[High-volume hemofiltrations]

Abstract

Almost 10 years ago, standard hemofiltration (HF) was carried out at an ultrafiltration (UF) rate of not more than 2 1/hour and only a predilution variant was usually used. However, after Ronco published the results of his study early in the 20th century the situation changed as this study provided evidence that increasing an UF rate up to 35 ml/kg/hr had a positive effect in patients with acute renal failure (ARF). At the same time, there was a new standard for the determination of high-volume HF (HVHF) and new concepts generalized in this paper have emerged. Moreover, two different procedures of HVHF: (1) a continuous high-volume technique providing a rate of 50-70 ml/kg/hr during 24 hours; (2) an intermittent high-volume technique, the so-called HVHF with short courses of treatment, a very high volume at a rate of 100-120 ml/kg/hr during 4-8 hours. Later on this technique came to be called pulse HVHF. Both methods are designated by the abbreviation HVHF, but their concepts and results are slightly different, as will be discussed below. As for the higher doses of plasma replacement therapy, it is necessary to put the results of two recently published studies into routine clinical practice of continuous vein-venous HF (CVVHF) as soon as possible just in 2008. The performed studies suggest the most important role of adequate dosage of CVVHF and show that the use of a dose of 35 ml/kg/hr in critically ill patients with ARF increased survival by almost 20%. These two studies contain today's most vivid evidence, but one awaits the results of other studies that confirm (or do not confirm) these conclusions. In the world where more importance is attached to evidence-based medicine, two first-level studies will yield Stage A recommendations that may be guided by any intensive care specialist using CVVHF in expectation of the results of on-going investigations. Nevertheless, many difficulties are to be surmounted while introducing new procedures into routine intensive care practice. The most cardinal problems are those associated with requirements for blood flow via vascular access with pre- and postdilution procedures, with the type of employed membranes and substituting liquids, and with a possible need for concomitant dialysis. From the strictly practical standpoint, introduction of these changes into routine intensive care practice may be extremely difficult. This will undoubtedly require that physicians and nurses should make joint effects.