Contributions to nephrology
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Sepsis is the most common cause of acute kidney injury (AKI). There has been a growing body of evidence demonstrating the association between worsening of kidney function during sepsis and the risk of short- and long-term mortality. AKI in sepsis is associated with poor outcome and independently predicts increased mortality. ⋯ The expanding population of patients with sepsis and AKI, and the associated excess mortality provide a strong basis for further research aimed at addressing more rigorously all potentially modifiable factors to reduce this burden to patients and health care systems. Better insights into bidirectional and synergistic pathways linking sepsis and AKI might open the window for new therapeutic approaches that interrupt this vicious circle. Here, we discuss the rationale for and the current understanding of the bidirectional relationship between AKI and sepsis.
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Sepsis-induced acute kidney injury (AKI) is the most common form of AKI observed in critically ill patients. AKI mortality in septic critically ill patients remains high despite our increasing ability to support vital organ systems. This high mortality is partly due to our poor understanding of the pathophysiological mechanisms of sepsis-induced AKI. ⋯ Sepsis-induced renal microvascular alterations (vasoconstriction, capillary leak syndrome with tissue edema, leukocytes and platelet adhesion with endothelial dysfunction and/or microthrombosis) and/or an increase in intra-abdominal pressure could contribute to an increase in RVR. Further studies are needed to explore the time course of renal microvascular alterations during sepsis as well as the initiation and development of AKI. Doppler ultrasonography combined with the calculation of the resistive indices may indicate the extent of the vascular resistance changes and may help predict persistent AKI and determine the optimal systemic hemodynamics required for renal perfusion.
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Endothelial cells play a key role in initiating and propagating the inflammatory response seen in ischemia, infections and sepsis. Situated in a key position between the epithelial cells and white blood cells (WBC), they interact and respond to signals from both cell types. ⋯ This last event is in large part responsible for a chronic reduction in regional perfusion, subsequent increased vulnerability to recurrent acute kidney injury, and acceleration of chronic kidney disease progression to end-stage renal disease. Glomerular endothelial dysfunction may lead to preglomerular shunting of blood flow allowing kidney blood flow to remain close to normal while resulting in a reduction in glomerular filtration rate.
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Acute kidney injury (AKI) is a serious condition that affects many intensive care unit (ICU) patients. The most common causes of AKI in the ICU are severe sepsis and septic shock. The mortality of AKI in septic critically ill patients remains high despite our increasing ability to support vital organs. ⋯ It would seem logical, therefore, to focus on the glomerulus in trying to understand why such loss of GFR occurs. Recent experimental observations suggest that, at least in the initial phases of septic AKI, profound changes occur which involve glomerular hemodynamics and lead to loss of GFR. These observations imply that changes in the vasoconstrictor tone of both the afferent and efferent arterioles are an important component of the pathogenesis of septic AKI.
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Acute kidney injury (AKI) has been shown to be associated with progression to chronic kidney disease (CKD). Multiple studies have shown that subsets of AKI survivors are at high risk for progression to advanced stage CKD and death. Risk factors associated with AKI survivors progressing to CKD have been identified and include advanced age, diabetes mellitus, decreased baseline glomerular filtration rate, severity of AKI and a low concentration of serum albumin. ⋯ The maintenance phase of AKI is longer in duration in comparison to the initiation phase, and thus the logistics are more amenable to study. However, the mainstay of treatment for the maintenance phase of AKI (renal replacement therapy) has been tested extensively and increasing the dose of renal replacement therapy has not been shown to improve outcome. Therefore, the recovery phase of AKI may represent the best opportunity to intervene in the negative outcomes of AKI.