Acute renal failure

Long-term follow-up of patients after acute kidney injury in the neonatal period: abnormal ambulatory blood pressure findings

Background

Data on the long-term effects of neonatal acute kidney injury (AKI) are limited.

Methods

We invited 302 children who had neonatal AKI and survived to hospital discharge; out of 95 patients who agreed to participate in the study, 23 cases were excluded due to primary kidney, cardiac, or metabolic diseases. KDIGO definition was used to define AKI. When a newborn had no previous serum creatinine, AKI was defined as serum creatinine above the mean plus two standard deviations (SD) (or above 97.5^th percentile) according to gestational age, weight, and postnatal age. Clinical and laboratory features in the neonatal AKI period were recorded for 72 cases; at long-term evaluation (2–12 years), kidney function tests with glomerular filtration rate (eGFR) by the Schwartz formula, microalbuminuria, office and 24-h ambulatory blood pressure monitoring (ABPM), and kidney ultrasonography were performed.

Results

Forty-two patients (58%) had stage I AKI during the neonatal period. Mean age at long-term evaluation was 6.8 ± 2.9 years (range: 2.3–12.0); mean eGFR was 152.3 ± 26.5 ml/min/1.73 m². Office hypertension (systolic and/or diastolic BP ≥ 95^th percentile), microalbuminuria (> 30 mg/g creatinine), and hyperfiltration (> 187 ml/min/1.73 m²) were present in 13.0%, 12.7%, and 9.7% of patients, respectively. ABPM was performed on 27 patients, 18.5% had hypertension, and 40.7% were non-dippers; 48.1% had abnormal findings. Female sex was associated with microalbuminuria; low birth weight (< 1,500 g) and low gestational age (< 32 weeks) were associated with hypertension by ABPM. Twenty-three patients (33.8%) had at least one sign of microalbuminuria, office hypertension, or hyperfiltration. Among 27 patients who had ABPM, 16 (59.3%) had at least one sign of microalbuminuria, abnormal ABPM (hypertension and/or non-dipping), or hyperfiltration.

Conclusion

Even children who experienced stage 1 and 2 neonatal AKI are at risk for subclinical kidney dysfunction. Non-dipping is seen in four out of 10 children. Long-term follow-up of these patients is necessary.

Purtscher-like retinopathy in a paediatric patient with haemolytic uraemic syndrome: A case report and literature review

An 8-year-old boy presented with fever, vomits, bloody diarrhoea, and blurred vision. The patient was diagnosed with Haemolytic Uraemic Syndrome (HUS) due to the symptoms and a positive Verotoxin stool test. Funduscopic examination showed retinal involvement in both eyes, peri-papillary paleness, retinal haemorrhages, and soft "Purtscher Fleckens" exudates. A favourable outcome was achieved after hospital admission and systemic treatment. Dialysis treatment was not needed due the preserved diuresis. Although Purtscher-like retinopathy is very uncommon, ocular examination is mandatory in patients with pancreatitis, autoimmune diseases, and thrombotic microangiopathies, such as HUS.

Pediatric onco-nephrology: time to spread the word : Part I: early kidney involvement in children with malignancy

Onco-nephrology has been a growing field within the adult nephrology scope of practice. Even though pediatric nephrologists have been increasingly involved in the care of children with different forms of malignancy, there has not been an emphasis on developing special expertise in this area. The fast pace of discovery in this field, including the development of new therapy protocols with their own kidney side effects and the introduction of the CD19-targeted chimeric antigen receptor T cell (CAR-T) therapy, has introduced new challenges for general pediatric nephrologists because of the unique effects of these treatments on the kidney. Moreover, with the improved outcomes in children receiving cancer therapy come an increased number of survivors at risk for chronic kidney disease related to both their cancer diagnosis and therapy. Therefore, it is time for pediatric onco-nephrology to take its spot on the expanding subspecialties map in pediatric nephrology.

Purtscher-like retinopathy in a paediatric patient with haemolytic uraemic syndrome: A case report and literature review

An 8-year-old boy presented with fever, vomits, bloody diarrhea, and blurred vision. The patient was diagnosed with haemolytic uraemic syndrome (HUS) due to the symptoms and a positive verotoxin stool test. Funduscopic examination showed retinal involvement in both eyes, peri-papillary paleness, retinal haemorrhages, and soft Purtscher «fleckens» exudates. A favourable outcome was achieved after hospital admission and systemic treatment. Dialysis treatment was not needed due the preserved diuresis. Although Purtscher-like retinopathy is very uncommon, ocular examination is mandatory in patients with pancreatitis, autoimmune diseases, and thrombotic microangiopathies, such as HUS.

Medication Use as a Contributor to Fluid Overload in the PICU: A Prospective Observational Study

In this prospective observational study, we explored the association of daily fluid intake from medication use with fluid overload in 75 children beginning 24 hours after intubation. The mean percent daily fluid intake from medications was 29% in the overall cohort. Excess intake and inadequate output contributed significantly to fluid overload. In the 28 patients who became ≥10% fluid overloaded, the mean percent daily fluid intake from medications was 34%, but just 23% in the patients who did not. Awareness of volume contribution and maximized concentration of parenteral medications when able may lessen the burden of fluid overload.

Accuracy of cystatin C in prediction of acute kidney injury in children; serum or urine levels: which one works better? A systematic review and meta-analysis

BACKGROUND

There is still an ongoing discussion on the prognostic value of cystatin C in assessment of kidney function. Accordingly, the present study aimed to conduct a meta-analysis to provide evidence for the prognostic value of this biomarker for acute kidney injury (AKI) in children.

METHODS

An extensive search was performed in electronic databases of Medline, Embase, ISI Web of Science, Cochrane library and Scopus until the end of 2015. Standardized mean difference (SMD) with a 95% of confidence interval (95% CI) and the prognostic performance characteristics of cystatin C in prediction of AKI were assessed. Analyses were stratified based on the sample in which the level of cystatin C was measured (serum vs. urine).

RESULTS

A total of 24 articles were included in the meta-analysis [1948 children (1302 non-AKI children and 645 AKI cases)]. Serum (SMD = 0.96; 95% CI: 0.68-1.24; p < 0.0001) and urine (SMD = 0.54; 95% CI:0.34-0.75; p < 0.0001) levels of cystatin C were significantly higher in children with AKI. Overall area under the curve of serum cystatin C and urine cystatin C in prediction of AKI were 0.83 (95% CI: 0.80-0.86) and 0.85 (95% CI: 0.81-0.88), respectively. The best sensitivity (value = 0.85; 95% CI: 0.78-0.90) and specificity (value = 0.61; 95% CI: 0.48-0.73), were observed for the serum concentration of this protein and in the cut-off points between 0.4-1.0 mg/L.

CONCLUSION

The findings of the present study showed that cystatin C has an acceptable prognostic value for prediction of AKI in children. Since the serum level of cystatin C rises within the first 24 h of admission in patients with AKI, this biomarker can be a suitable alternative for traditional diagnostic measures.

The path to chronic kidney disease following acute kidney injury: a neonatal perspective

The risk of acute kidney injury (AKI) in hospitalized critically ill neonatal populations without primary renal disease continues to be high, in both term and premature infants. Observational studies have revealed high rates of chronic kidney disease (CKD) in survivors of neonatal AKI. Proposed mechanisms underlying the progression of CKD following AKI include nephron loss and hyperfiltration, vascular insufficiency and maladaptive repair mechanisms. Other factors, including prematurity and low birth weight, have an independent relationship with the development of CKD, but they may also be positive effect modifiers in the relationship of AKI and CKD. The large degree of heterogeneity in the literature on AKI in the neonatal population, including the use of various AKI definitions and CKD outcomes, has hampered the medical community's ability to properly assess the relationship of AKI and CKD in this vulnerable population. Larger prospective cohort studies with control groups which utilize recently proposed neonatal AKI definitions and standardized CKD definitions are much needed to properly quantify the risk of CKD following an episode of AKI. Until there is further evidence to guide us, we recommend that all neonates with an identified episode of AKI should have an appropriate longitudinal follow-up in order to identify CKD at its earliest stages.

Acute kidney injury in the neonate

Critically ill neonates are at risk for acute kidney injury (AKI). AKI has been associated with increased risk of morbidity and mortality in adult and pediatric patients, and increasing evidence suggests a similar association in the neonatal population. This article describes the current AKI definitions (including their limitations), work on novel biomarkers to define AKI, diagnosis and management strategies, long-term outcomes after AKI, and future directions for much-needed research in this important area.

Acute kidney injury in critically ill children: Risk factors and outcomes

BACKGROUND

Acute kidney injury (AKI) is common in patients in the pediatric intensive care unit (PICU) and is associated with poor outcome. We conducted the present study to determine the incidence, risk factors and outcomes of AKI in the PICU.

MATERIALS AND METHODS

We collected data retrospectively from case records of children admitted to the PICU during one year. We defined and classified AKI according to modified pRIFLE criteria. We used multivariate logistic regression to determine risk factors of AKI and association of AKI with mortality and morbidity.

RESULTS

Of the 252 children included in the study, 103 (40.9%) children developed AKI. Of these 103 patients with AKI, 39 (37.9%) patients reached pRIFLE max of Risk, 37 (35.9%) patients reached Injury, and 27 (26.2%) had Failure. Mean Pediatric Risk of Mortality (PRISM III) score at admission was higher in patients with AKI than in controls (P < 0.001).

Urine and serum neutrophil gelatinase-associated lipocalin cut-off point for the prediction of acute kidney injury

Background:

The aim of the present study was to determine the optimum cut-off point of urine and serum neutrophil gelatinase-associated lipocalin (NGAL) for the predictive diagnosis of acute kidney injury (AKI).

Materials and Methods:

This study was a prospective observational study which was performed at Alzahra hospital and Emam Hussein Hospital, Isfahan, Iran. During a period of 4 months, from February 2012 to May 2012, consecutive patients admitted to pediatric intensive care unit (PICU) aged between 1 month and 15 years with glomerular filtration rate (GFR) more than 90 ml/min were enrolled in the study. In all the patients who were enrolled in the study, blood and urine samples were attained on the first, third, and fifth day of admission. Serum and urine NGAL were assessed and compared between patients who developed AKI and who didn’t.

Results:

Of 25 patients who enrolled in the study, 13 developed AKI. For the serum NGAL, the most accurate cut-off point was the fifth day cut-off point which was 163 375 pg/ml (sensitivity: 61.5%, specificity: 94.6%, AUC: 0.76) and urine NGAL cut-off point was 86 040 pg/ml (sensitivity: 50%, specificity: 92.5%, AUC: 0.73).

Conclusions:

In conclusion, we deduced that serum NGAL level significantly elevates in critically ill patients admitted in PICU who develop AKI. Serum and urine NGAL on the fifth day are the best predictors for the AKI with cut-off points 163 375 and 86 040.

Early detection of acute kidney injury by serum cystatin C in critically ill children

BACKGROUND

We prospectively evaluated whether serum cystatin C (CysC) detected acute kidney injury (AKI) earlier than basal serum creatinine (Cr).

METHODS

In 107 pediatric patients at high risk of developing AKI, serum Cr and serum CysC were measured upon admission. Baseline estimated creatinine clearance (eCCl) was calculated using a CysC-based glomerular filtration rate (GFR) equation from a serum Cr measured at the pediatric intensive care unit (PICU) entrance.

RESULTS

The median age was 10 months (interquartile range, 3-36 months). Serum Cr, serum CysC, and eCCl (mean ± standard deviation [range]) were 0.5 ± 0.18 mg/dl (0.2-1.1 mg/dl), 0.53 ± 0.78 (0.01-3.7 mg/l), and 72.55 ± 28.72 (20.6-176.2) ml/min per 1.73 m(2), respectively. The serum CysC level in patients with AKI was significantly higher than children with normal renal function (p < 0.001). The values for the cut-off point, sensitivity, specificity, and the area under curve (AUC) were determined for CysC as 0.6 mg/l, 73.9 %, 78.9 %, and 0.92 [95 % confidence interval (0.82-1)], respectively, and for Cr the values were 0.4 mg/dl, 68 %, 46.2 %, and 0.39, [95 % confidence interval (0.24-0.54)], respectively. The receiver operating characteristics (ROC) curve analysis revealed that CysC had a significantly higher diagnostic accuracy than eCCl (p < 0.001).

CONCLUSIONS

Our results identify that the sensitivity of serum CysC for detecting AKI is higher than that of serum Cr in a heterogeneous pediatric intensive care unit (PICU) population.

Etiology and outcomes of acute kidney injury in Chinese children: a prospective multicentre investigation

Background

The incidence of AKI appears to have increasing trend. Up to now, prospective, multi-center, large-sample epidemiological study done on pediatric AKI on aspects of epidemiological characteristics, causes and outcomes have not reported. It is necessary to develop prospective, multi-center, large-sample epidemiological study in our country on pediatric AKI. The aim of this study was to determine the clinical features, etiology, and outcomes of acute kidney injury (AKI) in Chinese children.

Method

Paediatric patients (≤18 years old) admitted to 27 hospitals (14 children’s hospitals and 13 general hospitals) affiliated with the Medical University were investigated. AKI was defined using the 2005 Acute Kidney Injury Network criteria.

Results

During the study period, 388,736 paediatric patients were admitted. From this total, AKI was diagnosed in 1,257 patients, 43 of whom died. The incidence and mortality of AKI was 0.32% and 3.4% respectively. The mean (± SD) age of patients was 48.4 ± 50.4 months. Among the 1,257 AKI paediatric patients, 632 were less than one year old. Among the AKI paediatric patients, 615 (48.9%) were in stage 1, 277 (22.0%) in stage 2, and 365 (29.0%) in stage 3. The most common causes of AKI were renal causes (57.52%), whereas postrenal (25.69%) and prerenal (14.96%) causes were the least common. The three most common causes of AKI according to individual etiological disease were urolithiasis (22.35%), of which exposure to melamine-contaminated milk accounted for the highest incidence (63.7%); acute glomerulonephritis (10.10%); and severe dehydration (7.48%). A total of 43 AKI patients (3.4%) died during their hospital stay; 15 (34.9%) of the 43 died as a result of sepsis.

Conclusion

Primary renal diseases are a major risk factor for paediatric AKI in China. In terms of specific etiological disease, urolithiasis (postrenal disease) was the leading cause of paediatric AKI in 2008, when the disease was linked to exposure to melamine-contaminated milk. Sepsis is the leading cause of death in Chinese paediatric AKI patients. Future studies should focus on effective ways of controlling renal disorders and sepsis to improve the clinical management of paediatric AKI in China.

Acute kidney injury: A pediatric experience over 10 years at a tertiary care center

BACKGROUND

The etiology of acute kidney injury (AKI) varies in different countries. In addition, the etiology of AKI in hospitalized children is multifactorial. The importance of diagnosing AKI is not only because of short-term high morbidity and mortality rate, but also for its effect on developing chronic kidney disease.

OBJECTIVES

we studied retrospectively AKIs of children who were hospitalized over 10 years in a University hospital.

MATERIALS AND METHODS

A retrospective analysis of the medical recorded data of 180 children less than 18 years treated for AKI in Alzahra Hospital, Isfahan, Iran, were performed during the period of March 2001 to February 2011. For each patient, demographic and anthropometric data, laboratory data, electrocardiographic findings, ultrasound results, etiology of AKI and short-term outcomes were recorded.

RESULTS

The male to female ratio was 1.57 to 1. Mean age was 5.28 ± 6.3 (SD) years and the median was 1.8 years. The more frequent age group was children less than 2 years. The mortality rate was 22.2% (40 patients). The mortality was not correlated with age (p= 0.74). Renal replacement therapy was recommended for 62 patients (34.4%). Mean of the first and last glomerular filtration rate (GFR) were 18.33± 1.12 ml/min/1.73 m² and 52.53 ± 2.98 ml/min/1.73 m², respectively. The most common urinary sediment finding in approximately 70% of the patients was either renal epithelial cell or renal cell cast. Increased kidney echogenicity was the most common ultrasound finding (48%). Using ANOVA regression analysis, the etiology of disease was the only predictor of mortality (p=0.0001).

CONCLUSIONS

We concluded that the mortality is still high in AKI. Furthermore, the poor outcome (defined as low GFR) are higher among patients with low levels of first GFR and higher RIFLE score.

Study Prevalence of Verotoxigenic E.coli Isolated from Urinary Tract Infections (UTIs) in an Iranian Children Hospital

BACKGROUND AND OBJECTIVES

Urinary tract infections (UTI) caused by enterohemorrhagic Escherichia coli (EHEC) is one of the most important diseases in infants and children. If there would not be any useful diagnosis and treatment it may be resulted in diseases such as acute renal failure, thrombocytopenia and hemolytic anemia. The aim of this study was to determine frequency of verotoxigenic E.coli isolates in urine of children with (UTIs) in Mofid children Hospital.

METHODS

During one year from September 2008 to august 2009, urine specimens were taken from children who suspected to UTI admitted to Mofid Children Hospital. E.coli strains that indicated beta hemolytic on sheep blood agar, negative sorbitol fermentation on SMAC (sorbitol macconky agar) and negative motility on SIM were tested by PCR and serologic (VITEC-RPLA kit) methods for detecting toxin genes and production of toxin, respectively.

RESULTS

Among 12572 urine specimens were taken from children admitted to Mofid hospital, we isolated 378 E.coli from urine samples which only 9 isolates were EHEC. Only five EHEC strains (55%) which produced vtx genes, were detected by serologic and PCR methods.

CONCLUSION

The prevalence of urinary infections caused by EHEC strains is very significant because it causes aggravating pathologic effects. Thus we suggest rapid method for identification of this bacteria and proper treatment to Inhibition of unwanted complications.

Advances in pediatric renal replacement therapy for acute kidney injury

The disease spectrum leading to pediatric renal replacement therapy (RRT) provision has broadened over the last decade. In the 1980s, intrinsic renal disease and burns comprised the most common pediatric acute renal failure etiologies; more recent data demonstrate that pediatric acute kidney injury (AKI) most often results from complications of other systemic diseases resulting from the advancements in congenital heart surgery, neonatal care, and bone marrow and solid organ transplantation. In addition, RRT modality preferences to treat critically ill children have shifted from peritoneal dialysis to continuous renal replacement therapy (CRRT) as a result of improvements in CRRT technologies. In this article, we aim to review the pediatric specific causes for RRT provision, emphasizing the emerging practice patterns with respect to modality and timing of treatment. We will focus on the application of different RRT modalities and related outcome of children with AKI who receive RRT.

Acute renal replacement therapy in children with diarrhea-associated hemolytic uremic syndrome: a single center 16 years of experience

Acute kidney injury (AKI) is becoming more prevalent among hospitalized children, its etiologies are shifting, and new treatment modalities are evolving; however, diarrhea-associated hemolytic uremic syndrome (D+HUS) remains the most common primary disease causing AKI in young children. Little has been published about acute renal replacement therapy (ARRT) and its challenges in this population. We describe our single center's experience managing 134 pediatric patients with D+HUS out of whom 58 (43%) required ARRT over the past 16 years. In our cohort, all but one patient were started on peritoneal dialysis (PD). Most patients, 47 (81%), received acute PD on a pediatric inpatient ward. The most common recorded complications in our cohort were peritoneal fluid leaks 13 (22%), peritonitis 11 (20%), and catheter malfunction 5 (9%). Nine patients (16%) needed surgical revision of their PD catheters. There were no bleeding events related to PD despite a mean platelets count of 40.9 (±23.5) × 10³/mm³ and rare use of platelets infusions. Despite its methodological limitations, this paper adds to the limited body of evidence supporting the use of acute PD as the primary ARRT modality in children with D+HUS.

Determinations of renal cortical and medullary oxygenation using blood oxygen level-dependent magnetic resonance imaging and selective diuretics

OBJECTIVE

This study was undertaken to test the hypothesis that blood O2 level-dependent magnetic resonance imaging (BOLD MRI) can detect changes in cortical proximal tubule (PT) and medullary thick ascending limb of Henle (TAL) oxygenation consequent to successive administration of furosemide and acetazolamide (Az). Assessment of PT and TAL function could be useful to monitor renal disease states in vivo. Therefore, the adjunct use of diuretics that inhibit Na reabsorption selectively in PT and TAL, Az and furosemide, respectively, may help discern tubular function by using BOLD MRI to detect changes in tissue oxygenation.

MATERIAL AND METHODS

BOLD MRI signal R2* (inversely related to oxygenation) and tissue oxygenation with intrarenal O2 probes were measured in pigs that received either furosemide (0.05 mg/kg) or Az (15 mg/kg) alone, Az sequentially after furosemide (n = 6 each, 15-minute intervals), or only saline vehicle (n = 3).

RESULTS

R2* decreased in the cortex of Az-treated and medulla of furosemide-treated kidneys, corresponding to an increase in their tissue O2 assessed with probes. However, BOLD MRI also showed decreased cortical R2* following furosemide that was additive to the Az-induced decrease. Az administration, both alone and after furosemide, also decreased renal blood flow (-26% ± 3.5% and -29.2% ± 3%, respectively, P < 0.01).

CONCLUSION

These results suggest that an increase in medullary and cortical tissue O2 elicited by selective diuretics is detectable by BOLD MRI, but may be complicated by hemodynamic effects of the drugs. Therefore, the BOLD MRI signal may reflect functional changes additional to oxygenation, and needs to be interpreted cautiously.

Acute kidney injury in childhood: should we be worried about progression to CKD?

While emerging evidence indicates that the incidence of both acute kidney injury (AKI) and chronic kidney disease (CKD) in children is rising and that the etiologies are dramatically changing, relatively little is currently known regarding the potential for transition from AKI to CKD. Major barriers to assessing for a potential AKI to CKD link have included lack of a standard pediatric AKI definition, narrow focus only on children with AKI who receive renal replacement therapy, and reliance on serum creatinine as the main biomarker to detect and diagnose AKI and CKD. Recent data have validated a multi-dimensional AKI classification system for children and have suggested chronic kidney sequelae in pediatric populations with AKI or at risk for AKI. In addition, a number of novel AKI biomarkers are being rigorously validated as early indicators of incipient CKD. Our goals for this article are to (1) review the recent changes in pediatric AKI and CKD epidemiology, (2) explore the evidence for a potential AKI to CKD link, and (3) propose new clinical and research paradigms to better elucidate the progression from AKI to CKD.

The use of bumetanide for oliguric acute renal failure in preterm infants

OBJECTIVE

To determine the effects of bumetanide in preterm infants with oliguric acute renal failure (OARF).

STUDY DESIGN

Retrospective data review and multivariate analysis of urine output and serum creatinine, blood urea nitrogen, Na, K, Cl, and Ca levels before, during, and after bumetanide therapy in preterm infants with OARF whose conditions did not respond to furosemide therapy.

RESULTS

A total of 35 infants received bumetanide for OARF after an initial trial of furosemide. Their birth weight, gestational age at birth, and postconceptional age at OARF were 811 ± 326 g, 26 ± 2.75 wks, and 29.2 ± 2.7 wks, respectively. Twenty-nine of the 35 infants (83%) responded to bumetanide. Seventeen of the 35 infants subsequently died in the hospital due to multiorgan dysfunction. For the survivors (n = 18) and 11 of 17 of nonsurvivors, urine output increased from 0.6 ± 0.6 mL/kg/hr to 3.0 ± 2.1 mL/kg/hr during bumetanide therapy (p < .0005). Serum creatinine levels increased from 2.13 ± 0.83 mg/dL to 2.3 ± 0.92 mg/dL (p = .04) during bumetanide treatment, whereas blood urea nitrogen levels decreased after bumetanide therapy from 38 ± 19 mg/dL to 31.67 ± 21.6 mg/dL (p = .049). No significant changes were noted in serum sodium, chloride, or calcium concentration.

CONCLUSIONS

Bumetanide therapy significantly increased urine output within 24-48 hrs, but its use was associated with a transient increase in serum creatinine level. Bumetanide can be used in preterm infants to reverse oliguria when therapy with furosemide fails. Prospective, randomized, controlled trials with long-term follow-up in preterm infants are necessary to establish the usefulness of bumetanide for OARF.

Ocular involvement in paediatric haemolytic uraemic syndrome

PURPOSE

The aim of this study was to estimate the frequency and severity of ocular involvement in paediatric patients with haemolytic uraemic syndrome (HUS).

METHODS

The study was designed as an institutional, retrospective, observational case series. Charts for all 87 paediatric patients with HUS treated at the University Children's Hospital Zurich between 1995 and 2007 were reviewed. Patients with ocular involvement were identified and clinical findings presented.

RESULTS

Three of 69 examined patients with HUS showed ocular involvement. Ophthalmic findings in two children were consistent with bilateral Purtscher retinopathy, showing multiple haemorrhages, exudations and superficial retinal whitening. The third child presented with bilateral isolated central intraretinal haemorrhages as a milder form of ocular involvement. In one of the children with Purtscher retinopathy, laser photocoagulation was required for bilateral rubeosis irides and development of disc neovascularization. Longterm outcomes in the two severely affected children showed decreased visual acuity caused by partial atrophy of the optic nerves. In the milder case visual acuity was not impaired at any time.

CONCLUSIONS

A minority of paediatric patients with HUS developed ocular involvement. Acute ocular findings varied in severity from isolated intraretinal haemorrhages to Purtscher-like retinopathy with retinal ischaemia. Longterm complications included the development of neovascularizations and consecutive optic nerve atrophy. Although ocular involvement in HUS seems to be rare, physicians should be aware of this complication because of its possible vision-endangering consequences.

Overview of pediatric renal replacement therapy in acute kidney injury

The disease spectrum leading to pediatric renal replacement therapy (RRT) provision has broadened over the last decade. In the 1980's, intrinsic renal disease and burns comprised the most common pediatric acute kidney injury (AKI) etiologies. More recent data demonstrate that pediatric AKI most often results from complications of other systemic diseases resulting from the advancements in congenital heart surgery, neonatal care, and bone marrow and solid organ transplantation. In addition, RRT modality preferences to treat critically ill children have shifted from peritoneal dialysis to continuous renal replacement therapy (CRRT) as a result of improvements in CRRT technologies. Currently, multicenter prospective outcome studies for critically ill children with AKI are sorely lacking. The aims of this paper are to review the pediatric specific causes necessitating RRT provision with an emphasis on emerging practice patterns with respect to modality and the timing of treatment, and focus upon the application of the different RRT modalities and assessment of the outcome of children with AKI who receive RRT.

Prognosis for children with acute kidney injury in the intensive care unit

To define factors of prognostic importance for critically ill infants and children with acute kidney injury (AKI), we have studied 110 children, ages from 1 month to 180 months, admitted between March 1, 2002 and September 30, 2004 to the intensive care unit of Joana de Gusmão Children's Hospital. These patients represent 8% of all intensive care unit admissions during the entire study period. The diagnosis at admission was primary renal parenchyma disease (eight patients, 7.2%) and secondary renal disease (102 patients, 92.8%). Thirty-seven patients (33.6%) died, all of whom had secondary renal insufficiency; six patients (5.4%) died as a result of septic shock, and 31 (28.2%) patients died from multiple organ failure (MOF). The variables were analyzed using Fisher's exact test for qualitative variables and Student's t-test for quantitative variables. Stratified analysis was performed to assess the relative importance of variables using the Mantel-Haenszel technique. Among the variables analyzed, the following were found to be significantly related to mortality: anuria, oliguria, arterial hypotension, need for pressor drugs, need for mechanical ventilation, need for dialysis, the association with MOF, and high values of lactic acid.

Management of acute kidney injury in children: a guide for pediatricians

Acute kidney injury (AKI; previously called acute renal failure) is characterized by a usually reversible increase in the blood concentration of creatinine and nitrogenous waste products and by the inability of the kidney to appropriately regulate fluid and electrolyte homeostasis. The incidence of AKI in children appears to be increasing and the etiology of AKI over the past decades has shifted from primary renal disease to multifactorial causes, particularly in hospitalized children. Renal failure can be divided into prerenal failure, intrinsic renal disease including vascular insults, and obstructive uropathies. The history, physical examination, and laboratory studies including a urinalysis and radiographic studies can establish the likely cause(s) of AKI. Once intrinsic renal failure has become established, management of the metabolic complications of AKI requires meticulous attention to fluid balance, electrolyte status, acid-base balance, and nutrition. Many children with AKI will need renal replacement therapy to remove endogenous and exogenous toxins and to maintain fluid, electrolyte, and acid-base balance until renal function improves. Renal replacement therapy may be provided by peritoneal dialysis (PD), intermittent hemodialysis (HD), or hemofiltration with or without a dialysis circuit. Many factors--including the age and size of the child, the cause of renal failure, the degree of metabolic derangements, blood pressure, and nutritional needs--are considered in deciding when to initiate renal replacement therapy and which modality of therapy to use. The prognosis of AKI is highly dependent on the underlying etiology of the AKI. Children who have AKI as a component of multisystem failure have a much higher mortality rate than children with intrinsic renal disease. Recovery from intrinsic renal disease is also highly dependent on the underlying etiology of the AKI. Children who have experienced AKI from any cause are at risk for late development of renal failure long after the initial insult. Such children need life-long monitoring of their renal function, blood pressure, and urinalysis.

Acute kidney injury in children

Acute kidney injury (AKI) (previously called acute renal failure) is characterized by a reversible increase in the blood concentration of creatinine and nitrogenous waste products and by the inability of the kidney to regulate fluid and electrolyte homeostasis appropriately. The incidence of AKI in children appears to be increasing, and the etiology of AKI over the past decades has shifted from primary renal disease to multifactorial causes, particularly in hospitalized children. Genetic factors may predispose some children to AKI. Renal injury can be divided into pre-renal failure, intrinsic renal disease including vascular insults, and obstructive uropathies. The pathophysiology of hypoxia/ischemia-induced AKI is not well understood, but significant progress in elucidating the cellular, biochemical and molecular events has been made over the past several years. The history, physical examination, and laboratory studies, including urinalysis and radiographic studies, can establish the likely cause(s) of AKI. Many interventions such as 'renal-dose dopamine' and diuretic therapy have been shown not to alter the course of AKI. The prognosis of AKI is highly dependent on the underlying etiology of the AKI. Children who have suffered AKI from any cause are at risk for late development of kidney disease several years after the initial insult. Therapeutic interventions in AKI have been largely disappointing, likely due to the complex nature of the pathophysiology of AKI, the fact that the serum creatinine concentration is an insensitive measure of kidney function, and because of co-morbid factors in treated patients. Improved understanding of the pathophysiology of AKI, early biomarkers of AKI, and better classification of AKI are needed for the development of successful therapeutic strategies for the treatment of AKI.

Nephrotoxicity as a cause of acute kidney injury in children

Many different drugs and agents may cause nephrotoxic acute kidney injury (AKI) in children. Predisposing factors such as age, pharmacogenetics, underlying disease, the dosage of the toxin, and concomitant medication determine and influence the severity of nephrotoxic insult. In childhood AKI, incidence, prevalence, and etiology are not well defined. Pediatric retrospective studies have reported incidences of AKI in pediatric intensive care units (PICU) of between 8% and 30%. It is widely recognized that neonates have higher rates of AKI, especially following cardiac surgery, severe asphyxia, or premature birth. The only two prospective studies in children found incidence rates of 4.5% and 2.5% of AKI in children admitted to PICU, respectively. Nephrotoxic drugs account for about 16% of all AKIs most commonly associated with AKI in older children and adolescents. Nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics, amphotericin B, antiviral agents, angiotensin-converting enzyme (ACE) inhibitors, calcineurin inhibitors, radiocontrast media, and cytostatics are the most important drugs to indicate AKI as significant risk factor in children. Direct pathophysiological mechanisms of nephrotoxicity include constriction of intrarenal vessels, acute tubular necrosis, acute interstitial nephritis, and-more infrequently-tubular obstruction. Furthermore, AKI may also be caused indirectly by rhabdomyolysis. Frequent therapeutic measures consist of avoiding dehydration and concomitant nephrotoxic medication, especially in children with preexisting impaired renal function.

Progression from acute kidney injury to chronic kidney disease: a pediatric perspective

Although emerging evidence indicates that the incidence of both acute kidney injury (AKI) and chronic kidney disease (CKD) in children is rising and the etiologies are dramatically changing, relatively little is currently known regarding the potential for transition from AKI to CKD. In both situations, early intervention can significantly improve the dismal prognosis. However, the lack of a uniform AKI definition and the paucity of early, predictive biomarkers have impaired our ability diagnose AKI early to institute potentially effective therapies in a timely manner. Fortunately, recent data has validated a multidimensional AKI classification system for children. In addition, the application of innovative technologies has identified candidates that are emerging as early biomarkers of both AKI and CKD. These include neutrophil gelatinase-associated lipocalin, liver-type fatty acid-binding protein, and kidney injury molecule-1. Studies to validate the sensitivity and specificity of these biomarkers in clinical samples from large cohorts and from multiple clinical situations are currently in progress, facilitated by the development of commercial tools for the reproducible measurement of these biomarkers across different laboratories.

Pharmacological targeting of C5a receptors during organ preservation improves kidney graft survival

Cadaveric renal transplants suffer frequently from delayed graft function, which is associated with increased risk for long-term graft survival loss. One-third of kidney grafts that are stored in current organ preservation solutions experience delayed graft function, demonstrating the urgent need for improvement. Although ischaemic graft injury is complex in nature, complement activation is considered important to the process. Here we show that pharmacological targeting of the complement 5a receptor (C5aR) during cold ischaemia has a protective effect on early kidney graft survival, inflammation and apoptosis in a mouse model of syngeneic kidney transplantation. Graft survival of kidneys that were stored in University of Wisconsin solution in the presence of a C5aR antagonist increased from 29% to 57%. Increased graft survival was associated with less tubular damage and apoptosis, protection from sustained C5aR expression and decreased production of tumour necrosis factor-alpha and macrophage inflammatory protein-2. In a translational approach, we determined C5aR expression in paediatric living-related and cadaveric allografts. C5aR expression was significantly higher in all compartments of kidneys from cadaveric compared with kidneys from living-related donors. C5aR expression in cadaveric kidneys correlated positively with cold ischaemia time, renal dysfunction and the frequency of apoptotic tubular cells, suggesting a novel role for C5a in delayed graft function pathogenesis. Supplementing organ preservation solutions with C5aR inhibitors may improve early graft function following cadaveric kidney transplantation.

Poly (ADP-ribose) polymerase as a potential target for the treatment of acute renal injury caused by lipopolysaccharide

Recent studies have clearly reported that there is a relationship between endotoxemia and acute renal injury. The aim of this study was to investigate whether treatment with the new potent PARP inhibitor PJ34 could prevent the acute renal injury induced by lipopolysaccharide (LPS). Endotoxemia was induced by LPS injection (10 mg/kg, i.v.). LPS increased blood urea nitrogen (BUN) levels from 22 +/- 0.54 mg/dL to 45.7 +/- 5.79 mg/dL (p < 0.05). The plasma creatinine levels were 0.38 +/- 0.02 mg/dL and 0.47 +/- 0.03 mg/dL for the control and LPS groups, respectively. In addition, urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG, a marker of renal tubular damage) was increased after LPS injection. By light microscopy, structural renal damage was observed in the LPS-treated group. However, PJ34 treatment (10 mg/kg, i.p.) attenuated LPS-induced renal injury, as indicated by plasma BUN and creatinine levels, urinary NAG excretion, and renal histology. These results indicated that the overactivation of the PARP pathway may have a role in LPS-induced renal impairment. Hence, pharmacological inhibition of this pathway might be an effective intervention to prevent endotoxin-induced acute renal injury.

Risk factors of acute renal failure in critically ill children: A prospective descriptive epidemiological study

OBJECTIVE

Acute renal failure is a serious condition in critically ill patients, but little literature is available on acute renal failure in critically ill children. The aim of the study was to determine incidence rate, identify risk factors, and describe the clinical outcome of acute renal failure in the pediatric intensive care unit (PICU).

DESIGN

Prospective, descriptive study.

SETTING

A tertiary PICU.

PATIENTS

Patients were 1,047 consecutively admitted children over a 1-yr period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Acute renal failure was defined as doubling of baseline serum creatinine. A comparison between patients with acute renal failure and without acute renal failure was carried out, and the risk factors playing a significant role in the manifestation of acute renal failure were analyzed. There were 985 cases included in the study, with the incidence rate of acute renal failure in PICU being 4.5%. The most common PICU admission diagnoses in acute renal failure cases were hemolytic uremic syndrome (18.2%), oncologic pathologies (18.2%), and cardiac surgery (11.4%). Significant risk factors for acute renal failure following multivariate analysis were thrombocytopenia (odds ratio, 6.3; 95% confidence interval, 2.5, 16.2), age >12 yrs (odds ratio, 4.9; 95% confidence interval, 1.9, 13), hypoxemia (odds ratio, 3.2; 95% confidence interval, 1.3, 8.0), hypotension (odds ratio, 3.0; 95% confidence interval, 1.2, 7.5), and coagulopathy (odds ratio, 2.7; 95% confidence interval, 1.3, 5.6). The mortality rate was estimated to be higher in patients with acute renal failure compared with patients without acute renal failure (29.6% vs. 2.3%, p < .001).

CONCLUSIONS

Although not frequent in the PICU, acute renal failure is associated with a significant increase in mortality. The risk factors of acute renal failure are multiple and are often present before PICU admission. A multiple-center study is planned with the intention to confirm these results.

Increasing resistance of tubular epithelial cells to apoptosis by shRNA therapy ameliorates renal ischemia-reperfusion injury

Renal tubular epithelial cells (TEC) die by apoptosis or necrosis in renal ischemia-reperfusion injury (IRI). Fas/Fas ligand-dependent fratricide is critical in TEC apoptosis, and Fas promotes renal IRI. Therefore, targeting Fas or caspase-8 may have therapeutic potential for renal injury in kidney transplant or failure. RNA silencing by short hairpin RNA (shRNA) is a novel strategy to down-regulate protein expression. Using this approach, silencing of Fas or caspase-8 by shRNA to prevent TEC apoptosis and IRI was evaluated. IRI was induced by renal artery clamping for 45 or 60 min at 32 degrees C in uninephrectomized C57BL/6 mice. Here, we showed that Fas or pro-caspase-8 expression was significantly knocked down in TEC by stable expression of shRNA, resulting in resistance to apoptosis induced by superoxide, IFN-gamma/TNF-alpha and anti-Fas antibody. Inferior vena cava delivery of pHEX-small interfering RNA targeting Fas or pro-caspase-8 resulted in protection of kidney from IRI, indicated by reduction of renal tubular injury (necrosis and apoptosis) and serum creatinine or blood urea nitrogen. Our data suggest that shRNA-based therapy targeting Fas and caspase-8 in renal cells can lead to protection of kidney from IRI. Attenuation of pro-apoptotic proteins using genetic manipulation strategies such as shRNA might represent a novel strategy to promote kidney allograft survival from rejection or failure.

Pediatric acute kidney injury: it's time for real progress

Mortality and morbidity from acute renal failure has not improved in pediatric or adult patients over the past 40 years. This lack of improvement stems from varied definitions for acute renal failure (ARF), changes in ARF epidemiology, and the reliance on changes in serum creatinine for ARF diagnosis. Significant research has occurred in the past 5 years to standardize ARF definitions, recognize ARF earlier, discover urinary biomarkers of early renal insult, and more optimally manage patients with ARF. As a result, changes in nomenclature from ARF to acute kidney injury and earlier institution of renal replacement therapy may lead to improvements in patient outcome. The aim of this editorial is to provide a description of the state of the art in pediatric ARF diagnosis and management by highlighting recent significant clinical and research progress.

3-5 year longitudinal follow-up of pediatric patients after acute renal failure

Few data exist regarding the long-term sequelae of acute renal failure (ARF), and these studies are limited to a few renal conditions. We aim to assess the 3-5-year survival and incidence of renal injury in children who previously developed ARF of varying causes. We queried parents, physicians, and hospital/state vital statistics records to find patient survival in 174 children who previously had ARF and survived to hospital discharge. We assessed the following in 29 children for residual renal injury: (a) microalbuminuria, (b) glomerular filtration rate (GFR) by Schwartz formula, (c) hypertension, and (d) hematuria. The 3-5-year survival of children with ARF who survived to hospital discharge was 139/174 (79.9%). Most deaths (24/35 (68.5%)) occurred within 12 months after initial hospitalization. Combining those who died during initial hospitalization and in subsequent 3-5 years, the overall survival rate was 139/245 (56.8%). In all, 16 children progressed to end-stage renal disease; thus, renal survival was 127/173 (91%). Those with primary renal/urologic conditions had lower renal survival than others (24/35 (68.6%) vs 134/139 (96.4%); P<0.0001). Among the 29 patients assessed for long-term sequelae at 3-5 years, 17/29 (59%) subjects had at least one sign of renal injury; microalbuminuria (n=9), hyperfiltration (n=9), decreased GFR (n=4), and hypertension (n=6). A pediatric nephrologist was involved in care of only 6/17 (35%) with chronic renal injury. Patients have high risks of ongoing residual renal injury and death after ARF; therefore, periodic evaluation after the initial insult is necessary.

Prognosis in critically ill children requiring continuous renal replacement therapy

We performed an observational prospective study in 53 critically ill children to analyze the prognostic factors of children requiring continuous renal replacement therapy. Pediatric index of mortality (PIM), pediatric risk of mortality score (PRISM), multi-organ failure score, serum lactate levels, blood pressure, vasoactive drugs, renal function and characteristics of renal replacement therapy were analyzed. The mortality was 32.1%, with multi-organ failure being the most frequent cause of death (59%). The children who died presented a significantly lower blood pressure and required more doses of vasoactive drugs, dopamine and epinephrine than did the survivors. The PRISM and PIM scores and the serum lactate levels and the number of organs suffering failure were significantly higher in the patients who died than in the survivors. However, the PRISM and PIM scores underestimated the risk of mortality. The age, sex, urea and creatinine levels, type of pump and volume of ultrafiltrate did not affect the prognosis. The association of a mean BP<55 mmHg and epinephrine dose >0.6 mug/kg/min was predictive of mortality in 76% of the patients. We conclude that the prognosis in children requiring renal replacement therapy depends on the severity of the clinical state at the time of starting therapy, principally on the hemodynamic situation.

Pediatric ARF epidemiology at a tertiary care center from 1999 to 2001

BACKGROUND

Previous epidemiological data for pediatric patients with acute renal failure (ARF) predate current intensive care unit (ICU) technology and practice, and do not reflect newer disease therapies for bone marrow, hepatic, and cardiac transplantation and congenital heart disease surgery.

METHODS

We conducted a retrospective review of 254 ARF episodes in 248 children discharged from a tertiary referral center, Texas Children's Hospital (Houston, TX), between January 1998 and June 2001 to update current pediatric ARF epidemiological characteristics.

RESULTS

The most common causes of ARF were renal ischemia (21%), nephrotoxic medications (16%), and sepsis (11%). Primary renal diseases accounted for only 17 cases (7%), and hemolytic uremic syndrome accounted for only 3 cases. Overall ARF survival for the entire cohort was 176 of 254 patients (70%), whereas 110 of 185 patients (60%) requiring ICU admission and 43 of 77 patients (56%) receiving renal replacement therapy survived.

CONCLUSION

These current pediatric ARF data show that pediatric ARF epidemiological characteristics have changed from primary renal disease to renal involvement secondary to other systemic illness. Longitudinal data from this cohort are underway to determine the long-term sequelae of pediatric ARF.

Retrospective analysis on Chinese patients diagnosed with acute renal failure hospitalized during the last decade (1994-2003)

OBJECTIVES

To investigate the epidemiology, diagnosis and prognosis of acute renal failure (ARF) in hospitalized Chinese during the last decade.

METHODS

The diagnosis of patients with ARF in Peking University Third Hospital from January 1994 to December 2003 was reconfirmed and the data of epidemiology, etiology and prognosis were analyzed.

RESULTS

Only 209 discharged cases were diagnosed with ARF and all were reconfirmed. Two peak occurrences were found at ages of 35-45 and 60-80 with a male predominance of approximately 59.7%. Patients diagnosed with ARF accounted for 1.19 per thousand of the admissions in the same period and increased significantly in the last 5 years (p = 0.038). The creatinine level at diagnosis was 345.8 +/- 122.6 micromol/l and had no significant change (p > 0.05). The percent of hospital-acquired ARF (HA-ARF) demonstrated a significant increase in 1999-2003 compared to 1994-1998 (p = 0.008). Intrarenal ARF accounted for 73.69% and was multifactorial, with drugs, infections and operations as leading causes. Renal biopsy was performed in 37.32% (78/209) with 53.84% (42/78) having acute interstitial nephritis. Maintenance dialysis was discontinued in 46.41% because their renal function completely or partially recovered. The overall mortality was 37.91% without improvement over time. The mortality was 6.25% for patients in nephrology department, but 65.51% in ICU (p < 0.001), and was 21.6% for patients in community-acquired ARF (CA-ARF), but 63.1% in HA-ARF (p < 0.001).

CONCLUSIONS

During the past 10 years, the number of patients diagnosed with ARF has been rising in hospitalized Chinese. HA-ARF was the major source, and infections, drugs and operations were the leading causes. The diagnosis and prognosis of acute renal failure did not improve much in this population over the decade studied.

Poly(ADP-ribose) polymerase-mediated cell injury in acute renal failure

Acute Renal Failure (ARF) is the most costly kidney disease in hospitalized patients and remains as a serious problem in clinical medicine. The mortality rate among ARF patients remains around 50% and no pharmaceutical agents are currently available to improve its clinical outcome. Although several successful therapeutic approaches have been developed in animal models of the disease, translation of the results to clinical ARF remains elusive. Understanding the cellular and molecular mechanisms of vascular and tubular dysfunction in ARF is important for developing acceptable therapeutic interventions. Following an ischemic episode, cells of the affected nephron undergo necrotic and/or apoptotic cell death. Necrotic cell death is widely considered to be a futile process that cannot be modulated by pharmacological means as opposed to apoptosis. However, recent reports from various laboratories including ours indicate that inhibition or absence of poly(ADP)-ribose polymerase (PARP), one of the molecules involved in cell death, provides remarkable protection in disease models such as stroke, myocardial infarction and renal ischemia which are characterized predominantly by necrotic type of cell death. Overactivation of PARP in conditions such as ischemic renal injury leads to cellular depletion of its substrate NAD+ and consequently ATP. The severely compromised cellular energetic state induces acute cell injury and diminishes renal functions. PARP activation also enhances the expression of proinflammatory agents and adhesion molecules in ischemic kidneys. Pharmacological inhibition and gene ablation of PARP-1 decreased energy depletion, inflammatory response and improved renal functions in the setting renal ischemia/reperfusion injury. The biochemical pathways and the cellular and molecular mechanisms mediated by PARP-1 activation in eliciting the energy depletion and inflammatory responses in ischemic kidney are not fully elucidated. Dissecting the molecular mechanisms by which PARP activation contributes to oxidant-induced cell death will provide new strategies to interfere in those pathways to modulate cell death in renal ischemia. The current review evaluates the experimental evidences in animal and cell culture models implicating PARP as a pathophysiological modulator of acute renal failure with particular emphasis on ischemic renal injury.

Overview of pediatric renal replacement therapy in acute renal failure

The disease spectrum leading to pediatric renal replacement therapy (RRT) provision has broadened over the last decade. In the 1980s, intrinsic renal disease and burns constituted the most common pediatric acute renal failure etiologies. More recent data demonstrate that pediatric acute renal failure (ARF) most often results from complications of other systemic diseases, resulting from advancements in congenital heart surgery, neonatal care, and bone marrow and solid organ transplantation. In addition, RRT modality preferences to treat critically ill children have shifted from peritoneal dialysis to continuous renal replacement therapy (CRRT) as a result of improvements in CRRT technologies. Currently, multicenter prospective outcome studies for critically ill children with ARF are sorely lacking. The aims of this article are to review the pediatric specific causes necessitating renal replacement therapy provision, with an emphasis on emerging practice patterns with respect to modality and the timing of treatment, and to focus upon the application of the different renal replacement therapy modalities and assessment of the outcome of children with ARF who receive renal replacement therapy.

Renal failure and renal replacement therapy

Continuous renal replacement therapy is an effective means for fluid and solute management in ARF/MOSF. Prospective studies have examined issues of anticoagulation, the impact of replacement/dialysis, the effects of bicarbonate-versus lactate-based solutions, and nutritional and medication clearance. Speculation and bias exists concerning when and for what indications CRRT should be initiated. Many clinicians, supported by data from Ronco and Goldstein, would contest that early institution is better if the risks (eg, access, anticoagulation) are minimal and the possible benefits are maximal. The authors, examining the issues as an intensivist and as a nephrologist, believe that early institution, aggressive replacement/dialysis, and use of citrate-based replacement fluids provide substantive advantages. With the advent of Ronco's recent data on sepsis managed with filtration and plasma absorption, the indication for use of CRRT in MOSF may become more evident regardless of the presence or absence of ARF.

Outcomes research in acute renal failure

Acute renal failure (ARF) is associated with morbidity and mortality in excess of 50% in the intensive care unit (ICU) setting. A variety of outcome measures have been described in published reports of ARF, however, the studies often do not distinguish between clinical outcomes and surrogate endpoints. Multiple factors can influence these outcomes, including variations in practice. It is important to be aware of the potential effects of these factors when clinical trials are planned and executed for ARF patients. For any intervention trial, knowledge of the natural history of the disease and process of care informs the design and conduct of the trial. Standardization of a definition for ARF and of the criteria for initiation, frequency, duration, and withdrawal of dialysis support would be of great benefit. This article provides a critical appraisal of outcomes research in ARF and describes an approach for selecting appropriate endpoints for future clinical research in ARF.