Kidney international. Supplement
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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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Despite the wide number of diseases currently or previously treated with plasma exchange and plasmapheresis, the clinical effectiveness of these treatments has been established by large, controlled clinical trials only in few clinical conditions. The firmly accepted and the possible indications for these techniques in critically ill patients are reviewed and discussed, as well as their complications and possible side effects.
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We describe our experience with continuous renal replacement therapy (CRRT) in critically ill neonates. From June 1995 to June 1997 36 critically ill oliguric or anuric infants and children underwent continuous arterio-venous (N = 17) or veno-venous (N = 15) renal support. In addition, four neonates were treated with continuous ultrafiltration (CUF) during extracorporeal membrane oxygenation (ECMO) because of severe diuretic-resistant hypervolemia. ⋯ CRRT related complications included local bleeding at the catheter entrance site, partial thrombosis of the inferior or superior caval veins and transient ischemia due to femoral artery catheters. Continuous hemofiltration either driven in the arterio-venous or veno-venous mode is a very effective method of renal support for critically ill neonates to control fluid balance and metabolic derangement. Urea clearance can be improved by adding some dialysate fluid in a countercurrent direction to blood flow.
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Temporary vascular access is an essential component to perform any extracorporeal renal replacement therapy (RRT) in the acute renal failure patient. RRT used in the acute setting may be categorized in two groups: intermittent (IRRT) and continuous (CRRT). Therapeutic indications are based on clinical and technical considerations. ⋯ Late and/or delayed dysfunctioning of catheters are indicative of a thrombosis. Performance standards of catheters are less of a limiting factor in continuous low flow RRT modalities than in the intermittent ones. Finally, careful handling of the catheter essential to prevent infectious complications.
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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.