'Artificial' Hemodialysis Versus 'Natural' Hemofiltration

摘要

Because the native kidney is a filter and does not engage in the process of dialysis, long-held beliefs in the superiority of blood filtration for eliminating uremic toxins have rarely been challenged. What could be better than the divine prototype?In the early 1960s, shortly after hemodialysis (HD) was first applied as a life-sustaining therapy for patients with chronic irreversible kidney failure, it became clear that the astonishing life-saving effects of HD could not be extended to restore a normal quality of life. Patients continued to suffer from lethargy, poor appetite, occasional nausea and vomiting, and inability to concentrate and function on a par with coworkers. Mortality rates were, and continue to be, much higher than in the general population. The logical answer to the "why" question was that the therapy was incomplete. However, attempts during the late 1960s and early 1970s to increase the intensity or "dose" of dialysis with higher blood and dialysate flow rates, larger membranes, and longer treatment times failed to bring about the desired improvement in outcome. Although early work with dialysis was hampered by adverse effects of the dialysis itself, the original pioneers (as well as some present-day dialysis clinicians) concluded that inadequate removal of toxic large molecules was responsible at least in part for these disappointing results. Early reports of new highly permeable membranes made from synthetic polyacrylonitrile that could cure uremic neuropathy, a uremic complication previously thought to be reversed only by renal transplantation, spurred efforts to develop membranes and delivery systems aimed at removing larger molecules.