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Query: UMLS:C0022672 (acute tubular necrosis)
 2,175 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although acute renal artery obstruction causes cessation of kidney function, the viability of the nephron is often maintained by collateral circulation. When renal artery blood flow is restored, filtration is resumed and the resulting acute tubular necrosis is gradually resolved as renal tubular cells regenerate. We have observed several different mechanisms of acute renal artery obstruction resulting in anuric renal failure: temporary suprarenal placement of an aortic clamp during absominal aneurysmectomy, resulting in bilateral renal artery occlusion; embolus, presumably of cardiac origin, to a solitary kidney; and thrombosis of the distal aorta extending to a level proximal to the renal arteries. There is no correlation between the duration of renal artery occlusion and the viability of kidney parenchyma. Viability of the kidney can only be determined by visual inspection at operation and response to revascularization. When vascular obstruction is a possible cause of acute anuric renal failure, immediate angiography is indicated. If a correctable vascular lesion is identified, operative intervention is mandatory.
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PMID:Revascularization of the ischemic kidney. 62 86

Acute renal failure (ARF) is characterized by an acute decrease in glomerular filtration rate (GFR). ARF complicates 4% to 23% of intensive care unit admissions, and is associated with a mortality of approximately 50% among critically ill patients. In the intensive care setting the term ARF is usually applied to acute tubular necrosis (ATN), a form of intrinsic ARF caused by ischemia or nephrotoxins. Pathophysiological mechanisms involved in the decline in GFR include tubular obstruction caused by detachment of tubular epithelial cells from the basement membrane and back-leak of glomerular filtrate as a consequence of disruption of the epithelial cell layer. Vascular mechanisms involved in the pathophysiology of ATN are vasoconstriction due to an imbalance between vasoconstrictive and vasodilatory mediators and vascular obstruction caused by cell aggregation. Currently, there is no real time method to monitor renal function comparable to the real time monitoring of blood pressure or arterial oxygen saturation. Urinary output does not reflect glomerular filtration which may be critically reduced despite normal urine volumes and creatinine clearance still provides the clinically most applicable estimate of GFR. Tubular function can be assessed using the fractional excretion of sodium or the ratio of urinary and serum osmolality; both parameters can be obtained from spot samples of urine and serum and no urinary sampling period is necessary. However, both parameters are strongly affected by the administration of loop diuretics and high fluid and sodium inputs which are common in the intensive care unit. We determined the day to day variability of creatinine clearance, fractional excretion of sodium and the urinary to serum osmolality ratio in critically ill patients without renal dysfunction (i.e. creatinine clearance in the normal range) and found differences of 16% for creatinine clearance, 79% for fractional excretion of sodium and 22% for urinary to serum osmolality ratio. Treatment of ARF is mainly supportive and there is no clinically accepted therapy that attenuates the course of ATN. Treatment of the underlying disease and renal replacement therapy are the main options for the treatment of patients with ARF. In critically ill patients continuous venovenous hemo(dia)filtration is the first choice because it provides more hemodynamic and metabolic stability than intermittent therapy. Acute life-threatening hyperkalemia is an indication for intermittent hemodialysis because of the higher efficacy of dialysis in the clearance of low molecular weight substances.
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PMID:[Acute kidney failure. Physiopathology--clinical diagnosis--therapy]. 1084 May 48

Imaging techniques, especially ultrasonography and Doppler, can give an effective assistance in the differential diagnosis of acute renal failure (ARF). An resistance Index (RI) value >0.75 is reported as optimal in attempting differential diagnosis between acute tubular necrosis (ANT) and prerenal ARF. In hepatorenal syndrome (HRS) RIs is very increased. In some renal vasculitis, as nodose panarteritis (PN), hemolytic-uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP), parenchymal perfusion is reduced and RI increased. In lupus nephritis the RI values are correlated with creatinine level and normal RI are considered as a good prognostic tool. In acute primitive or secondary glomerulonephritis (GN), RI value is normal, with diffuse parenchymal hypervascularization. In acute crescentic and proliferative GN and tubulo-interstitial disease, color Doppler (CD) and power Doppler (PD) reveal a decreased renal parenchymal perfusion, which correlates with increased RI values. In acute thrombosis of renal artery, US color Doppler (DUS) reveals either an absence of Doppler signal or a tardus-parvus pulse distal to the vascular obstruction. In this situation it is possible to visualize hyperthropic perforating vessels that redirect their flow from the capsular plexus to the renal parenchyma. In acute thrombosis of the renal vein Doppler analysis of parenchymal vessels reveals remarkable RI values, sometimes with reversed diastolic flow. In postrenal ARF an adjunct to the differentiation between obstruction and non obstructive dilatation can be found through RIs. Diagnostic criteria of obstruction as reported by literature are: RI>0.70 in the obstructed kidney and, mostly, a difference in RI between the 2 kidneys >0.06-0.1.
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PMID:The US color Doppler in acute renal failure. 1578 27