Contributions to nephrology
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Fluid balance management in pediatric critically ill patients is a challenging task, since fluid overload (FO) in the pediatric ICU is considered a trigger of multiple organ dysfunction. In particular, the smallest patients with acute kidney injury are at highest risk to develop severe interstitial edema, capillary leak syndrome and FO. Several studies previously showed a statistical difference in the percentage of FO among children with severe renal dysfunction requiring renal replacement therapy. ⋯ The present review will shortly describe nutrition strategies in critically ill children, it will discuss dosages, benefits and drawbacks of diuretic therapy, and alternative diuretic/nephroprotective drugs currently proposed in the pediatric setting. Finally, specific modalities of pediatric extracorporeal fluid removal will be presented. Fluid management, furthermore, is not only the discipline of removing water: it should also address the way to optimize fluid infusions and, above all, one of the most important fluids infused to all ICU patients with renal dysfunction: parenteral nutrition.
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Continuous hemoperfusion therapies are now widely used in critical care, and could prove to be life-saving for patients unable to receive regular hemoperfusion treatments. Unfortunately, due to the inherent difficulties in assessing the effects of treatment upon critically ill patients, the efficacy of this modality has yet to be proven. Instead of focusing exclusively on a particular form of continuous hemoperfusion or a direct comparison between the different types available, this report provides a general overview of the studies reporting on its efficacy across a wide range of conditions. The authors conclude that continuous hemoperfusion could be beneficial in some cases, but this is highly dependent upon the particular modality used.
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It has been reported that various types of blood purification intended for the removal of humoral mediators, such as cytokines, were performed in patients with severe sepsis/septic shock. While high-volume hemofiltration, hemofiltration using high cut-off membrane filters, and direct hemoperfusion with a polymyxin-B immobilized column are widely used in the treatment of severe sepsis/septic shock, we perform continuous hemodiafiltration using a polymethylmethacrylate membrane hemofilter (PMMA-CHDF), which shows an excellent cytokine-adsorbing capacity, for the treatment of severe sepsis/septic shock. ⋯ Furthermore, PMMA-CHDF could remove anti-inflammatory cytokines such as IL-10 from bloodstream, suggesting that it might improve immunoparalysis as well. These findings suggest that PMMA-CHDF is useful for the treatment of patients with severe sepsis/septic shock as a cytokine modulator.
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Several large observational studies or randomized controlled trials in the field of critical care nephrology have been completed and reported, or recently completed or have recently begun recruitment. These studies provide important information to guide our appreciation of current practice and consider new potentially effective intervention for the prevention or attenuation of acute kidney injury or suggest new avenues for the use of renal replacement therapy (RRT) in the treatment of sepsis. In particular, two studies, the ATN study and the RENAL study (both multicenter randomized controlled trials of > 1,000 patients) provide, for the first time, level I evidence to guide the practice of RRT in critically ill patients and to better define the optimal intensity of such RRT in this setting. Clinicians practicing in the field of critical care nephrology need to be aware of these trials, their details, their findings or design or current recruitment rate and likely time of completion to continue to offer their patients the highest level of evidence-based medical care.
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Endotoxin removal by polymyxin B immobilized cartridge inactivates circulating proapoptotic factors.
Severe sepsis and septic shock continue to be major clinical challenges due to high associated mortality. Lipopolysaccharide (LPS) is a component of the cell membrane of Gram-negative bacteria, and is believed to initiate septic-induced signaling, inflammation and organ damage, including acute renal failure. Polymyxin B (PMX-B) hemoperfusion of septic patients can improve survival and decreasing organ dysfunction by removing circulating LPS. Unfortunately, some clinicians have been slow to adopt this novel therapy due to the lack of understanding of the cellular mechanisms involved in this treatment. Apoptosis, or programmed cell death, is known to contribute to acute renal failure and overall organ dysfunction during sepsis, and can be activated by LPS-initiated signaling pathways. Therefore, the protective renal effects associated with PMX-B hemoperfusion of septic patients may result from alterations in cellular apoptosis. This chapter will review recent data regarding the role of apoptosis prevention in the mechanism leading to the improved outcome and decreased acute renal failure associated with PMX-B hemoperfusion during sepsis. ⋯ The protective effects of extracorporeal therapy with PMX-B on the development of acute renal failure result, in part, through its ability to reduce the systemic proapoptotic activity of septic patients on renal cells.