Journal of nephrology
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Journal of nephrology · Jan 2007
ReviewAcute renal failure in critically ill patients: indications for and choice of extracorporeal treatment.
The prescription of extracorporeal therapy for patients with acute renal failure involves many options: dialysis sessions may be intermittent or continuous, semicontinuous or slow-extended, with controversial indications still to be defined also depending on technical and logistic issues and related to the multidisciplinary cooperation needed in the management of critically ill patients. All efforts to evaluate extracorporeal treatments in these patients must be targeted not only towards supporting renal function, but towards all functional and metabolic derangements that can result from artificial blood purification, in any way achievable.
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A well-functioning vascular access for hemodialysis plays a key role in the quality of life and clinical outcome of dialysis patients. A vascular access for dialysis is considered to be adequate when it provides a blood flow of at least 250 ml/min in the standard dialysis and up to 350-400 ml/min in the high-efficiency dialysis. So far, Cimino-Brescia arterio-venous fistula still remains the gold standard among the available vascular accesses. ⋯ The most important complications of vascular access are stenoses, thromboses, infections. Infections, more frequent in synthetic vascular access than in native fistulas, are responsible for the increase in patients' morbidity and, consequently, in public health costs. An integrated multi-professional approach of vascular access, involving nephrologists, vascular surgeons, interventional radiologists, and trained dialysis nurses should be implemented in order to early detect vascular access complications and failure.
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Journal of nephrology · May 2006
ReviewDo central venous catheters have advantages over arteriovenous fistulas or grafts?
Central venous accesses have become an integral component of vascular access procedures for hemodialysis. Although the DOQI guidelines recommend that less than 10% of chronic hemodialysis patients should be maintained on catheters, in some countries higher prevalences are reported, as in the United States and the United Kingdom (18% and 24%, respectively, according to the DOPPS). The native arteriovenous fistulas are still the best suited accesses for hemodialysis. ⋯ In a matched comparison between Tesio twin catheters and Dialock ports (37 vs. 35, respectively), followed for a 2 year period, no significant differences emerged as regards bacteremia incidence, 0.58/1,000 catheter-days in the Tesio catheter group vs. 0.9/1000 catheter-days in the subcutaneous port group, p=0.12; thrombolytic agents needed, 4.5% vs 4.3% of dialysis sessions; or access failure with removal of the device, 8.1% vs 14.2%, p=0.4. The longer duration of antibiotic therapy in the Tesio group (24.6 vs 14.3 days, p=0.006) was due to the higher incidence of cutaneous infectious episodes (3.8 vs 0.16/1,000 catheter-days). In conclusion, although central venous catheter is the vascular access of last choice, in particular cases it can be a useful alternative, provided that strict protocols for nursing care and proper catheter management are implemented in every center.
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Journal of nephrology · Mar 2006
ReviewMetabolic acidosis: pathophysiology, diagnosis and management.
Derangements in the intermediate metabolism of nutrients can lead to organic acid acidoses, which in turn can have severe clinical consequences that include even the patient's death. Lactic acidosis and ketoacidosis represent the most relevant clinical forms of this type of metabolic acidosis. Assessment and proper management of the organic acid acidoses require the intervention of a skillful clinician that balances the potential benefits and risks of the prescribed measures to the specific needs of the individual patient. To this aim, knowledge of the pathophysiology, diagnosis, and therapy of the various forms of acidoses including alkali administration, represent essential requirements.
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Metabolic alkalosis is a primary pathophysiologic event characterized by the gain of bicarbonate or the loss of nonvolatile acid from extracellular fluid. The kidney preserves normal acid-base balance by two mechanisms: bicarbonate reclamation mainly in the proximal tubule and bicarbonate generation predominantly in the distal nephron. Bicarbonate reclamation is mediated mainly by a Na-H antiporter and to a smaller extent by the H-ATPase. ⋯ The effects of metabolic alkalosis on the body are varied and include effects on the central nervous system, myocardium, skeletal muscle, and the liver. Treatment of this disorder is simple, once the pathophysiology of the cause is delineated. Therapy consists of reversing the contributory factors promoting alkalosis and in severe cases, administration of carbonic anhydrase inhibitors, acid infusion, and low bicarbonate dialysis.