Radiocontrast-Induced Acute Renal Failure

The intravascular administration of iodinated radiocontrast media can lead to acute renal dysfunction. Even small changes in renal function have been associated with increased morbidity and mortality, making the prevention of radiocontrast nephropathy of paramount importance. This review summarizes the principal risk factors for radiocontrast nephropathy and evidence-based preventive strategies that should be used to limit its occurrence. Risk factors for radiocontrast nephropathy include preexistent kidney disease, diabetes mellitus, dose of radiocontrast used, advanced congestive heart failure, and intravascular volume depletion. Proven preventive measures include volume expansion with intravenous saline or sodium bicarbonate and the use of low-osmolar or iso-osmolar radiocontrast media. Studies evaluating N-acetylcysteine have been conflicting, with meta-analyses suggesting a small beneficial effect. Studies of other pharmacologic agents have not demonstrated clinical benefit.

Renal Klotho expression in patients with acute kidney injury is associated with the severity of the injury

BACKGROUND/AIMS

The potential physiologic roles of Klotho in acute kidney injury (AKI) have recently been demonstrated in animal models. However, to date, there have been no human studies investigating the expression of renal Klotho in AKI.

METHODS

We retrospectively collected biopsy specimens and clinical data of AKI patients between January 2001 and December 2012. Klotho expression was determined by immunohistochemical staining, and the clinical-pathological correlation was examined.

RESULTS

Among the 34 patients diagnosed with acute tubular necrosis or acute tubulointerstitial nephritis, 21 patients without chronic histological lesions were included. The mean age was 37.3 ± 18.5 years and the mean peak creatinine level was 8.2 ± 5.5 mg/dL. In total, 10 patients (47.6%) received temporary renal replacement therapy (RRT); however, 17 patients (81%) showed functional recovery with creatinine levels of < 1.3 mg/dL after 1 month. The intensity of Klotho expression was scored as a percentage of Klotho-positive area. The renal Klotho score showed a significant negative correlation with the initial or peak creatinine level. When the patients were divided into three groups according to the Klotho score (low, middle, high), the low group had a significantly higher peak creatinine level and a more frequent requirement for RRT. However, the Klotho score was not a significant predictor of renal recovery.

CONCLUSIONS

The results demonstrated that renal Klotho expression in humans decreased significantly according to the severity of AKI, regardless of the etiology, and that low expression was associated with a poor short-term outcome.

Safety and diagnostic yield of renal biopsy in the intensive care unit

PURPOSE

Renal biopsy (RB) is occasionally performed in critically ill patients. The safety and impact of RB in this setting have not been reported.

METHODS

A 10-year (2000-2009) retrospective multicentre study was conducted in ten French intensive care units (ICU) on patients who underwent RB during their management. Medical files were retrieved for data analysis.

RESULTS

Seventy-seven patients underwent an RB of which 68 (88 %) were on a native kidney and 9 (12 %) on a transplanted kidney. Percutaneous ultrasound-guided RB was used in most cases (87 %). Fifty-seven per cent of the patients were on mechanical ventilation at the time of RB. RB-related complications occurred in 17 (22 %) patients, two were graded as severe (requirement for kidney embolization, eventually successful). In 35 (51 %) non-transplanted patients, RB established a specific diagnosis other than acute tubular necrosis (ATN), which was diagnosed in only 18 % of patients. In the remaining patients, only non-specific lesions were observed. Therapeutic modifications followed RB in 14 (21 %) non-transplanted patients. Presence of signs of systemic disease involving the renal tract, occurrence of renal failure before hospital admission, and absence of any factor usually associated with ATN significantly predicted the presence of a specific diagnosis at RB other than ATN.

CONCLUSIONS

In this cohort, the contribution of RB to diagnosis and treatment was undeniable, but at the expense of frequent adverse events although most of them were not considered severe.

Tenofovir-induced kidney disease: an acquired renal tubular mitochondriopathy

Tenofovir, used in combination with other antiretroviral agents, is an effective therapy for HIV infection. Although large clinical studies and post-marketing data support a benign renal profile for tenofovir, numerous cases of kidney injury raise concern for nephrotoxic potential. Early human studies and experimental evidence suggested that tenofovir itself was not associated with mitochondrial toxicity within the kidney. However, recent animal data demonstrate that tenofovir causes mitochondrial DNA depletion and mitochondrial toxicity. Herlitz et al. confirm the nephrotoxicity of tenofovir in humans. They describe its clinical consequences, histopathologic findings, and its mitochondrial toxicity in HIV+ patients.

Acute renal failure in the medical ICU still predictive of high mortality

BACKGROUND

We aimed to determine the outcome and certain predictors of outcome for acute renal failure (ARF) in the medical intensive care unit (ICU) at Tygerberg Hospital.

METHOD

We conducted a retrospective, single-centre cohort study over 12 months comprising all patients admitted to the medical ICU with all causes of renal failure or who developed renal failure following admission to the ICU.

RESULTS

Of 198 medical patients admitted to the ICU, ARF occurred in 46 (23.2%). The leading cause of ARF was acute tubular necrosis. The ICU mortality for ARF patients was 47.8%, compared with 17.5% in ICU patients without ARF. Acute haemodialysis was performed in only 17.3% of the 46 ARF patients. Using Cox proportional hazard regression, we found that mean duration of stay (p<0.001), acute physiology and chronic health evaluation II (Apache II) score (p<0.001), mechanical ventilation (p<0.01), dialysis (p<0.04) and multi-organ failure (p<0.05) affected survival time.

CONCLUSIONS

We found that ARF is still associated with a high mortality rate and longer duration of stay, higher Apache II score, and need for mechanical ventilation; dialysis and presence of multi-organ failure were indicators of a higher mortality rate.

Acute tubular necrosis after renal allograft segmental infarction: the nephrotoxicity of necrotic material

OBJECTIVES

Renal allograft dysfunction can be caused by renal vessel thrombosis, acute tubular necrosis, hyperacute or acute rejection, nephrotoxicity induced by cyclosporine or tacrolimus, thrombotic microangiopathy, or urinary tract obstruction.

MATERIALS AND METHODS

We describe a renal transplant recipient in whom oliguria developed during the first week after transplant, although his early renal allograft function was good.

RESULTS

A Doppler ultrasonographic study revealed a lack of perfusion in the lower pole of the allograft. A perfusion defect was noted in the lower pole that was supplied by a polar artery, which had been damaged during engraftment. Light microscopy disclosed tubular cell necrosis without evidence of vascular or humoral rejection.

CONCLUSIONS

We suggest that toxic molecules such as tumor necrosis factor-alpha released from a segmental infarcted area can induce tubular cell damage and necrosis leading to renal allograft dysfunction.

Clinical acute renal failure: diagnosis and management

Acute renal failure (ARF) is frequently encountered in the hospitalized setting. In this article, we discuss the etiology, pathogenesis, preventative therapies, and renal replacement strategies in patients with acute tubular necrosis, the most common form of hospitalized ARF.

Fenoldopam Mesylate in Early Acute Tubular Necrosis: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

BACKGROUND

Acute tubular necrosis (ATN) occurs commonly in critically ill patients and is associated with increased morbidity and mortality. Fenoldopam is a dopamine receptor alpha1-specific agonist that increases renal blood flow in patients with kidney failure. We hypothesized that administration of low-dose fenoldopam during early ATN would decrease the need for dialysis therapy and/or incidence of death at 21 days.

METHODS

We conducted a prospective, randomized, double-blind, placebo-controlled, clinical trial in 155 patients with early ATN. Patients were considered eligible for enrollment if serum creatinine level increased to 50% greater than admission levels within 24 hours and mean arterial pressure was greater than 70 mm Hg. Patients were randomly assigned to the administration of placebo or fenoldopam for 72 hours.

RESULTS

Overall, 22 of 80 patients (27.5%) in the fenoldopam group reached the primary end point compared with 29 of 75 patients (38.7%) in the placebo group (P = 0.235). This 11% absolute reduction in the primary end point was not statistically significant (P = 0.23). Similarly, there was no difference in the incidence of dialysis therapy between patients randomly assigned to fenoldopam (13 of 80 patients; 16.25%) versus the placebo group (19 of 75 patients; 25.3%; P = 0.163). Moreover, there was no statistically significant difference in 21-day mortality rates between the 2 groups (fenoldopam, 13.8% versus placebo, 25.3%; P = 0.068). In secondary analyses, fenoldopam tended to reduce the primary end point in patients without diabetes and postoperative cardiothoracic surgery patients with early ATN (fenoldopam patients without diabetes, 14 of 54 patients [25.9%] versus placebo patients without diabetes, 23 of 52 patients [44.2%]; P = 0.048) and postoperative cardiothoracic patients (6 of 34 patients [17.6%] versus 14 of 36 patients [38.8%]; P = 0.049). Conversely, fenoldopam did not improve the primary end point in patients with diabetes or those with acute renal failure from other causes. A larger multicenter trial using separate randomizations for patients with and without diabetes will be needed to determine the efficacy of fenoldopam mesylate in specific subpopulations with ATN.

CONCLUSION

Fenoldopam does not reduce the incidence of death or dialysis therapy in intensive care unit patients with early ATN.

Proliferation of bone marrow-derived cells contributes to regeneration after folic acid-induced acute tubular injury

Studies of tissue from recipients of bone marrow transplantation or organ allograft suggest that bone marrow-derived cells (BMDC) may differentiate into a variety of nonhematologic tissues, including renal tubular epithelium. The aims of this study were to examine whether BMDC contribute to recovery after acute renal injury and to assess the effects of cytokine mobilization on regeneration. Female mice (6 wk old) were lethally irradiated and transplanted with male bone marrow (BM) cells and later assigned into control, folic acid-treatment, and folic acid-treatment with granulocyte-colony stimulating factor (G-CSF), and control with G-CSF. Tritiated thymidine was given 1 h before death. Kidney sections were stained for a tubular epithelial marker, Y chromosome (in situ hybridization), periodic acid-Schiff staining, and subjected to autoradiography. Renal tubular epithelial cells in S-phase were scored as female (indigenous) or male (BM-derived). This is the first report to show that BMDC can respond by engrafting the renal tubules and undergo DNA synthesis after acute renal injury. BMDC contributed to the renal tubular epithelial cell population, although most (90%) renal tubular regeneration came from female indigenous cells. Some evidence was found for cell fusion between indigenous renal tubular cells and BMDC, but this was infrequent and the significance and consequences of cell fusion in the kidney are unresolved. G-CSF treatment nearly doubled the frequency of thymidine-labeled BM-derived tubular cells and might facilitate the recovery of renal tubular epithelium.

Sepsis and the Kidney

Acute renal failure (ARF) secondary to sepsis is a highly prevalent diagnosis in the ICU setting and continues to be associated with a high rate of morbidity and mortality. The pathophysiology of sepsis-induced acute renal failure involves ischemic or toxic injury to the renal tubular epithelia, resulting in necrosis or apoptosis, and clinically is characterized as acute tubular necrosis. The management of sepsis-induced ARF includes both conventional intermittent hemodialysis and continuous renal replacement therapies. Experimental therapies to improve outcomes in sepsis-associated ARF include the provision of plasmapheresis and adsorption therapies, and the recent development and deployment of a renal tubule assist device.

An improvement in the outcome of acute renal failure

BACKGROUND

Acute renal failure (ARF) requiring hemodialysis (HD) treatment is related to high mortality. The aim of this study was to analyze the influence of age, disease severity, and catabolism intensity on ARF outcome in patients requiring HD treatment during a 15-year period (1987-2001).

METHODS

The retrospective, single-center study included 583 patients, 428 male, 155 female, age 49+/-15 years, treated by intermittent HD using cuprophane membranes with surface area of 1.3 m2. Liano's Acute Tubular Necrosis Individual Severity Score (ATNISS) score and Hypercatabolism Depuration Score (HDS) score were calculated to estimate disease severity and catabolism intensity in ARF patients.

RESULTS

Average age of patients significantly increased during the 15-year period for more than one decade (44 to 55 years; p=0.0359), especially during the last five-year period (47+/-14.5 vs. 53+/-14.7, p=0.00015). Disease severity showed significant increase comparing periods 1992-1996 and 1997-2001 (ATNISS 0.385+/-0.197 vs. 0.437+/-0.208; p=0.00137), while catabolism intensity during these periods was similar (HDS 0.569+/-0.145 vs. 0.582+/-0.127; p=0.357). Despite the older and more severely ill population of ARF patients, mortality showed a sustained decrease during the 15-year period. Mortality in the period from 1987 to 1991 (49/83; 59%) was similar with the period 1992-1996 (chi2=0.44, p=0.5081), but significantly higher than in the period 1997-2001 (114/250; 45.6%; chi2=3.98, p = 0.0471).

CONCLUSION

The results showed an improvement in the outcome of patients with ARF requiring HD treatment, despite increasing age, disease severity, and use of bioincompatible membranes.

Microscopic examination of the urine helps to confirm the recovery of acute tubular necrosis after cadaveric renal transplantation: a case report

INTRODUCTION

Delayed graft function due to acute tubular necrosis (ATN) is frequently seen in kidney transplants from non-heart-beating donors. However, only a biopsy can be used to assess the severity of ATN. Therefore, we studied the validity of microscopic findings in tubular epithelial cells (TECs) from urine as a means to monitor ATN.

MATERIALS AND METHODS

The first voided urine in the morning was examined for the appearance and nuclear cytoplasmic (N/C) ratio of the TECs, using a murine staining with URO-3 monoclonal antibody to detect proximal tubular cells (PTCs).

CASE

A 58-year-old man underwent cadaveric kidney transplantation in January, 2003 using tacrolimus, mycophenolate mofetil, and prednisone following basiliximab induction therapy. His graft did not function immediately; needle biopsy was performed on day 17. The pathological findings showed severe ATN without evidence of acute rejection. A large quantity of TECs was seen in his urine between days 7 and 14. After day 28, TECs with a large N/C ratio and that were URO-3 antibody-positive were detected. Urine volume increased gradually and hemodialysis was not necessary after day 36.

CONCLUSION

The presence of URO-3-positive TECs with large N/C ratios suggests the reconstruction of PTCs. Therefore, it may be useful to monitor TEC findings to assess the severity ATN after cadaveric kidney transplantation.

Prevention and nondialytic treatment of acute renal failure

Based on the progress made during the last few years in understanding the pathophysiology of acute renal failure, a plethora of therapeutic drug and nondrug interventions have been developed and tested in animal and human forms of this disease. The first part of this article focuses on the role of volume expansion and vasopressors in the prevention and treatment of acute renal failure in the critically ill. From all prophylactic measures that have been proposed, volume expansion, or at least correction of volume depletion, remains the most efficient and most evidence-based intervention in these patients. Norepinephrine is, out of all the vasopressors, probably the most appropriate to use in cases of hypotension, provided circulating volume is adequate. In hypotensive septic patients, vasopressin has been shown to be useful. Direct renal vasodilating substances, the most popular still being low-dose dopamine, have never been proved to be useful in carefully performed prospective trials. Moreover dopamine especially is associated with a number of side effects and complications. From the agents acting on tubular factors, the diuretic mannitol and loop diuretics are the most prescribed. Only in specific situations such as rhabdomyolysis and kidney transplant surgery has it been shown that mannitol was able to prevent acute renal failure. The loop diuretics are able, after establishing adequate circulating volume, to promote diuresis in some forms of oliguric acute renal failure; however, some recent papers have shown that the administration of loop diuretics may actually be associated with increased mortality and delayed recovery of renal function. The last few years have seen a number of trials with acetylcysteine in the prevention of mainly radiocontrast nephropathy. Although the results are still conflicting, the majority indicates that acetylcysteine, when applied together with adequate volume expansion, may be a useful drug to incorporate in the standard treatment procedures in patients at risk for acute renal failure. Interventions to stimulate the recovery process of the damaged kidney with growth factors, although theoretically sound, have thus far not led to successful results.

Prognostic value of tubular proteinuria and enzymuria in nonoliguric acute tubular necrosis

BACKGROUND

Acute tubular necrosis (ATN) has high mortality, especially in patients who require renal replacement therapy (RRT). We prospectively studied the diagnostic accuracy of the urinary excretion of low-molecular-weight proteins and enzymes as predictors of a need for RRT in ATN.

METHODS

In 73 consecutive patients with initially nonoliguric ATN, we measured urinary excretion of alpha(1)- and beta(2)-microglobulin, cystatin C, retinol-binding protein, alpha-glutathione S-transferase, gamma-glutamyltransferase, lactate dehydrogenase, and N-acetyl-beta-D-glucosaminidase early in the course of ATN.

RESULTS

Twenty-six patients (36%) required RRT a median of 4 (interquartile range, 2-6) days after detection of proteinuria and enzymuria. Patients who required RRT had higher urinary cystatin C and alpha(1)-microglobulin [median (interquartile range), 1.7 (1.2-4.1) and 34.5 (26.6-45.1) g/mol of creatinine] than patients who did not require RRT [0.1 (0.02-0.5) and 8.0 (5.0-17.5) g/mol of creatinine]. Urinary excretion of cystatin C and alpha(1)-microglobulin had the highest diagnostic accuracies in identifying patients requiring RRT as indicated by the largest areas under the ROC curves: 0.92 (95% confidence interval, 0.86-0.96) and 0.86 (0.78-0.92), respectively. Sensitivity and specificity were 92% (95% confidence interval, 83-96%) and 83% (73-90%), respectively, for urinary cystatin C >1 g/mol of creatinine, and 88% (78-93%) and 81% (70-88%) for urinary alpha(1)-microglobulin >20 g/mol of creatinine.

CONCLUSION

In nonoliguric ATN, increased urinary excretion of cystatin C and alpha(1)-microglobulin may predict an unfavorable outcome, as reflected by the requirement for RRT.

Bone marrow stem cells contribute to repair of the ischemically injured renal tubule

The paradigm for recovery of the renal tubule from acute tubular necrosis is that surviving cells from the areas bordering the injury must migrate into the regions of tubular denudation and proliferate to re-establish the normal tubular epithelium. However, therapies aimed at stimulating these events have failed to alter the course of acute renal failure in human trials. In the present study, we demonstrate that Lin-Sca-1+ cells from the adult mouse bone marrow are mobilized into the circulation by transient renal ischemia and home specifically to injured regions of the renal tubule. There they differentiate into renal tubular epithelial cells and appear to constitute the majority of the cells present in the previously necrotic tubules. Loss of stem cells following bone marrow ablation results in a greater rise in blood urea nitrogen after renal ischemia, while stem cell infusion after bone marrow ablation reverses this effect. Thus, therapies aimed at enhancing the mobilization, propagation, and/or delivery of bone marrow stem cells to the kidney hold potential as entirely new approaches for the treatment of acute tubular necrosis.

Gene transfer-induced local heme oxygenase-1 overexpression protects rat kidney transplants from ischemia/reperfusion injury

Heme oxygenase-1 (HO-1) overexpression using gene transfer protects rat livers against ischemia/reperfusion (I/R) injury. This study evaluates the effects of Ad-HO-1 gene transfer in a rat renal isograft model. Donor LEW kidneys were perfused with Ad-HO-1, Ad-beta-gal, or PBS, stored at 4 degrees C for 24 h, and transplanted orthotopically into LEW recipients, followed by contralateral native nephrectomy. Serum creatinine, urine protein/creatinine ratios, severity of histologic changes, HO-1 mRNA/protein expression, and HO enzymatic activity were analyzed. Ad-HO-1 gene transfer conferred a survival advantage when compared with PBS- and Ad-beta-gal-treated controls, with median survival of 100, 7, and 7 d, respectively (P < 0.01). Serum creatinine levels were elevated at day 7 in all groups (range, 2.2 to 5.8 mg/dl) but recovered to 1.0 mg/dl by day 14 (P < 0.01) in Ad-HO-1 group, which was sustained thereafter. Urine protein/creatinine ratio at day 7 was elevated in both PBS and Ad-beta-gal, as compared with the Ad-HO-1 group (12.0 and 9.8 versus 5.0; P < 0.005); histologically, ATN and glomerulosclerosis was more severe in Ad-beta-gal group at all time points. Reverse transcriptase-PCR-based HO-1 gene expression was significantly increased before reperfusion (P < 0.001) and remained increased in the Ad-HO-1-treated group for 3 d after transplantation. Concomitantly, HO enzymatic activity was increased at transplantation and at 3 d posttransplant in the Ad-HO-1 group, compared with Ad-beta-gal controls (P < 0.05); tubular HO-1 expression was discernible early posttransplant in the Ad-HO-1 group alone. These findings are consistent with protective effects of HO-1 overexpression using a gene transfer approach against severe renal I/R injury, with reduced mortality and attenuation of tissue injury.

Diagnosis and treatment of acute tubular necrosis

BACKGROUND

Acute tubular necrosis (ATN) is common in hospitalized patients, particularly in the intensive care unit. Over the past four decades, the mortality rate from ATN has remained at 50% to 80%.

PURPOSE

To review recent studies of diagnosis and treatment strategies for ATN.

DATA SOURCES

MEDLINE search for all clinical studies of therapies for ATN, supplemented by a review of the references of the identified articles.

STUDY SELECTION

Prospective studies and major retrospective studies evaluating therapies for ATN.

DATA EXTRACTION

Data on the study sample, interventions performed, results, side effects, and duration of follow-up.

DATA SYNTHESIS

Early diagnosis of ATN by exclusion of prerenal and postrenal causes of acute renal failure, examination of urinary sediment, and analysis of urine measures (for example, fractional excretion of sodium in the absence of diuretics) can allow the early involvement of nephrologists and improve survival. Enteral rather than parenteral hyperalimentation in severely malnourished patients may improve survival. Sepsis causes 30% to 70% of deaths in patients with ATN; therefore, avoidance of intravenous lines, bladder catheters, and respirators is recommended. Because septic patients are vasodilated, large volumes of administered fluid accumulate in the lung interstitium of these patients. This condition necessitates ventilatory support, which when prolonged leads to acute respiratory distress syndrome, multiorgan failure, and increased mortality. More aggressive dialysis (for example, given daily) with biocompatible membranes may improve survival in some patients with acute renal failure.

CONCLUSIONS

New information about the importance of early diagnosis and supportive care for patients with ATN has emerged. However, randomized trials of these interventions are needed to test their effect on the morbidity and mortality of ATN.

Acute renal failure in hospitalized patients

Distinguishing among the three categories of acute renal failure is important, as the evaluation and management are tailored to the particular cause. Most cases are due to acute tubular necrosis. To minimize the risk, we should give hospital patients adequate hydration, use potentially nephrotoxic drugs with caution, keep the use of radiographic contrast agents to a minimum, and give patients at risk a nonionic instead of ionic contrast agent when undergoing radiographic procedures.

Apoptotic cell death in renal injury: the rationale for intervention

Cell number abnormalities are frequent in renal diseases, and range from the hypercellularity of postinfectious glomerulonephritis to the cell depletion of chronic renal atrophy. Recent research has shown that apoptosis and its regulatory mechanisms contribute to cell number regulation in the kidney. The potential role of apoptosis ranges from induction and progression to repair of renal injury. Death ligands and receptors, such as tumor necrosis factor and Fas ligand, proapoptotic and antiapoptotic Bcl2 family members and caspases have all been shown to participate in apoptosis regulation in the course of renal cell injury. However, the precise role of these proteins is unclear, and the participation of most known apoptosis regulatory proteins has not been studied. We now review the role of apoptosis in renal injury, the potential molecular targets of therapeutic intervention, the therapeutic weapons to modulate the activity of these targets and the few examples of therapeutic intervention on apoptosis, with emphasis on the acute tubular necrosis.

Severity of illness scores and the outcome of acute tubular necrosis

The outcome of patients with acute renal failure (ARF) due to acute tubular necrosis (ATN) was evaluated in this study. Two hundred and twenty-two patients with a mean age of 55.1+/-17.7 years (range 19-97 years; male 153, female 69) who developed ATN in the period from July 1991 through January 1997 were studied. Patients were divided into four groups according to their APACHE II scores at the time of the diagnosis of ATN. Group I included patients with an APACHE II score of 14 or less (n = 70), Group II with a score of 15-18 (n = 52), Group III with a score of 19-23 (n = 58), and group IV with a score of 24 or above (n = 42). The mean APACHE II score for each of the four study groups was 11+/-0.4, 16+/-0.2, 20+/-0.2, and 29+/-0.7, respectively. Patient survival was evaluated by the Kaplan-Meier analysis with censorship at 12 months. Survival rates at 180 days were 67%, 47%, 39%, and zero%, for group I through IV respectively, chi2 = 27.99, p < 0.0001, with a median survival of >365, 120, 31, and 11 days, for groups I through IV, respectively. For patients with oliguria (n = 88) survival at 180 days was 23% vs. 58% for patients without oliguria (n = 134), p < 0.0001, median survival 13 vs. 364 d. Six months survival of those who required dialysis (n = 79) was 25% vs. 58% for those whom dialysis was not needed (n = 143), p = 0.001, median survival 15 vs. 364 d, respectively. In patients with sepsis (n = 58), 6 months survival was 35% vs. 50% for those without sepsis (n = 164), p = 0.013, median survival 14 vs. 169 d. In patients who required mechanical ventilation (n = 72), 6 months survival was 17% vs. 62% for those who did not need respiratory support (n = 150), p = 0.0001, median survival 13 vs. > 365 d, respectively. Finally, 6 months survival in patients with one (kidney only), two, three, and four organ failure was 76, 30, 11, and zero percent, respectively, p = 0.0001, median survival >365, 16, 11, and 12 days, respectively. We conclude that the use of the APACHE II score for the stratification of the severity of illness could be of clinical utility in predicting mortality in patients with ATN. Other predictors of poor prognosis include the need for dialysis, the presence of oliguria, the need for mechanical ventilation, the presence of sepsis, and the number of failed organs.

Incidental recognition of left subclavian vein obstruction on renal scintigraphy

In a renal transplant recipient with persistently poor graft function, the flow phase of a renal scan incidentally revealed multiple venous collaterals with focally increased vascular activity near the left lobe of the liver (quadrate lobe). This was initially assumed to represent superior vena cava (SVC) obstruction. A renal biopsy was contemplated to exclude acute rejection because of a nondiagnostic flow phase (loss of a bolus effect). However, because the possibility of venous obstruction at the level of the subclavian and/or brachiocephalic veins (without involving the SVC) also existed, another renal scan was performed, with injection of radiotracer into the contralateral arm. This showed a patent SVC and reasonably preserved renal perfusion consistent with acute tubular necrosis. Subsequently, left subclavian vein obstruction was identified. The graft function improved with conservative management for acute tubular necrosis. These findings illustrate the danger of considering only SVC obstruction when collateral flow patterns and focal hot spots in the liver are present.

Acute tubular necrosis due to captopril

Angiotensin-converting enzyme (ACE) inhibitors are standard therapy for congestive cardiac failure. ACE inhibitors have been used worldwide and are usually safe and have relatively few side effects. Hypotension can develop with the first dose of captopril and can lead to symptomatic renal hypoperfusion with subsequent acute renal failure (ARF). The case of a 65-year-old patient with congestive heart failure who developed acute renal failure following the first dose of captopril is described. He required hemodialysis for 8 weeks for the improvement of his renal function and urinary output. The renal biopsy confirmed the presence of acute tubular necrosis. The reversibility of captopril-induced ARF is confirmed and the patient made an uneventful recovery. An immunoallergic mechanism is not thought to have been responsible for this adverse effect. It is advised that caution should be exerted in giving ACE inhibitors to elderly patients with congestive heart failure, particularly if they are on diuretics. Routine biochemical monitoring is suggested before and during captopril therapy.

Acute tubular necrosis in patients with diabetes mellitus

We compared the clinical outcomes of patients with (n = 71) and without (n = 185) diabetes mellitus enrolled into the placebo arm of a large, multicenter clinical trial of patients with acute tubular necrosis (ATN). Compared with the nondiabetic patients, diabetic patients were older (65.5 +/- 12.9 versus 60.7 +/- 18.0 years, P < 0. 05), had higher usual serum creatinine concentration (1.7 +/- 0.6 versus 1.4 +/- 0.5 mg/dL, P < 0.001), and had a higher prevalence of underlying hypertension, coronary artery disease, and congestive heart failure (all P < 0.007). By day 21 after enrollment, neither mortality nor dialysis-free survival was different between the groups. Length of stay for surviving patients, in both the intensive care unit and the hospital, were significantly shorter for the diabetics. Among acute comorbidities predicting mortality or the need for dialysis, sepsis was more prevalent among the nondiabetic patients (18% versus 35%, diabetics versus nondiabetics, P < 0.05). In conclusion, clinical outcomes for diabetic patients with ATN were no worse than for nondiabetic patients, despite their older age and worse underlying renal function. Patients with diabetes mellitus had more chronic cardiovascular disease but were less acutely ill. We speculate that cardiovascular disease is a risk factor for ATN in patients with diabetes mellitus. These results fail to implicate the increasing prevalence of diabetes mellitus in the persistently poor prognosis of patients with ATN.

Spontaneous renal allograft rupture attributed to acute tubular necrosis

A renal allograft recipient receiving triple immunosuppressive therapy developed spontaneous allograft rupture 5 days after her second cadaveric renal transplantation. Renal biopsy showed interstitial edema with severe acute tubular necrosis (ATN). There was no evidence of acute rejection or renal vein thrombosis. The ruptured renal graft was salvaged by an aggressive fluid resuscitation therapy and surgical hemostasis. The renal function was satisfactory on discharge. We conclude that renal allograft rupture can be the result of interstitial edema solely attributed to ATN in the absence of graft rejection. The ruptured graft kidney is potentially salvageable for those patients whose hemodynamic status can be stabilized by appropriate supportive therapy.

31P-magnetic resonance spectroscopy (31P-MRS) of human allografts after renal transplantation

BACKGROUND

31P-Magnetic resonance spectroscopy (31P-MRS) can be used as a non-invasive tool for measuring the relative intracellular concentrations of several phosphorus metabolites in different organs. Various pathological conditions are characterized by different metabolic patterns. We studied the value of 31P-MRS after renal transplantation with both an uneventful and a clinically complicated course.

METHODS

We determined the relative concentrations of phosphate-containing metabolites in renal allografts of humans with 31P-MRS (1.5 Tesla) in the first few weeks after transplantation; 18 patients with an uneventful clinical course and 10 patients who required dialysis after transplantation were examined. Six patients with a stable allograft function 2-3 months after transplantation served as controls.

RESULTS

In patients with primary allograft function, we found a significant correlation between the phosphomonoester/phosphodiester-ratio (PME/PDE) (r = 0.66, r < 0.01) and the time after transplantation, but no correlation between the nucleoside triphosphate (beta-NTP)-concentration (r = -0.11) and the time course. In the patients with primary or early allograft dysfunction caused by histologically proven rejection (n=5), we found a low beta-NTP compared to patients with an uncomplicated clinical course (0.09+/-0.01 vs 0.15+/-0.03), but no differences in the PME/PDE ratio (0.73+/-0.21 vs 0.80+/-0.21). In contrast, the PME/PDE ratio was lowered in three patients with delayed graft function caused by acute tubular necrosis (0.45+/-0.07 vs 0.80+/-0.21), but the beta-NTP concentration was not reduced (0.15+/-0.003 vs 0.15+/-0.03). The 31P-MR spectrum of two patients with cyclosporin A damage was not altered compared to the controls.

CONCLUSIONS

31P-MRS can be used in patients in the early period after renal transplantation. A significant correlation between the PME/PDE ratio and the time course but no change in the beta-NTP concentration was found in patients with primary allograft function in the first 4 weeks after renal transplantation. Different patterns of 31P-MR spectra were observed depending on the different causes of primary and early transplant dysfunction.

Acute renal failure. Focus on advances in acute tubular necrosis

This article has reviewed the most recent thoughts and findings on the pathophysiology and care of ARF. Clearly, we still have much to learn, but an updated practitioner is necessary in order to meet the challenges of this complex disease, as we search for tomorrow's answers.

Use of diuretics in the acute care setting

The use of diuretics in the acute care setting (intensive care units, operating rooms and emergency departments) is an area of significant clinical and laboratory research. These agents are frequently used to facilitate fluid management and in the hopes of protecting the kidneys from injury. The pros and cons of continuous infusion of loop diuretics, and albumin supplementation are discussed along with the issues related to their use to avoid dialysis or to improve outcome. In addition, the evidences is support of the use diuretics to prevent or treat acute failure in the acute care setting are reviewed and discussed.

Acute renal failure after massive ingestion of gliclazide in a suicide attempt

Gliclazide, a sulfonlyurea class molecule, is used to control glycaemic levels in non-insulin-dependent diabetes mellitus. Acute and chronic toxicity studies, conducted in various animal species, have demonstrated a very low toxicity. We report a patient who developed acute renal failure due to acute tubular necrosis following a massive ingestion of gliclazide in an suicide attempt. The patient ingested 28 grams of gliclazide; the normal dose of gliclazide is 80 mg one or twice a day. At admission the patient was hypoglycaemia and in a few days became oliguric with an increase in the serum creatinine concentration, but with a normal blood urea nitrogen level. He underwent dialysis and ten days after ingestion of gliclazide, his renal function improved rapidly.

Predictors of mortality and the provision of dialysis in patients with acute tubular necrosis. The Auriculin Anaritide Acute Renal Failure Study Group

To explore the natural history of critically ill patients with acute renal failure due to acute tubular necrosis, we evaluated 256 patients enrolled in the placebo arm of a randomized clinical trial. Death and the composite outcome, death or the provision of dialysis, were determined with follow-up to 60 d. The relative risks (RR) and 95% confidence intervals (95% CI) associated with routinely available demographic, clinical, and laboratory variables were estimated using proportional hazards regression. Ninety-three (36%) deaths were documented; an additional 52 (20%) patients who survived received dialysis. Predictors of mortality included male gender (RR, 2.01; 95% CI, 1.21 to 3.36), oliguria (RR, 2.25; 95% CI, 1.43 to 3.55), mechanical ventilation (RR, 1.86; 95% CI, 1.18 to 2.93), acute myocardial infarction (RR, 3.14; 95% CI, 1.85 to 5.31), acute stroke or seizure (RR, 3.08; 95% CI, 1.56 to 6.06), chronic immunosuppression (RR, 2.37; 95% CI, 1.16 to 4.88), hyperbilirubinemia (RR, 1.06; 95% CI, 1.03 to 1.08 per 1 mg/dl increase in total bilirubin) and metabolic acidosis (RR, 0.95; 95% CI, 0.90 to 0.99 per 1 mEq/L increase in serum bicarbonate concentration). Predictors of death or the provision of dialysis were oliguria (RR, 5.95; 95% CI, 3.96 to 8.95), mechanical ventilation (RR, 1.53; 95% CI, 1.07 to 2.21), acute myocardial infarction (RR, 1.95; 95% CI, 1.24 to 3.07), arrhythmia (RR, 1.51; 95% CI, 1.04 to 2.19), and hypoalbuminemia (RR, 0.56; 95% CI, 0.42 to 0.74 per 1 g/dl increase in serum albumin concentration). Neither mortality nor the provision of dialysis was related to patient age. These observations can be used to estimate risk early in the course of acute tubular necrosis. Furthermore, these and related models may be used to adjust for case-mix variation in quality improvement efforts, and to objectively stratify patients in future intervention trials aimed at favorably altering the course of hospital-acquired acute renal failure.

The bioartificial renal tubule assist device to enhance CRRT in acute renal failure

Current therapy for acute tubular necrosis (ATN) continues to have an exceedingly high mortality rate, exceeding 50% even with dialytic or hemofiltrative support. Current renal replacement therapy in ATN only substitutes for filtration function of the kidney but not its cellular metabolic functions. Replacing these metabolic functions may optimize current therapy for this devastating disease process. In this regard, a renal tubule assist device (RAD) has been developed to be placed in an extracorporeal continuous hemoperfusion circuit in series with a hemofilter. The RAD consists of porcine renal proximal tubule cells grown as confluent monolayers of a multifiber bioreactor with a membrane surface area from 0.4 to 1.6 m2. The cells along the inner surface of the hollow fibers are immunoprotected from the patient's blood by the hollow fiber membrane. In preliminary experiments in uremic dogs, this device has been shown to tolerate a uremic environment while providing reabsorptive, metabolic, and endocrinologic activity. Pilot human trials of the RAD are anticipated within the next year to improve current renal replacement therapy in ATN.

Early haemodialysis in acute tubular necrosis

The study was conducted in 35 cases of acute tubular necrosis of varied aetiology. Cases were divided in 2 groups, Group A--17 cases treated conservatively and Group B--18 cases managed by early haemodialysis. Criteria for early haemodialysis were blood urea < 120 mg% and serum creatinine < 7 mg%. Before starting therapy both the groups had comparable biochemical and renal parameters (p > 0.05). Overall mortality was lower in Group B as compared to Group A (22.2% Vs 29.4). Complication events such as uraemic encephalopathy, pulmonary oedema, haematemesis and malena, thrombophlebitis and vomiting were significantly lower in Group B (p < 0.05). Hospital stay was also significantly lower (p < 0.05) in Group B (18 +/- 2.5 days Vs 28 +/- 3 days), this can reduce the cost of treatment also.

A practical approach to acute renal failure

Acute renal failure represents a wide variety of renal diseases, which may be challenging to diagnose and even more challenging to treat. As understanding of these diseases improves, so perhaps will clinicians' ability to treat them.

Anaritide in acute tubular necrosis. Auriculin Anaritide Acute Renal Failure Study Group

BACKGROUND

Atrial natriuretic peptide, a hormone synthesized by the cardiac atria, increases the glomerular filtration rate by dilating afferent arterioles while constricting efferent arterioles. It has been shown to improve glomerular filtration, urinary output, and renal histopathology in laboratory animals with acute renal dysfunction. Anaritide is a 25-amino-acid synthetic form of atrial natriuretic peptide.

METHODS

We conducted a multicenter, randomized, double-blind, placebo-controlled clinical trial of anaritide in 504 critically ill patients with acute tubular necrosis. The patients received a 24-hour intravenous infusion of either anaritide (0.2 microgram per kilogram of body weight per minute) or placebo. The primary end point was dialysis-free survival for 21 days after treatment. Other end points included the need for dialysis, changes in the serum creatinine concentration, and mortality.

RESULTS

The rate of dialysis-free survival was 47 percent in the placebo group and 43 percent in the anaritide group (P = 0.35). In the prospectively defined subgroup of 120 patients with oliguria (urinary output, < 400 ml per day), dialysis-free survival was 8 percent in the placebo group (5 of 60 patients) and 27 percent in the anaritide group (16 of 60 patients, P = 0.008). Anaritide-treated patients with oliguria who no longer had oliguria after treatment benefited the most. Conversely, among the 378 patients without oliguria, dialysis-free survival was 59 percent in the placebo group (116 of 195 patients) and 48 percent in the anaritide group (88 of 183 patients, P = 0.03).

CONCLUSIONS

The administration of anaritide did not improve the overall rate of dialysis-free survival in critically ill patients with acute tubular necrosis. However, anaritide may improve dialysis-free survival in patients with oliguria and may worsen it in patients without oliguria who have acute tubular necrosis.

Biocompatible dialysis membranes and acute renal failure: a study in post-operative acute tubular necrosis in cadaveric renal transplant recipients

Previous experimental and human data suggests a detrimental effect on the course of acute renal failure related to exposure of blood to artificial dialysis membranes of poor biocompatibility. We performed a 2.5-year prospective randomized trial to compare the clinical course of acute renal failure (post-operative ischemic acute tubular necrosis, ATN) in patients receiving a cadaveric renal transplant requiring supportive hemodialysis in the immediate post-transplant setting. Patients were randomized to either a cuprophane or polymethylmethacrylate (PMMA) conventional hollow fiber dialyzer. All patients received a standard immunosuppressive regimen which included induction therapy with either horse anti-thymocyte gamma globulin (ATGAM) or the murine anti-CD3 monoclonal antibody (OKT3). Of 53 patients randomized, 17 were excluded (2 for intervening biopsy-proven rejection prior to recovery from ATN, 10 for primary graft nonfunction and 5 for other reasons), leaving 36 evaluable cases of uncomplicated ATN, 18 in each group. There was no difference by age, race, gender, cause of ESRD, immunosuppressive regimen, cold or warm ischemia time, use of pre-transplant dialysis, percent oliguria or the incidence of intra-dialytic hypotension between the 2 groups. There was no difference in the mean time to recovery from ATN posttransplant (8.9 days in the cuprophane group vs 9.5 days in the PMMA group, p = NS) or in the average number of hemodialysis treatments required (3.6 in both groups, p = NS). There was also no difference in long term allograft outcome in terms of the nadir serum creatinine, the number of episodes of subsequent acute rejection or in the development of chronic rejection. An intent-to-treat analysis of all 53 originally randomized patients similarly yielded no significant differences. A subsequent, non-randomized study using a membrane of intermediate biocompatibility (Hemophan) also showed no difference in recovery time from ATN. Bioincompatible membranes do not seem to have a significant clinical impact on the course of recovery of this form of acute renal failure. The striking benefits of biocompatibility in the course of ARF seen in other human trials may relate more to the non-renal systemic toxic effects of bioincompatibility.