Journois D, Safran D
Département d'Anesthésie-Réanimation, Hôpital Laënnec, Paris.
Ann Fr Anesth Reanim. 1991;10(4):379-89. doi: 10.1016/s0750-7658(05)80814-7.
Continuous haemofiltration (CHF) mimics physiological glomerular filtration. Blood flows through a haemofilter, which is permeable to water and to all those substances not bound to plasma proteins, of up to about 6,000 d molecular weight. Ten to twenty liters of ultrafiltrate (UF) can be filtered daily. Solute concentration in this UF is very similar to that in plasma water. Because of the large volumes involved, the UF must be replaced continuously with an electrolyte solution. Electrolyte and acid-base disturbances can thus be easily and rapidly corrected. There are different techniques of CHF. Continuous arteriovenous haemofiltration (CAVH) avoids the use of an external blood pump, as the patient's own arterial pressure is used to drive the blood through the filter via a large-bore arterial catheter. On the other hand, continuous venovenous haemofiltration (CVVH) requires the use of a blood pump with a pressure alarm and an air bubble detector. Supplementary diffusive transport [CAVH(D),CVVH(D)] can improve the clearance of low molecular weight toxins, such as urea. In these techniques, there is a continuous flow of dialysate in the UF compartment of the haemofilter. One of the major problems with CHF is the anticoagulation of patients who are at risk of developing haemorrhagic complications. Unfractionated heparin is used most often, but other drugs have been used: low molecular weight heparin, prostacyclin, nafamostat, or sodium citrate. The neutralization of heparin has also been suggested. Because the fluid balance can be easily managed by CHF, patients in acute renal failure can be given standard intravenous feeding. Many small endogenous molecules, such as gastrin, are probably removed by CHF. However, most drugs have a molecular weight less than 6,000 d, and are not totally protein-bound. They are therefore likely to be ultrafiltered, and so, become inefficient. As a result, the drugs used should be adapted to the haemofilter, and vice versa. More than any extracorporeal circulation, CHF increases the incidence of bacterial blood contamination, because of its continuous use. Routine blood cultures should be carried out. Moreover, blood is cooled during its passage in the extracorporeal circuit, leading to hypothermia. There are some devices which prevent this. Renal function can be completely replaced with the production of 12 to 15 l UF a day. CHF must be started early on in the course of the renal failure. When the concentration of blood urea is greater than 40 mmol.l-1 diffuse transport must also be used.(ABSTRACT TRUNCATED AT 400 WORDS)
连续性血液滤过（CHF）模拟生理性肾小球滤过。血液流经一个血液滤过器，该滤过器对水以及所有分子量高达约6000道尔顿且未与血浆蛋白结合的物质具有通透性。每日可滤出10至20升超滤液（UF）。该超滤液中的溶质浓度与血浆水的溶质浓度非常相似。由于涉及的液体量很大，必须用电解质溶液持续替换超滤液。因此，电解质和酸碱紊乱能够轻松且迅速地得到纠正。CHF有不同的技术。连续性动静脉血液滤过（CAVH）避免使用外部血泵，因为利用患者自身的动脉压通过大口径动脉导管驱动血液通过滤器。另一方面，连续性静脉 - 静脉血液滤过（CVVH）需要使用带有压力警报器和气泡探测器的血泵。补充性扩散转运[CAVH(D)、CVVH(D)]可提高低分子量毒素（如尿素）的清除率。在这些技术中，透析液在血液滤过器的超滤液腔室中持续流动。CHF的主要问题之一是有发生出血并发症风险的患者的抗凝问题。最常使用普通肝素，但也使用过其他药物：低分子量肝素、前列环素、那法莫司或柠檬酸钠。也有人建议中和肝素。由于CHF能够轻松管理液体平衡，急性肾衰竭患者可接受标准静脉营养。许多内源性小分子，如胃泌素，可能会被CHF清除。然而，大多数药物分子量小于6000道尔顿，且并非完全与蛋白结合。因此它们很可能被超滤，从而变得无效。结果，所使用的药物应根据血液滤过器进行调整，反之亦然。与任何体外循环相比，CHF因持续使用而增加了细菌血液污染的发生率。应进行常规血培养。此外，血液在体外循环过程中会被冷却，导致体温过低。有一些装置可防止这种情况发生。每天产生12至15升超滤液可完全替代肾功能。CHF必须在肾衰竭病程早期开始。当血尿素浓度大于40 mmol·L⁻¹时，还必须使用扩散转运。（摘要截取自400字）
