Contributions to nephrology
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In the US and Europe, approximately 90% of heart failure (HF) hospitalizations are due to symptoms and signs of sodium and fluid excess. Congestion is associated with HF progression. According to data from large national registries, approximately 40% of hospitalized HF patients are discharged with unresolved congestion, which may contribute to unacceptably high rehospitalization rates. ⋯ Clinical studies of ultrafiltration have shown that removal of isotonic fluid relieves symptoms of congestion, improves cardiac filling pressures and exercise capacity, and restores diuretic responsiveness in patients with diuretic resistance, concomitantly with favorable effects on pulmonary function, ventilatory efficiency, and neurohormonal activation. Ultrafiltration has been shown to reduce rehospitalizations in a randomized controlled trial of patients with decompensated HF. Future larger controlled clinical trials should evaluate the effect of ultrafiltration on survival.
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Since 1984 reports of renal involvement in AIDS patients have been presented in the literature. Different forms of renal disease were noted in the AIDS population including those related to systemic and local renal infections, tubulointerstitial disease, renal involvement by neoplasm and glomerular disease including collapsing glomerulopathy (CG). HIV-associated nephropathy (HIVAN) has been demonstrated to be more severe in the black population. ⋯ In a rat model of CG developed by our group, the injection of serum from CG patients resulted in proteinuria, glomerular tuft retraction and podocyte damage at the ultrastructural level (visceral epithelial cell foot-process effacement). No ultrastructural or light microscopy abnormalities were seen in rats injected with serum from non-collapsing FSGS or healthy subjects. Based on the experience of our group, circulating factors play a dominant role in the pathogenesis of idiopathic CG.
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In order to prevent a disease, its temporal nature (or at least when it starts) needs to be clearly defined. In acute kidney injury (AKI), this is usually not possible because the current diagnostic criteria are retrospective. Contrast-induced nephropathy (CIN) and cardiac surgery-associated acute kidney injury (CSA-AKI) are both thought of as potentially preventable acute renal lesions because the timing of the insult is known precisely. ⋯ Despite this, progress in prevention has been slow, and to date there are no therapies indicated for preventing either CIN or CSA-AKI. The best we can currently do is to recommend aggressive parenteral hydration, avoid compounds we know are nephrotoxic, and avoid unnecessary hypoxia and hypotension. While there is still clearly a long way to go before either of these acute kidney conditions can be described as preventable, the use of major adverse kidney events - death, dialysis and incident or progressive chronic kidney disease at 90 days - as a composite endpoint in clinical trials of putative prevention agents would represent a significant step forwards.
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Fluid management in critically ill patients is a complex process as aggressive fluid resuscitation is commonly utilized for initial hemodynamic support and fluid administration often contributes to fluid retention, particularly when there is impaired kidney function. Recent evidence suggests that fluid accumulation is associated with adverse outcomes. It is unclear whether fluid retention is simply a marker of the severity of organ failure or a mediator of events. In this article we review the evidence and provide a framework for future studies to refine these concepts further.
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Despite the identification of several of the cellular mechanisms thought to underlie the development of acute kidney injury (AKI), the pathophysiology of AKI is still poorly understood. It is clear, however, that instead of a single mechanism being responsible for its etiology, AKI is associated with an entire orchestra of failing cellular mechanisms. Renal microcirculation is the physiological compartment where these mechanisms come together and exert their integrated deleterious action. ⋯ Under pathological conditions, such as inflammation, shock or sepsis, however, the renal microcirculation becomes compromised, which results in a disruption of the homeostasis of nitric oxide, reactive oxygen species, and oxygen supply and utilization. This imbalance results in these compounds exerting pathogenic effects, such as hypoxemia and oxidative stress, resulting in further deterioration of renal microcirculatory function. Our hypothesis is that this sequence of events underlies the development of AKI and that integrated therapeutic modalities targeting these pathogenic mechanisms will be effective therapeutic strategies in the clinical environment.