Contributions to nephrology
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The term pre-renal azotemia (or on occasion 'pre-renal renal failure') is frequently used in textbooks and in the literature to indicate an acute syndrome characterized by the presence of an increase in the blood concentration of nitrogen waste products (urea and creatinine). This syndrome is assumed to be due to loss of glomerular filtration rate but is not considered to be associated with histopathological renal injury. Thus, the term is used to differentiate 'functional' from 'structural' acute kidney injury (AKI) where structural renal injury is taken to indicate the presence of so-called acute tubular necrosis (ATN). ⋯ In such patients, several assumptions associated with the 'pre-renal azotemia paradigm' are violated. In particular, there is no evidence that ATN is the histopathological substrate of septic AKI, there is no evidence that urine tests can discriminate 'functional' from 'structural' AKI, there is no evidence that any proposed differentiation leads or should lead to different treatments, and there is no evidence that relevant experimentation can resolve these uncertainties. Given that septic AKI of critical illness now accounts for close to 50% of cases of severe AKI in developed countries, these observations call into question the validity and usefulness of the 'pre-renal azotemia paradigm' in AKI in general.
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Review Comparative Study
Continuous renal replacement in critical illness.
Acute renal failure in the intensive care unit is usually part of the multiple organ dysfunction syndrome, and the complexity of illness in patients with this complication has risen in recent years. Continuous renal replacement therapy (CRRT) was introduced in the late 1970s and early 1980s to compensate for the inadequacies of conventional intermittent hemodialysis (IHD) in the treatment of these patients. IHD was considered aggressive and unphysiological, often resulting in hemodynamic intolerance and limited efficiency. ⋯ However, these studies are generally underpowered and have certain aspects which may influence the interpretation of their results. In addition, the development of hybrid techniques, such as slow extended daily dialysis, makes this a dynamic area of study where the terms of comparison are constantly changing. This article reviews recent trials comparing CRRT and IHD, and discusses their results and limitations.
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Sepsis and multiple organ failure are complex processes that result from dysregulation of the immune response and its associated hematological, hemodynamic and metabolic disturbances. ⋯ Sepsis is a complex process whose expression and treatment are just now being defined. Treatments that minimize the overall host response still represent the most effective strategies.
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Acute renal failure is a common complication in critically ill patients, affecting some 25% of intensive care unit (ICU) admissions, and is associated with high mortality rates of around 40-50%. Acute renal failure in the ICU frequently occurs as part of multiple organ failure (MOF). ⋯ ICU patients with acute renal failure should be managed using a multidisciplinary team approach led by an intensivist. Good collaboration and communication between intensivists and renal and other specialists is essential to insure the best possible care for ICU patients with renal disease.
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Endotoxin is one of the principal biological substances that cause gram-negative septic shock. Lack of clinical success with antiendotoxin or anticytokine therapy has shifted interest to extracorporeal therapies to reduce circulating levels of the mediators of sepsis. Direct hemoperfusion with polymyxin-B-immobilized fiber (PMX-F) is a promising treatment of gram-negative sepsis in critically ill patients. ⋯ In a systematic review of 28 studies (pooled sample size 1,390 patients), the preliminary results of which are described here, PMX-F therapy appeared to significantly lower endotoxin levels, improve blood pressure, and reduce mortality. However, publication bias and lack of blinding need to be considered. These encouraging results need to be verified with large-scale controlled clinical trials.