it 指代的对吗？

Dialysis involves a process in which uremic blood is placed on one side of a semipermeable membrane and dialysate fluid on the other. The dialysate fluid contains normal levels of serum electrolytes so the higher (i.e., abnormal concentrations) of these substances, as well as uremic toxins, may flow through the membrane into the dialysate fluid, thereby cleansing the uremic patient. Currently , this treatment is usually performed for 3 to 4 hours at least three times a week. The other modality is peritoneal dialysis, whereby the peritoneal membrane serves in a similar fashion as the semipermeable membrane. Here, dialysate fluid is placed into the peritoneal space, where it is removed and exchanged for fresh dialysate, substituting for the external artificial kidney

透析包括将尿毒症患者的血液置于半透膜的一侧，透析液置于另一侧的过程。透析液含正常水平的血清电解质，因此较高(即异常浓度)的这些物质以及尿毒症毒素可能会透过膜流入透析液，从而净化尿毒症患者的血液。目前，这种治疗通常每周至少进行三次，每次3到4个小时。另一种方式是腹膜透析，腹膜的作用类似于半透膜。在这里，透析液置入腹腔，在腹腔里用过的透析液被取出并更换为新鲜的透析液，腹膜透析以代替体外人工肾。