Kidney international. Supplement
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The anemia of renal failure is caused by the lack of sufficient quantities of endogenous erythropoietin. With the availability of recombinant human erythropoietin (rHuEPO), however, it has become apparent that to achieve a given target, hematocrit requires proper management of iron replacement, as well as the administration of rHuEPO. ⋯ Blood loss is less of a problem in patients on peritoneal dialysis, but poor iron intake and increased demand for iron are also seen, the latter in patients receiving rHuEPO. It is essential, therefore, for renal health professionals to understand iron metabolism in dialysis patients in order to properly balance the therapy of renal anemia with rHuEPO and supplemental iron.
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Serotonin is important for effective renal blood flow (RBF) autoregulation in the normal rat and at two or seven days of reperfusion following renal ischemia. It has been suggested that after these reperfusion periods and during renal perfusion pressure (RPP) lowering, the vasodilatory autoregulation mechanism is not damaged but overwhelmed by increased 5-HT2-mediated vasoconstriction, resulting in complete loss of autoregulation. This study analyzes the influence of the 5-HT2-antagonist ketanserin on RBF autoregulation after two hours or one day of renal reperfusion following ischemia and in a model of cyclosporine (20 mg/kg.day for 10 days)-induced nephrotoxicity. ⋯ Despite an increased response to intrarenal serotonin after two hours of reperfusion, autoregulation was not restored by ketanserin. At one day of reperfusion and with ketanserin, autoregulation was present down to 105 mm Hg. Thus, during the early reflow period, other factors (of decreasing importance) most likely add to autoregulation loss.
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The evolution of technology and biomaterials has permitted a parallel development of renal replacement therapies in the acute, critically ill patient. From the original description of continuous arteriovenous hemofiltration (CAVH), new techniques such as continuous venous venous hemofiltration (CVVH), hemodiafiltration (HDF) and high flux dialysis (HFD) have been developed and clinically utilized. ⋯ In this field, recent observations have suggested the use of hemofiltration with high volumes of fluid exchange. The hardware and software of the newer continuous renal replacement therapy (CRRT) systems are certainly the key points in achieving these results and in safely performing such challenging techniques.
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An in vitro system composed of a plasma separation membrane coupled with natural (charcoal) or synthetic (Amberlite, Amberchrome) types of sorbents was evaluated for the simultaneous removal of proinflammatory cytokines (TNF-alpha, IL-1 beta and IL-8) and cytokine antagonists [interleukin (IL)-1 receptor antagonist (IL-1Ra), soluble tumor necrosis factor-alpha (TNF-alpha) receptor I and II (sTNFR I and II)] in whole blood spiked with bacterial lipopolysaccharide (LPS). These studies showed that plasma filtration rather than ultrafiltration significantly increased the clearance of all cytokines, particularly TNF-alpha, and the synthetic (Amberlite-type of resin) but not natural (uncoated charcoal) membrane could extensively absorb almost 100% of plasma filtered IL-Ra, IL-1 beta and IL-8, but only 40% of TNF-alpha. ⋯ In the complex scenario of sepsis, the simultaneous removal of excess proinflammatory and/or immunomodulatory mediators may play a role in reducing the hemodynamic alterations, thus resulting in enhanced patient survival. Whether this occurs in the human setting awaits the results of an ongoing clinical investigation.
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There is growing interest in quantitative physical chemical analysis of acid-base physiology among intensivists. Acid-base dilemmas seen in the intensive care unit are not always well addressed by the traditional approaches. ⋯ This approach emphasizes the application of accepted physical chemical principles and identification of independent and dependent acid-base variables. In aqueous solutions, water dissociation is the major source of free hydrogen ions.