crrt+机制与模式完整.pptVIP

CRRT的缺点 ①需要连续抗凝； ②间断性治疗会降低疗效； ③滤过可能丢失有益物质，如抗炎性介质； ④采用乳酸盐替换液对肝功能衰竭患者不利； ⑤能清除分子量小或蛋白结合率低的药物，故其剂量需要调整，难以建立每种药物的应用指南； ⑥费用较高； ⑦尚无确实证据说明CRRT可以改善预后。 ⑧可以出现血液净化常见的一些并发症，如低血压、过敏、空气栓塞等。 The transport of a molecule through a membrane is governed primarily by its molecular weight. Generally, the more a molecule weighs, the larger it is in size and the more resistant it is to transport. The chart gives an indication of relative molecular weights for some of the common molecules that we are concerned with in CRRT. Molecular weights are measured in units called daltons. urea, electrolytes, creatinine - “small” molecules vitamin B12, inulin - “middle” molecules beta 2, albumin - “large” molecules To illustrate the principle of diffusion, picture a cup of water as seen here on the slide. In the cup on the left, a quantity of salt is poured. The salt gradually diffuses through the water from the high salt concentration area to the low salt concentration area until it is evenly distributed. A uniformly salty solution is created as seen in the cup on the right. To illustrate convection, we go back to the use of the cups. The cup now has a concentrated solution on one side of the semipermeable membrane. As fluid moves (by ultrafiltration), solutes small enough to pass through the pores of the membrane move along with the fluid. Change in blood concentration of a specific solute is dependent on the fluid volume removed. This slide illustrates the process of ultrafiltration. We now have two cups of fluid. Each cup contains two compartments separated by a semipermeable membrane. The cup on the left illustrates how the exertion of a positive pressure on the left compartment will PUSH fluid from that compartment to the one on the right. Similarly, looking at the cup on the right side of the slide, a negative pressure applied to the right compartment will PULL fluid from the compartment on the left into that on the right. How does this work in con