Relton S, Greenberg A, Palevsky P M
Department of Medicine, University of Pittsburgh School of Medicine, Pennsylvania.
ASAIO J. 1992 Jul-Sep;38(3):M691-6. doi: 10.1097/00002480-199207000-00127.
To define the flow dependence of diffusive solute clearance (Kd) during continuous venovenous hemodiafiltration (CVVHD), urea, creatinine, and phosphate clearance were measured during CVVHD, while ultrafiltration was minimized. Studies were performed using AN69, polyacrylonitrile (PAN), and polyamide (PA) hollow fiber hemofilters. To assess the dialysate flow dependence of Kd, clearances were measured at constant blood flow (QB), while dialysate inflow (QDi) was increased incrementally from 8.3 to 33.3 ml/min. Kd increased linearly for all three solutes using all membranes. To assess its blood flow dependence, Kd was measured at blood flows of 50, 75, 100, and 150 ml/min, while QDi was held constant at 33.3 ml/min. The PA membrane showed no flow dependence; for the other membranes, Kd was flow independent for QB > 100 ml/min. At all values of QB and QDi, clearances for the AN69 and PAN membranes were two to three times that of the PA membrane (p < 0.01). Lactate uptake increased with increasing QDi for all three membranes, but did not result in blood lactate accumulation. It is concluded that: 1) small molecule clearance is dialysate flow limited during CVVHD; 2) increasing QB beyond 100 ml/min is unnecessary for maintaining solute clearance; and 3) the PA membrane is unsuitable for CVVHD because of its low diffusive solute clearance.
为了确定持续静脉-静脉血液透析滤过（CVVHD）过程中扩散溶质清除率（Kd）的流量依赖性，在CVVHD过程中对尿素、肌酐和磷酸盐清除率进行了测量，同时将超滤降至最低。使用AN69、聚丙烯腈（PAN）和聚酰胺（PA）中空纤维血液滤过器进行了研究。为了评估Kd对透析液流量的依赖性，在恒定血流量（QB）下测量清除率，同时将透析液流入量（QDi）从8.3 ml/min逐步增加至33.3 ml/min。使用所有三种膜时，所有三种溶质的Kd均呈线性增加。为了评估其对血流量的依赖性，在血流量为50、75、100和150 ml/min时测量Kd，同时将QDi保持在33.3 ml/min不变。PA膜未显示出流量依赖性；对于其他膜，当QB > 100 ml/min时，Kd与流量无关。在所有QB和QDi值下，AN69和PAN膜的清除率是PA膜的两到三倍（p < 0.01）。所有三种膜的乳酸摄取量均随QDi的增加而增加，但未导致血液乳酸积累。得出以下结论：1）CVVHD过程中小分子清除率受透析液流量限制；2）将QB增加至超过100 ml/min对于维持溶质清除率并无必要；3）PA膜因其低扩散溶质清除率而不适用于CVVHD。
