1093/ndt/gfp207. Epub 2009 May 6.
Mid-dilution haemodiafiltration (MD-HDF), reported as a highly efficient convective-mixed technique, has demonstrated serious drawbacks in relation to the high pressure originating inside the blood compartment of the filter during clinical application. This randomized crossover design study was planned to optimize the efficiency of the MD-HDF technique while reducing its inherent risks.
Fifteen patients on RRT were submitted in random sequence to standard and reverse MD-HDF under similar operating conditions. Efficiency in solute removal was evaluated by measuring urea (U), phosphate (P) and beta2-microglobulin (beta2-m), mean dialysate clearances (K(DQ)) and eKt/V. Blood and dialysate compartment pressures were monitored on-line during the sessions, and instantaneous hydraulic and membrane permeability indexes were calculated.
During standard MD-HDF sessions, unlike with reverse MD-HDF, excessive blood inlet and transmembrane pressure prevented the planned infusion from being maintained. Resistance index and membrane permeability to water and middle molecules substantially improved with reverse MD-HDF. This resulted in higher beta2-m removal (221.3 +/- 81.3 versus 185.1 +/- 65.5 mg/session, P = 0.007). Phosphate removal was comparable, while U removal was greater with standard MD-HDF (K(DQ) 272 +/- 35 versus 252 +/- 29 ml/min, P = 0.002; eKt/V 1.63 +/- 0.23 versus 1.49 +/- 0.17, P = 0.005).
This study demonstrated the ability of MD-HDF to remove significant amounts of medium-sized uraemic compounds and phosphate, but safe rheologic and hydraulic conditions were only maintained by carrying out treatments with the dialyser used in reverse configuration. For this purpose, the larger MD-220 dialyser ensured better tolerance together with higher middle molecules clearance, even though small molecule removal was slightly worsened. The results of this study may provide some insight into the complex interactions between pressures and flux within the original structure of MD-dialysers and help optimize the clinical application of the technique and reduce its risks.
中稀释血液透析滤过（MD-HDF）作为一种高效的对流混合技术，在临床应用中已显示出与滤器血液腔室内产生的高压相关的严重缺点。本随机交叉设计研究旨在优化MD-HDF技术的效率，同时降低其固有风险。
15例接受肾脏替代治疗（RRT）的患者在相似的操作条件下按随机顺序接受标准和逆向MD-HDF治疗。通过测量尿素（U）、磷酸盐（P）和β2-微球蛋白（β2-m）、平均透析液清除率（K(DQ)）和eKt/V来评估溶质清除效率。在治疗过程中在线监测血液和透析液腔室压力，并计算瞬时水力和膜通透性指标。
在标准MD-HDF治疗期间，与逆向MD-HDF不同，过高的血液入口压力和跨膜压力妨碍了计划内的补液维持。逆向MD-HDF使阻力指数以及膜对水和中分子的通透性得到显著改善。这导致更高的β2-m清除率（221.3±81.3对185.1±65.5mg/次，P=0.007）。磷酸盐清除率相当，而标准MD-HDF的尿素清除率更高（K(DQ)272±35对252±29ml/min，P=0.002；eKt/V1.63±0.23对1.49±0.17，P=0.005）。
本研究证明了MD-HDF能够清除大量的中分子尿毒症化合物和磷酸盐，但只有通过使用逆向配置的透析器进行治疗才能维持安全的流变学和水力条件。为此，更大的MD-220透析器确保了更好的耐受性以及更高的中分子清除率，尽管小分子清除率略有下降。本研究结果可能为深入了解MD-透析器原始结构内压力与通量之间的复杂相互作用提供一些见解，并有助于优化该技术的临床应用并降低其风险。
