Seminars in dialysis
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Since the original description of the obesity-survival paradox in 1999, which suggested a survival advantage for overweight and obese patients undergoing hemodialysis, a large body of evidence supporting the paradox has accumulated. The reason for the paradox has yet to be defined. Better nutrition may be a partial explanation, or it may be that in uremic milieu, excessive fat and surplus calories might confer some survival advantage. ⋯ If proven to be correct, it might explain why peritoneal dialysis patients who receive excessive calories through dialysis do not exhibit the paradox and, secondly and more importantly, therapy could be directed to enhance a greater caloric intake by renal failure patients to engender a better survival outcome. Finally, other clinical settings, for example, congestive heart failure, have their own obesity-survival paradox. Thus, the paradox appears to be a wider phenomenon and might merely be the external expression of a larger principle yet to be uncovered.
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Seminars in dialysis · May 2007
ReviewFluid mechanics and clinical success of central venous catheters for dialysis--answers to simple but persisting problems.
Over 60% of patients initiating chronic hemodialysis in the United States have a chronic central venous catheter (CVC) as their first blood access device. Although it would be better if these patients started dialysis with fistulas, the CVC is used because it is a reliable and relatively safe method for obtaining blood access over a period of months. Drawing blood from a vein at 300-400 ml/minute is a relatively delicate and somewhat unpredictable process, and there is always a tendency for the vein wall to draw over the arterial tip and obstruct flow. ⋯ Which is really better, splitsheath or over-the-wire placement? 10. Which dialysis access has a lower complication rate--CVC or arteriovenous (AV) graft? There remain important problems with CVC for dialysis. With a few more improvements, chronic CVC for dialysis could become a painless, effective and safe long-term access for the majority of dialysis patients and acceptable as an alternative to AV grafts.
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Seminars in dialysis · Jan 2007
Inflow reduction by distalization of anastomosis treats efficiently high-inflow high-cardiac output vascular access for hemodialysis.
The arteriovenous fistula used for vascular access for hemodialysis may contribute to development of congestive heart failure. Theses patients can present with frequent episodes of congestive hear failure. Traditional management of high-inflow, a high-cardiac-output fistula generally involves either closure or banding. ⋯ Access loss was due to failed fistuloplasty or thrombosis. To our knowledge, this is the first report demonstrating that inflow reduction obtained by distalization of the anastomosis of the access fistula is feasible and safe for managing high-inflow, high-cardiac-output fistulas. Longer and larger studies of the inflow reduction procedure and its benefits are needed.
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Central vein stenosis is commonly associated with placement of central venous catheters and devices. Central vein stenosis can jeopardize the future of arteriovenous fistula and arteriovenous graft in the ipsilateral extremity. Occurrence of central vein stenosis in association with indwelling intravascular devices including short-term, small-diameter catheters such as peripherally inserted central catheters, long-term hemodialysis catheters, as well as pacemaker wires, has been recognized for over two decades. ⋯ In resistant cases with severe symptoms, occlusion of the functioning vascular access will usually provide relief of symptoms. Further study of mechanisms of development of central vein stenosis and search for a targeted therapy is likely to lead to better ways of managing central vein stenosis. Prevention of central vein stenosis is the key to avoid access failure and other complications from central vein stenosis and relies upon avoidance of central vein stenosis placement and timely placement of arteriovenous fistula in prospective dialysis patient.
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Pulmonary artery catheterization has been a routine part of care for critically ill patients over the past 25 years. Primary hemodynamic data regarding cardiac output and pulmonary pressures can be utilized to make diagnoses and guide therapy. Tissue oxygen delivery and utilization allow inferences about the efficiency of the cardiopulmonary system and the impact of disease and medical therapies on tissue metabolism. ⋯ Optimizing renal perfusion and minimizing pulmonary congestion with precise volume titration are common reasons for performing pulmonary artery catheterization in the intensive care unit. Despite being reassuring to clinicians that hemodynamic therapy is optimal, multiple data from well conducted clinical studies have not demonstrated outcome benefits to patients related to pulmonary artery catheterization. Less invasive techniques to obtain data regarding hemodynamic function are now entering the clinical arena and are being actively investigated.