Hospital-acquired acute renal failure

Fluid management in acute kidney injury: from evaluating fluid responsiveness towards assessment of fluid tolerance

Despite the widespread use of intravenous fluids in acute kidney injury (AKI), solid evidence is lacking. Intravenous fluids mainly improve AKI due to true hypovolaemia, which is difficult to discern at the bedside unless it is very pronounced. Empiric fluid resuscitation triggered only by elevated serum creatinine levels or oliguria is frequently misguided, especially in the presence of fluid intolerance syndromes such as increased extravascular lung water, capillary leak, intra-abdominal hypertension, and systemic venous congestion. While fluid responsiveness tests clearly identify patients who will not benefit from fluid administration (i.e. those without an increase in cardiac output), the presence of fluid responsiveness does not guarantee that fluid therapy is indicated or even safe. This review calls for more attention to the concept of fluid tolerance, incorporating it into a practical algorithm with systematic venous Doppler ultrasonography assessment to use at the bedside, thereby lowering the risk of detrimental kidney congestion in AKI.

Predictors of Mortality in Patients with Acute Renal Failure

Mortality associated with acute renal failure (ARF) remains high despite of developments in therapy strategies and definition of different prognostic factors. Therefore, this study focused on to define new prognostic factors and especially regional characteristics of the ARF patients. One hundred fifteen ARF patients, diagnosed from November 1998 to May 2003, were included to this prospective and observational study. Clinical features, laboratory parameters, Acute Physiology and Chronic Health Evaluation (APACHE) III scores and co-morbid conditions of the patients were examined. Clinical and laboratory data, and APACHE III scores were recorded at the first nephrology consult day. Thirty of the patients (26%) died. APACHE III scores, presence and the total number of co-morbid conditions and serum albumin levels at the time of first nephrology consultation were found as independent predictors of mortality. There was a negative correlation between APACHE III scores and serum albumin levels. Not only increased APACHE III score and presence of co-morbid conditions but also low serum albumin level was found as the predictors of mortality. However, only serum albumin level is seen as modifiable prognostic factor among these parameters. Therefore, further studies are necessary to determine the causes of hypoalbuminemia in patients with ARF and the effect of it’s effective treatment on patients outcome.

Kidney ischemia and reperfunsion syndrome: effect of lidocaine and local postconditioning

Objective:

to evaluate the effects of blocking the regulation of vascular tone on the ischemia and reperfusion syndrome in rats through the use of lidocaine in the postconditioning technique.

Methods:

we randomized 35 rats into seven groups of five animals: Group 1- Control; Group 2- Ischemia and Reperfusion; Group 3- Ischemia, Reperfusion and Saline; Group 4- Ischemic Postconditioning; Group 5- Ischemic Postconditioning and Saline; Group 6- Lidocaine; Group 7- Ischemic Postconditioning and Lidocaine. Except for the control group, all the others were submitted to renal ischemia for 30 minutes. In postconditioning groups, we performed ischemia and reperfusion cycles of five minutes each, applied right after the main ischemia. In saline and lidocaine groups, we instilled the substances at a rate of two drops per minute. To compare the groups, we measured serum levels of urea and creatinine and also held renal histopathology.

Results:

The postconditioning and postconditioning + lidocaine groups showed a decrease in urea and creatinine values. The lidocaine group showed only a reduction in creatinine values. In histopathology, only the groups submitted to ischemic postconditioning had decreased degree of tubular necrosis.

Conclusion:

Lidocaine did not block the effects of postconditioning on renal ischemia reperfusion syndrome, and conferred better glomerular protection when applied in conjunction with ischemic postconditioning.

Objetivo:

avaliar os efeitos do bloqueio da regulação do tônus vascular por meio do uso da lidocaína na técnica de pós-condicionamento isquêmico na síndrome de isquemia e reperfusão renal em ratos.

Métodos:

trinta e cinco ratos foram randomizados em sete grupos de cinco animais: Grupo 1- Controle; Grupo 2- Isquemia e Reperfusão; Grupo 3- Isquemia, Reperfusão e Solução Salina; Grupo 4- Pós-condicionamento Isquêmico; Grupo 5- Pós-condicionamento Isquêmico e Solução Salina; Grupo 6- Lidocaína; Grupo 7- Pós-condicionamento Isquêmico e lidocaína. Com exceção do grupo controle, todos os demais foram submetidos à isquemia renal de 30 minutos. Nos grupos de pós-condicionamento, foi realizado o ciclo de isquemia e reperfusão de cinco minutos cada, aplicado logo após a isquemia principal. Nos grupos salina e lidocaína foram instiladas as substâncias numa taxa de duas gotas por minuto. Para comparar os grupos, foram dosados os níveis séricos de ureia e creatinina e análise histopatológica renal.

Resultados:

os grupos pós-condicionamento e pós-condicionamento + lidocaína apresentaram uma redução nos valores de ureia e creatinina. O grupo lidocaína apresentou apenas uma redução nos valores de creatinina. Na análise histopatológica, apenas os grupos submetidos ao pós-condicionamento isquêmico apresentaram redução do grau de necrose tubular.

Conclusão:

a lidocaína não bloqueou os efeitos do pós-condicionamento na síndrome de isquemia e reperfusão renal, mas conferiu melhor na proteção glomerular quando aplicada em conjunto com o pós-condicionamento isquêmico.

Perconditioning combined with postconditioning on kidney ischemia and reperfusion

Purpose:

To evaluate if combination of perconditioning and postconditioning provides improved renal protection compared to perconditioning alone in a model of renal reperfusion injury.

Methods:

Thirty rats were assigned into 6 groups: normality; sham; ischemia and reperfusion; postconditioning; perconditioning; perconditioning + postconditioning. Animals were subjected to right nephrectomy and left renal ischemia for 30 minutes. Postconditioning consisted of 3 cycles of 5 min renal perfusion followed by 5 min of renal ischemia after major ischemic period. Perconditioning consisted of 3 cycles of 5 min hindlimb ischemia followed by 5 min of hindlimb perfusion contemporaneously to renal major ischemic period. After 24 hours, kidney was harvested and blood collected to measure urea and creatinine.

Results:

Perconditioning obtained better values for creatinine and urea level than only postconditioning (p<0.01); performing both techniques contemporaneously had no increased results (p>0.05). Regarding tissue structure, perconditioning was the only technique to protect the glomerulus and tubules (p<0.05), while postconditioning protected only the glomerulus (p<0.05). Combination of both techniques shows no effect on glomerulus or tubules (p>0.05).

Conclusions:

Perconditioning had promising results on ischemia and reperfusion induced kidney injury, enhanced kidney function and protected glomerulus and tubules. There was no additive protection when postconditioning and perconditioning were combined.

MiR-30c regulates cisplatin-induced apoptosis of renal tubular epithelial cells by targeting Bnip3L and Hspa5

As a common anticancer drug, cisplatin has been widely used for treating tumors in the clinic. However, its side effects, especially its nephrotoxicity, noticeably restrict the application of cisplatin. Therefore, it is imperative to investigate the mechanism of renal injury and explore the corresponding remedies. In this study, we showed the phenotypes of the renal tubules and epithelial cell death as well as elevated cleaved-caspase3- and TUNEL-positive cells in rats intraperitoneally injected with cisplatin. Similar cisplatin-induced cell apoptosis was found in HK-2 and NRK-52E cells exposed to cisplatin as well. In both models of cisplatin-induced apoptosis in vivo and in vitro, quantitative PCR data displayed reductions in miR-30a-e expression levels, indicating that miR-30 might be involved in regulating cisplatin-induced cell apoptosis. This was further confirmed when the effects of cisplatin-induced cell apoptosis were found to be closely correlated with alterations in miR-30c expression, which were manipulated by transfection of either the miR-30c mimic or miR-30c inhibitor in HK-2 and NRK-52E cells. Using bioinformatics tools, including TargetScan and a gene expression database (Gene Expression Omnibus), Adrb1, Bnip3L, Hspa5 and MAP3K12 were predicted to be putative target genes of miR-30c in cisplatin-induced apoptosis. Subsequently, Bnip3L and Hspa5 were confirmed to be the target genes after determining the expression of these putative genes following manipulation of miR-30c expression levels in HK-2 cells. Taken together, our current experiments reveal that miR-30c is certainly involved in regulating the renal tubular cell apoptosis induced by cisplatin, which might supply a new strategy to minimize cisplatin-induced nephrotoxicity.

Incidence, Outcomes, and Risk Factors of Community-Acquired and Hospital-Acquired Acute Kidney Injury: A Retrospective Cohort Study

The disease burden and outcomes of community-acquired (CA-) and hospital-acquired acute kidney injury (HA-AKI) are not well understood. The aim of the study was to investigate the incidence, outcomes, and risk factors of AKI in a large Taiwanese adult cohort.This retrospective cohort study examined 734,340 hospital admissions from a group of hospitals within an organization in Taiwan between January 1, 2010 and December 31, 2014. Patients with AKI at discharge were classified as either CA- or HA-AKI based on the RIFLE (risk, injury, failure, loss of function, end stage of kidney disease) classification criteria. Outcomes were in-hospital mortality, dialysis, recovery of renal function, and length of stay. Risks of developing AKI were determined using multivariate logistic regression based on demographic and baseline clinical characteristics and nephrotoxin use before admission.AKI occurred in 1.68% to 2% hospital discharges among adults without and with preexisting chronic kidney disease (CKD), respectively. The incidence of CA-AKI was 17.25 and HA-AKI was 8.14 per 1000 admissions. The annual rate of CA-AKI increased from 12.43 to 19.96 per 1000 people, but the change in HA-AKI was insignificant. Comparing to CA-AKI, those with HA-AKI had higher levels of in-hospital mortality (26.07% vs 51.58%), mean length of stay (21.25 ± 22.35 vs 35.84 ± 34.62 days), and dialysis during hospitalization (1.45% vs 2.06%). Preexisting systemic diseases, including CKD were associated with increased risks of CA-AKI, and nephrotoxic polypharmacy increased risk of both CA- and HA-AKI.Patients with HA-AKI had more severe outcomes than patients with CA-AKI, and demonstrated different spectrum of risk factors. Although patients with CA-AKI with better outcomes, the incidence increased over time. It is also clear that optimal preventive and management strategies of HA- and CA-AKI are urgently needed to limit the risks in susceptible individuals.

National Veterans Health Administration inpatient risk stratification models for hospital-acquired acute kidney injury

OBJECTIVE

Hospital-acquired acute kidney injury (HA-AKI) is a potentially preventable cause of morbidity and mortality. Identifying high-risk patients prior to the onset of kidney injury is a key step towards AKI prevention.

MATERIALS AND METHODS

A national retrospective cohort of 1,620,898 patient hospitalizations from 116 Veterans Affairs hospitals was assembled from electronic health record (EHR) data collected from 2003 to 2012. HA-AKI was defined at stage 1+, stage 2+, and dialysis. EHR-based predictors were identified through logistic regression, least absolute shrinkage and selection operator (lasso) regression, and random forests, and pair-wise comparisons between each were made. Calibration and discrimination metrics were calculated using 50 bootstrap iterations. In the final models, we report odds ratios, 95% confidence intervals, and importance rankings for predictor variables to evaluate their significance.

RESULTS

The area under the receiver operating characteristic curve (AUC) for the different model outcomes ranged from 0.746 to 0.758 in stage 1+, 0.714 to 0.720 in stage 2+, and 0.823 to 0.825 in dialysis. Logistic regression had the best AUC in stage 1+ and dialysis. Random forests had the best AUC in stage 2+ but the least favorable calibration plots. Multiple risk factors were significant in our models, including some nonsteroidal anti-inflammatory drugs, blood pressure medications, antibiotics, and intravenous fluids given during the first 48 h of admission.

CONCLUSIONS

This study demonstrated that, although all the models tested had good discrimination, performance characteristics varied between methods, and the random forests models did not calibrate as well as the lasso or logistic regression models. In addition, novel modifiable risk factors were explored and found to be significant.

Acute kidney injury after open ventral hernia repair: an analysis of the 2005-2012 ACS-NSQIP datasets

PURPOSE

Acute kidney injury (AKI) is a serious postoperative complication, negatively impacting mortality rates, extending length of stay, and raising hospital costs. The purpose of this study was to examine AKI following open ventral hernia repair (OVHR) using a large, heterogeneous database to determine the incidence and identify risk factors for this complication.

METHODS

Using the 2005-2012 ACS-NSQIP database, patients undergoing open ventral hernia repair were identified by CPT codes. Patients with acute kidney injury within 30 days of surgery were compared to controls by multivariate logistic regression across preoperative and intraoperative characteristics.

RESULTS

Of 48,629 open ventral hernia repair patients identified in the dataset, AKI developed in 1.4% (681 patients). Multivariate logistic regression determined a number of factors associated with AKI. These include WHO Class III obesity (OR = 2.57, p < 0.001), history of cardiovascular disease (OR = 1.81, p < 0.001), diabetes (OR = 1.29, p = 0.028), hypoalbuminemia (OR = 1.42, p = 0.004), and chronic kidney disease (for a baseline GFR of 60-89 mL/min/1.73 m2, OR = 1.62, p = 0.001; for 30-59 mL/min/1.73 m2, OR = 2.25, p < 0.001; for 15-29 mL/min/1.73 m2, OR = 4.96, p < 0.001). Intraoperative factors include prolonged operative time (for ≥1 SD above the mean, OR = 1.68, p = 0.002; for ≥2SD above the mean, OR = 2.76, p < 0.001) and intraoperative transfusion (OR = 2.44, p < 0.001).

CONCLUSIONS

Patients with a history of obesity, chronic kidney disease, cardiovascular history, diabetes, and hypoalbuminemia are at increased risk for AKI when undergoing OVHR. Intraoperative variables such as prolonged operative times and blood transfusions may also suggest increased risk. Preoperative identification of patients with these characteristics and perioperative hemodynamic stabilization are important first steps to minimize this complication.

Evaluation of acute kidney injury in the hospital setting

Acute kidney injury (AKI) is becoming more prevalent in the hospital setting and is associated with the worst prognostic outcomes, including increased mortality. Many different factors contribute to the development of AKI in hospitalized patients, including medications, older age, sepsis, and comorbid conditions. Correct evaluation and management of AKI requires investigation and understanding of important causative factors for each of the 3 pathophysiologic categories of renal failure. Preventative efforts rely on prompt recognition of AKI while avoiding iatrogenic insults in the hospital setting.

Timing of acute kidney injury--does it matter? A single-centre experience from the United Kingdom

BACKGROUND

Acute kidney injury (AKI) requiring renal replacement therapy (RRT) is associated with high mortality and long-term dependence on RRT. However, there is limited information about the difference in outcome between patients who develop AKI in the community (c-AKI), and those who develop AKI in hospital (h-AKI).

AIM

Identify differences in short- and long-term outcomes between patients admitted with c-AKI and h-AKI who require intermittent haemodialysis, and to identify factors that predict poor outcome.

DESIGN & METHODS

Single-centre, retrospective analysis of 306 patients with AKI who received intermittent haemodialysis between 2009 and 2011.

FOLLOW-UP

six months. Primary endpoints: patient and renal survival. Secondary endpoints: time on dialysis, length of hospital stay, and admission to the intensive care unit (ICU).

RESULTS

Survival for patients in the h-AKI group was significantly lower, at 42.9% (compared to 72%). They had a significantly longer length of stay. However, at 6-month follow-up, the survival benefit of the c-AKI group was no longer significant. Patients with h-AKI were more likely to be dialysis independent at discharge and six months although this result did not reach statistical significance. Independent predictors of survival to discharge within the entire group included: renal/post-renal causes of AKI, younger age, pre-existing diabetes, and c-AKI. The only independent predictor for RRT dependence at discharge and six months was pre-existing chronic kidney disease.

CONCLUSIONS

h-AKI is associated with high mortality and longer hospital stays during the acute admission. However, h-AKI patients who survive are more likely to be independent of RRT at discharge and follow-up.

Solute carrier transporter and drug-related nephrotoxicity: the impact of proximal tubule cell models for preclinical research

INTRODUCTION

The final excretion step of several drugs is facilitated by membrane transporters of the Solute carrier (SLC) family expressed in the proximal tubules of the kidney. Membrane transporters contribute substantially to the pharmacokinetic profile of drugs and play important roles in drug-induced nephrotoxicity. Different cell models have been applied as tools for the assessment of nephrotoxic effects caused by drugs.

AREAS COVERED

This review gives an overview over clinically relevant SLC transporters involved in the renal elimination of drug agents and their specific role in drug-induced nephrotoxicity. Most widely applied cell models are described and their advantages and limitations are outlined.

EXPERT OPINION

In vitro cell culture models (e.g., continuous and primary renal cell lines, polarized cell monolayers) represent valuable tools for early assessment of the nephrotoxic potential of drugs. Since SLC transporters contribute to drug excretion in a large part, in vitro cell culture models might be very helpful to study transport pathways and/or potential drug-drug interactions at an early stage of the drug development process to predict nephrotoxic effects.

Effect of novel vitamin D receptor activator paricalcitol on renal ischaemia/reperfusion injury in rats

INTRODUCTION

Despite the developments in modern medicine, acute renal injury is still a challenging and common health problem. It is well known that ischaemia and reperfusion takes place in pathological mechanisms. Efforts to clarify the pathophysiology and interventions to improve outcomes are essential. Our study aimed to investigate whether the prophylactic use of paricalcitol is beneficial in renal ischaemia/reperfusion (I/R) injury.

METHODS

Twenty-four Wistar albino rats were assigned randomly to four groups. Right nephrectomies were performed at the time of renal arterial clamping. Sham surgery was performed on the rats in group 1. For the rats in group 2, the left renal artery was clamped for 45 minutes. The rats in group 3 received paricalcitol for seven days (0.2μg/kg/day); following this, a right nephrectomy and left renal arterial clamping were not performed. The rats in group 4 received paricalcitol for seven days (0.2μg/kg/day); following this, a right nephrectomy and left renal arterial clamping for 45 minutes were performed. Tissue thiobarbituric acid reactive substances (TBARS), superoxide dismutase, sulfhydryl groups as well as nitric oxide metabolites, serum urea and creatinine levels were measured for all four groups.

RESULTS

In group 4, there were some improvements in terms of TBARS, nitrite, nitrate, superoxide dismutase and creatinine levels. In the histopathological evaluation, paricalcitol therapy improved tubular necrosis and medullar congestion but there was no significant difference in terms of tubular cell swelling, cellular vacuolisation or general damage. Immunohistopathological examination revealed lower scores for vascular endothelial growth factor in the group 4 rats than in group 2.

CONCLUSIONS

Paricalcitol therapy improved renal I/R injury in terms of serum and histopathological parameters. These potential beneficial effects need to be further investigated.

Pediatric Sepsis - Part I: "Children are not small adults!"

The recognition, diagnosis, and management of sepsis remain among the greatest challenges in pediatric critical care medicine. Sepsis remains among the leading causes of death in both developed and underdeveloped countries and has an incidence that is predicted to increase each year. Unfortunately, promising therapies derived from preclinical models have universally failed to significantly reduce the substantial mortality and morbidity associated with sepsis. There are several key developmental differences in the host response to infection and therapy that clearly delineate pediatric sepsis as a separate, albeit related, entity from adult sepsis. Thus, there remains a critical need for well-designed epidemiologic and mechanistic studies of pediatric sepsis in order to gain a better understanding of these unique developmental differences so that we may provide the appropriate treatment. Herein, we will review the important differences in the pediatric host response to sepsis, highlighting key differences at the whole-organism level, organ system level, and cellular and molecular level.

Neutrophil gelatinase-associated lipocalin (NGAL) as a biomarker for early acute kidney injury

Based on information to date, although limitations in the accuracy of NGAL in predicting AKI persist, the preponderance of published studies demonstrate that NGAL, when measured in the plasma and in the urine, is a reliable biomarker for the subsequent development of clinically apparent AKI. If very early detection of AKI, via the measurement of plasma or urinary NGAL, can be followed by effective treatment to abort the development or limit the severity of AKI, and therefore decrease the rate of RRT, length of hospitalization stay, and/or mortality risk, NGAL measurement will become a critically important diagnostic tool in critical care medicine, pediatrics, and surgery.

Interaction of oxidative stress, nitric oxide and peroxisome proliferator activated receptor gamma in acute renal failure

Oxidative stress has been reported to play a critical role in the pathology of acute renal failure (ARF). An interaction between different reactive species and/or their sources have been the focus of extensive studies. The exact sources of reactive species generated in biological systems under different disease states are always elusive because they are also a part of physiological processes. Exaggerated involvement of different oxidation pathways including NAD(P)H oxidase has been proposed in different models of ARF. An interaction between oxygen species and nitrogen species has drawn extensive attention because of the deleterious effects of peroxynitrite and their possible effects on antioxidant systems. Recent advances in molecular biology have allowed us to understand glomerular function more precisely, especially the organization and importance of the slit diaphragm. Identification of slit diaphragm proteins came as a breakthrough and a possibility of therapeutic manipulation in ARF is encouraging. Transcriptional regulation of the expression of slit diaphragm protein is of particular importance because their presence is crucial in the maintenance of glomerular function. This review highlights the involvement of oxidative stress in ARF, sources of these reactive species, a possible interaction between different reactive species, and involvement of PPARgamma, a nuclear transcription factor in this process.

Specific nutritional problems in acute kidney injury, treated with non-dialysis and dialytic modalities

Patients who develop AKI, especially in the intensive care unit (ICU), are at risk of protein-energy malnutrition, which is a major negative prognostic factor in this clinical condition. Despite the lack of evidence from controlled trials of its effect on outcome, nutritional support by the enteral (preferentially) and/or parenteral route appears clinically indicated in most cases of ICU-acquired AKI, independently of the actual nutritional status of the patient, in order to prevent deterioration in the nutritional state with all its known complications. Extrapolating from data in other conditions, it seems intrinsically unlikely that starvation of a catabolic patient is more beneficial than appropriate nutritional support by an expert team with the skills to avoid the potential complications of the enteral and parenteral nutrition methodologies. By the same token, it is ethically impossible to conduct a trial in which the control group undergoes prolonged starvation. The primary goals of nutritional support in AKI, which represents a well-known inflammatory and pro-oxidative condition, are the same as those for other critically ill patients with normal renal function, i.e. to ensure the delivery of adequate nutrition, to prevent protein-energy wasting with its attendant metabolic complications, to promote wound healing and tissue repair, to support immune system function, to accelerate recovery and to reduce mortality. Patients with AKI on RRT should receive a basic intake of at least 1.5 g/kg/day of protein with an additional 0.2 g/kg/day to compensate for amino acid/protein loss during RRT, especially when daily treatments and/or high efficiecy modalities are used. Energy intake should consist of no more than 30 kcal non-protein calories or 1.3 × BEE (Basal Energy Expenditure) calculated by the Harris-Benedict equation, with ∼30-35% from lipid, as lipid emulsions. For nutritional support, the enteral route is preferred, although it often needs to be supplemented through the parenteral route in order to meet nutritional requirements.

Perioperative management of patients with renal disease

The patient who has renal disease is susceptible to many potential complications during the perioperative period. The prevention of postoperative acute renal failure (ARF), especially in patients who have existing chronic kidney disease, and management of patients who have end-stage renal disease (ESRD) who are undergoing surgery are challenging. Elimination of risk factors for ARF and early diagnosis of ARF should improve patient outcomes. For patients who have ESRD, a thorough and comprehensive evaluation is necessary to decrease morbidity and mortality associated with the end-organ damage. This article reviews the prevention of postoperative ARF and the perioperative management of patients who have ESRD who are undergoing surgery.

Hospital-acquired acute kidney injury

Acute kidney injury (AKI) is a common clinical syndrome in hospitalized patients associated with high morbidity and mortality rates. Despite several years of improvement in the medical care of the severely ill, there has been little improvement in outcome. Furthermore, effective means of preventing and treating AKI have remained elusive. Although dialysis has been the mainstay of treating AKI for > 40 years, several questions regarding its application remain unsettled, including method (continuous vs intermittent), timing, and dose. The purpose of this review is to summarize recent advances in the epidemiology and treatment of AKI in hospitalized patients.

Acute kidney injury in the elderly population

The elderly population is more prone to acute kidney injury (AKI) than younger populations. Older patients have less renal reserve because of reduced glomerular filtration rates due to anatomic/functional changes, and concomitant diseases such as hypertension, diabetes, atherosclerosis, heart failure, ischemic renal disease, and obstructive uropathy. The risk of AKI may also increase as a result of aggressive diagnostic and therapeutic procedures, which include medical agents, radiology, and surgical intervention. AKI in the elderly has a multifactorial physiopathology due to different etiologies. Studies that have specifically compared prognosis of AKI in elderly versus young over the recent years suggest that age is a predictor of long-term outcome. In most cases, the treatment of AKI is similar for all age groups. The majority of critically ill patients with AKI will eventually need renal replacement therapy (RRT). The influence of RRT on renal outcome remains a subject of intense investigation and debate. Avoiding situations that could damage the kidney is an important strategy to prevent AKI development in the elderly, besides medical and interventional therapeutics.

Does the Analysis Based on a Histological and Immunohistochemical Grading System in the Model of BDL Kidney Allow the Quantification of the Degree of Injury?

The aim of this study is to evaluate histopathological findings induced by Nomega-nitro-L-arginine methyl ester (L-NAME) and molsidomine (MOL) on the kidney of bile duct ligated rats. Forty Sprague-Dawley rats, each weighing 125 to 140 g, were included in the study. Extent of histological glomerular injury scores (GIS), arterial injury scores (AIS), and tubulointerstitial injury scores (TIS) in each animal were graded. Alpha-smooth muscle actin (alpha-SMA), tenascin, lectin (Ulex europaeus agglutinin-1), and vimentin were used to determine extent of the injury. The cholestasis was evidenced by a significant increase in the levels of serum total bilirubin in BDL rats (p < 0.01). Malondialdeyde MDA levels increased by the bile duct ligation (BDL) to 12.10 +/- 0.45. This value was significantly higher than the other groups (p < 0.01). Changes in the BDL kidney were marked at 7 days after surgery. GIS were observed to have the highest score, especially at juxtamedullary region in BDL/L-NAME rats, and AIS were also the highest score in this region. These observations were lower in BDL/MOL rats. There is a correlation between GIS and AIS scores (r = .2, p < .01). TIS revealed that BDL/L-NAME rats were significantly more damage than rats in the other groups (p<.001). MOL-treated rats showed considerably fewer lesions in the tubules and interstitium (p < .001). The tubular injuries observed in BDL and BDL/L-NAME rats were significantly attenuated by MOL treatment. Lectin was more and extensively stained in tubular epithelia of the BDL/L-NAME group than in the other (p <.05). Expression of tenascin in tubular epithelia was significantly higher in BDL and BDL/L-NAME as compared with controls (p < .01). Fibrous tissue was only observed in the BDL and BDL/L-NAME group. These areas were weakly stained with vimentin. alpha-SMA staining was more reduced in the L-NAME-treated arterioles than in BDL/MOL (p < .05). In conclusion, the analysis of cell injury based on a histological grading system in the model of BDL kidney allows the quantification of the degree of injury.

Causes and Prognosis of Nontraumatic Acute Renal Failure Requiring Dialysis in Adult Patients with and without Diabetes

Despite advanced techniques of renal replacement therapy the overall mortality of patients with ARF is still high. The majority of patients with ARF requiring dialysis are those with nontraumatic ARF. In a retrospective study we compared the causes of nontraumatic ARF, the risk factors for the development of renal failure and the mortality rates in patients with and without diabetes mellitus who received dialysis therapy in the years 1991-2000. A total of 232 patients were included in the study, 34 (14.6%) of them with and 198 patients (85.4%) without diabetes. The predominant causes of nontraumatic ARF like congestive heart failure (26.4 vs. 13.6, p < 0.05) and hypotension/hypovolemia (20.6 vs. 7.6%, p < 0.05) occurred more frequently in diabetic patients. The prevalence of sepsis (8.8 vs. 10.1%, NS), malignancy/ hypercalcemia (5.8 vs. 11.6%, NS) and other causes of nontraumatic ARF were similar in both groups. The prevalence of hepato-renal syndrome (5.8 vs. 13.6%, p < 0.05) and acute kidney graft failure (2.9 vs. 15.1%, p < 0.05) was higher in the nondiabetic individuals. Patients with diabetes showed more often chronic predictors for the onset of ARF like pre-existing hypertension (93.6 vs. 51.0%, p < 0.05), congestive heart failure (44.1 vs. 14.6%, p < 0.005), pre-existing renal insufficiency (76.4 vs. 46.9%, p < 0.05) and ACE-inhibitor therapy (32.3 vs. 9.6%, p < 0.005). Additionally, the prevalence of multiple organ failure (MOF) as prognostic factor was significantly higher in the diabetic patients (47.0 vs. 21.7%, p < 0.05). The mean number of dialyses therapy was 4.7 vs. 4.5 per patient. The overall mortality was 41.1 vs. 44.% (NS). In conclusion, the prevalence of the most common causes of nontraumatic ARF was different between the patients with and without diabetes. The diabetic individuals had more frequently predictors for the onset of ARF. The overall mortality was approximately the same in both groups.

Validation of Liano score in acute renal failure: a prospective study in Indian patients

AIM

To validate Liano score as a prognostic scoring system in acute renal failure (ARF): a prospective study in Indian patients.

PATIENTS AND METHODS

Prospective study including 100 patients over a period of 1 year, from March 2006 to July 2007. Inclusion criteria were patients with no previous renal disease or any systemic disease known to affect the kidney and who presented with acute rise (hours to days) in serum creatinine. Exclusion criteria were patients with preexisting chronic renal failure, age younger than 12 years and ultrasound of the abdomen showing contracted kidneys.

RESULTS AND CONCLUSIONS

In this study there were 68 males and 32 females. Peak incidence by age was in the fifth decade. There was no increased mortality in any age group (p = 0.278). A total of 19 patients had pre-renal ARF, 74 patients had intrinsic ARF, of which 46 were acute tubular necrosis (ATN); 7 patients had obstructive ARF. A total of 21 patients had Liano score greater than 0.9, of which 18 patients died and 3 were discharged against medical advice in a critical condition (and died later at home). Calculated sensitivity was 62.1%, specificity was 100% and positive predictive value was 100%. Sensitivity and specificity when calculated separately for intrinsic renal ARF (after excluding post renal ARF) were 60.7% and 100%, respectively. There was statistically significant correlation between Liano score and mortality (p < 0.001).

Biocompatible hemodialysis membranes for acute renal failure

BACKGROUND

Acute renal failure (ARF) is associated with substantial morbidity and mortality. Some studies have reported a survival advantage among patients dialyzed with biocompatible membranes (BCM) compared to bioincompatible membranes (BICM). These findings were not consistently observed in subsequent studies.

OBJECTIVES

To ascertain whether the use of BCM confers an advantage in either survival or recovery of renal function over the use of BICM in adult patients with ARF requiring intermittent hemodialysis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library), MEDLINE (from 1966), EMBASE (from 1980), the Mexican Index of Latin American Biomedical Journals IMBIOMED (from 1990), the Latin American and Caribbean Health Sciences Literature Database LILACS (from 1982), and reference lists of articles. Search date: January 2007

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing the use of a BCM with a BICM in patients > 18 years of age with ARF requiring intermittent hemodialysis.

DATA COLLECTION AND ANALYSIS

Two authors extracted the data independently. Cellulose-derived dialysis membranes were classified as BICM, and synthetic dialyzers were considered as BCM. The main outcomes were all-cause mortality and recovery of renal function by type of dialyzer. We further explored these outcomes according to the flux properties (high-flux or low-flux) of each of these dialyzers. A meta-analysis was conducted by combining data using a random-effects model.

MAIN RESULTS

Ten studies were included in the primary analysis of mortality, with a total of 1100 patients. None of the pooled risk ratios (RRs) reached statistical significance. The pooled RR for mortality was 0.93 (95% confidence interval (CI) 0.81 to 1.07). The overall RR for recovery of renal function, which was inclusive of 1038 patients from nine studies, was 1.09 (95% CI 0.90 to 1.31). The pooled RR for mortality by dialyzer flux property was 1.05 (95% CI 0.81 to 1.37). The pooled RR for recovery of renal function by flux property was 1.30 (95% CI 0.83 to 2.02). A meta-analysis of mortality among kidney transplant recipients was not possible, however the analysis of recovery of renal function in this patient population revealed an RR of 1.05 (95% CI 0.87 to 1.26). Results of sensitivity analyses did not differ significantly from the primary analyses.

AUTHORS' CONCLUSIONS

There is no demonstrable clinical advantage to the use of BCM versus BICM in patients with ARF who require intermittent hemodialysis.

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.

The utility of a rodent model in detecting pediatric drug-induced nephrotoxicity

A multi-age rat model was used to identify potential age-related differences in renal injury following exposure to gentamicin (GM). In this study, 10-, 25-, 40-, and 80-day-old Sprague-Dawley rats were dosed with GM at 0, 50, or 100 mg kg(-1) body weight per day (mkd) sc for 6 or 14 days. Urine samples were collected up to 72 h after initial dosing. The maximum tolerated dose was lower in 10-day-old rats than for other ages (none survived 11 days of treatment). Eighty-day-old rats given the highest dose showed a diminished rate of growth and an increase in serum creatinine, blood urea nitrogen (BUN), urinary kidney injury molecule-1 (Kim-1), and renal pathology. Ten- and 40-day-old rats given 100 mkd of GM for 6- or 14 days also had increased levels of serum BUN and Cr and renal pathology, whereas only mild renal alterations were found in 25-day-old rats. After 6 days of treatment with 100 mkd GM, significant increases in Havcr-1 (Kim-1) gene expression were detected only in 10- and 80-day-old rats. In urine samples, nuclear magnetic resonance and ultra performance liquid chromatography/mass spectrometry analysis detected changes related to GM efficacy (e.g., hippurate) and increases in metabolites related to antioxidant activity, which was greatest in the 80-day-old rats. The magnitude of the genomic, metabonomic, and serum chemistry changes appeared to correlate with the degree of nephropathy. These findings indicate that an experimental animal model that includes several developmental stages can detect age-related differences in drug-induced organ toxicities and may be a useful predictor of pediatric drug safety in preclinical studies.

Hospital-acquired and community-acquired acute renal failure in hospitalized Chinese: a ten-year review

OBJECTIVES

To investigate the difference between hospital-acquired acute renal failure (HA-ARF) and community-acquired acute renal failure (CA-ARF) in hospitalized Chinese.

METHODS

The diagnosis of ARF in Peking University Third Hospital from January 1994 to December 2003 was reconfirmed and subdivided into AC-ARF and HA-ARF. Data of epidemiology, etiology, prognosis, and associated factors were analyzed. Single-variable analysis and multivariate logistic regression analyses were performed to investigate the correlation between clinical features and prognosis respectively. Results among 205 reconfirmed CA-ARF had a predominance of 59.5%, but HA-ARF demonstrated an increase by 1.06 during the last five years (p = 0.003). In all, 70.5% CA-ARF was diagnosed in internal medicine with 45.9% in department of nephrology, whereas 59.1% HA-ARF was diagnosed in surgical department with 51.8% in ICU. Distribution difference among departments was significant (p < 0.01). Further, 90.2% CA-ARF was associated with a single factor, while 36.1% of HA-ARF had two or more causes (p < 0.01). Also, 26.5% HA-ARF and 18.9% CA-ARF was drug-associated (p > 0.05) while 24.1% HA-ARF and 12.3% CA-ARF was infection-associated (p < 0.01). HA-ARF vs. CA-ARF was 62.7% vs. 23.0% in mortality (p < 0.01), 0.54 +/- 0.24 vs. 0.27 +/- 0.18 in ATI-ISS index (p < 0.01) and 19.6 +/- 4.9 vs. 15.7 +/- 5.6 in APACHE II scores (p < 0.01). MODS and SIRS were common independent predictors with oliguria for HA-ARF and advanced age for CA-ARF, respectively.

CONCLUSIONS

In hospitalized Chinese during the last ten years, CA-ARF was still predominant with simpler cause and lower mortality, whereas HA-ARF was increasing with more complicated cause and higher mortality.

Continuous renal replacement therapy in patients following traumatic injury

In critically injured patients, the incidence of acute renal failure has been reported to occur in as many as 31% of patients. The use of CRRT modalities for patients following traumatic injuries is becoming more common, albeit slowly, and this therapy may impact upon long-term recovery of renal function and mortality. Historical studies investigating the early use of intermittent dialysis reported significant improvement in survival in patients who were dialyzed earlier and more vigorously than in control subjects. Early trauma patients also showed improved survival following war injuries when dialyzed prophylactically. Although there is a growing acceptance in favor of earlier renal replacement therapy, the published consensus and the practice in many centers has been to dialyze/filter relatively ill rather than relatively healthy patients. The R Adams Cowley Shock Trauma Center (STC) in Baltimore, Maryland, USA, admits over 8,000 trauma patients each year. Within the STC, a program of continuous renal replacement therapy was established in the early 1980's. We review both historical and current literature on the use of renal replacement therapies after traumatic injury, and suggest some future areas of investigation and indications for these modalities.

Preplaced cell division: a critical mechanism of autoprotection againstS-1,2-dichlorovinyl-l-cysteine-induced acute renal failure and death in mice

Previous studies have shown that renal injury initiated by a lethal dose of S-1,2-dichlorovinyl-l-cysteine (DCVC) progresses due to inhibition of cell division and hence renal repair, leading to acute renal failure (ARF) and death in mice. Renal injury initiated by low to moderate doses of DCVC is repaired by timely and adequate stimulation of renal cell division, tubular repair, restoration of renal structure and function leading to survival of mice. Recent studies have established that mice primed with a low dose of DCVC (15 mg/kg ip) 72 h before administration of a normally lethal dose (75 mg/kg ip) are protected from ARF and death (nephro-autoprotection). We showed that renal cell division and tissue repair stimulated by the low dose are sustained even after the lethal dose administration resulting in survival from ARF and death. If renal cell division induced by the low dose is indeed the critical mechanism of this autoprotection, then its ablation by the antimitotic agent colchicine (1.5 mg CLC/kg ip) should abolish autoprotection. The present interventional experiments were designed to test the hypothesis that DCVC autoprotection is due to stimulated cell division and tissue repair by the priming low dose. CLC intervention at 42 and 66 h after the priming dose resulted in marked progressive elevation of plasma blood urea nitrogen and creatinine resulting in ARF and death of mice. Light microscopic examination of hematoxylin and eosin-stained kidney sections revealed progression of renal necrosis concordant with progressively failing renal function. With CLC intervention, S-phase stimulation (as assessed by BrdU pulse labeling), G1-to-S phase clearance, and cell division were diminished essentially abolishing the promitogenic effect of the priming low dose of DCVC. Phospho-retinoblastoma protein (P-pRB), a crucial protein for S-phase stimulation, and other cellular signaling mechanisms regulating P-pRB were investigated. We report that decreased P-pRB via activation of protein phosphatase-1 by CLC is the critical mechanism of this inhibited S-phase stimulation and ablation of autoprotection with CLC intervention. These findings lend additional support to the notion that stimulated cell division and renal tissue repair by the priming dose of DCVC are the critical mechanisms that allow sustained compensatory tissue repair and survival of mice in nephro-autoprotection.

Influence of TH1/TH2 Switched Immune Response on Renal Ischemia-Reperfusion Injury

BACKGROUND/AIMS

Recent evidence shows a critical role of the CD4+ T cell with the Th1/Th2 paradigm as a possible effector mechanism in ischemia and reperfusion injury. We hypothesize that a polarized Th1 activation response may negatively influence the renal IRI through its relationship with chemokine production (MCP-1) and with a protective tissue response (HO-1).

METHODS

We subjected mice to renal ischemia for 45 min using IL-4 and IL-12 knockout C57BL/6. We then measured serum urea levels, performed histomorphometric analysis for tubular necrosis and regeneration, and evaluated the mRNA expression of HO-1, t-bet, Gata-3 and MCP-1 by real-time PCR at 24, 48 and 120 h after surgery.

RESULTS/CONCLUSIONS

The IL-4 knockout mice had a statistically significant rise in serum urea levels post IRI compared with control animals. The IL-12-deficient mice were not affected. The IL-4-deficient mice had a statistically significant increase in tubular injury and impairment in cell regeneration. The IRI in IL-4-deficient mice was accompanied by higher levels of HO-1, t-bet and later up-regulation of MCP-1. These findings suggest that the deleterious effects of the Th1 cell involve increased production of chemokines such as MCP-1.

Protection of HIF-1-deficient primary renal tubular epithelial cells from hypoxia-induced cell death is glucose dependent

Ischemic acute renal failure is a frequent clinical problem in hospitalized patients and is associated with significant mortality. Hypoxia-inducible factor 1 (HIF-1) mediates cellular adaptation to hypoxia by regulating biological processes important for cell survival, which include glycolysis, angiogenesis, erythropoiesis, apoptosis, and proliferation. To investigate the role of HIF-1 in hypoxia-induced renal epithelial cell death, we generated mice that allow inactivation of HIF-1α by tetracycline-inducible Cre-loxP-mediated recombination in primary renal proximal tubule cells (PRPTC), resulting in a suppression of HIF-1-mediated gene transcription during oxygen deprivation. In the absence of glucose, the onset and the degree of hypoxia-induced cell death in HIF-1-deficient PRPTC were comparable to wild-type cells. However, when glucose availability was limited, the onset of cell death was delayed in either PRPTC that were HIF-1 deficient or in wild-type PRPTC when glycolysis or glucose uptake was partially inhibited. Our findings suggest in an in vitro genetic model that 1) the generation of adequate energy levels for the maintenance of PRPTC viability under hypoxia does not require HIF-1 and 2) that HIF-1 regulates the timing of hypoxia-induced cell death and apoptosis onset through its effects on glucose consumption.

Comparison and interpretation of urinalysis performed by a nephrologist versus a hospital-based clinical laboratory

BACKGROUND

Urinalysis (UA) is considered the most important laboratory test in evaluating patients with kidney disease. Anecdotally, we have observed differences between results of UA performed by nephrologists compared with those performed by certified medical technologists or clinical laboratory scientists that could affect a clinician's diagnosis. Whether there are differences between UA performed by the clinical laboratory and that performed by a nephrologist was determined, and accuracy of diagnosis based on interpretation of the UA was compared.

METHODS

Urine samples were obtained from 26 patients with acute renal failure (ARF). An aliquot of urine was sent to the clinical laboratory for UA. Nephrologist A, blinded to the patient's clinical information, performed a UA on the other aliquot of urine, generated a report, and assigned the most likely diagnosis for ARF based on UA findings. Nephrologist B, also blinded to the clinical information, reviewed nephrologist A's UA reports and assigned a diagnosis for ARF to each report. Nephrologists A and B both assigned a diagnosis (or diagnoses) for the ARF based on laboratory UA results. These 4 sets of diagnoses were compared with those assigned by the consult nephrologists.

RESULTS

Nephrologist A correctly diagnosed the cause of ARF in 24 of 26 samples (92.3% success rate) based on his performance of the UA. Diagnoses by nephrologists A and B, based on their review of the clinical laboratory UA report, were correct in only 23.1% and 19.2% of the samples, respectively. Accuracy of diagnosis for nephrologist B improved to 69.3% when she reviewed UA reports from nephrologist A. Nephrologist A's review of urine sediment was significantly more accurate than interpretations by nephrologist A or B of clinical laboratory reports (sign test, P < 0.001). Nephrologist A reported a greater number of renal tubular epithelial (RTE) cells (P < 0.0001), granular casts (P = 0.0017), hyaline casts (P = 0.0233), RTE casts (P = 0.0008), and dysmorphic red blood cells. The laboratory noted a greater number of squamous cells (P = 0.0034).

CONCLUSION

A nephrologist is more likely to recognize the presence of RTE cells, granular casts, RTE casts, and dysmorphic red blood cells in urine. The laboratory may be reporting RTE cells incorrectly as squamous epithelial cells. Nephrologist-performed UA is superior to laboratory-performed UA in determining the correct diagnosis.

Molecular mechanisms of enhanced renal cell division in protection againstS-1,2-dichlorovinyl-l-cysteine-induced acute renal failure and death

Sustained activation of ERK 1/2 by a low dose (15 mg/kg ip) of S-1,2-dichlorovinyl-l-cysteine (DCVC) 72 h before administration of a lethal dose of DCVC (75 mg/kg ip) enhances renal cell division and protects mice against acute renal failure (ARF) and death (autoprotection). The objective of this study was to determine correlation among extent of S-phase DNA synthesis, activation of transcription factors, expression of G1/S cyclins, cyclin-dependent kinases (CDKs), and CDK inhibitors downstream of ERK 1/2 following DCVC-induced ARF in autoprotection. Administration of the lethal dose alone caused a general downregulation or an unsustainable increase, in transcriptional and posttranscriptional events thereby preventing G1-S transition of renal cell cycle. Phosphorylation of IκBα was inhibited resulting in limited nuclear translocation of NF-κB. However, cyclin D1 expression was high probably due to transcriptional cooperation of AP-1. Cyclin D1/cyclin-dependent kinase 4 (cdk4)-cdk6 system-mediated phosphorylation of retinoblastoma protein was downregulated due to overexpression of p16 at 24 h after exposure to the lethal dose alone. Inhibition of S-phase stimulation was confirmed by proliferating cell nuclear antigen assay (PCNA). This inhibitory response was prevented if the lethal dose was administered 72 h after the low priming dose of DCVC due to promitogenic effect of the low dose. NF-κB-DNA binding is not limited if mice were pretreated with the priming dose. Cyclin D1/cdk4-cdk6 expression stimulated by the priming dose of DCVC was unaltered even after the lethal dose in the autoprotected group, explaining higher phosphorylated-pRB and S-phase stimulation found in this group. These results were corroborated with PCNA immunohistochemistry. These findings suggest that the priming dose relieves the block on compensatory tissue repair by upregulation of promitogenic mechanisms, normally blocked by the high dose when administered without the prior priming dose.

Biocompatible hemodialysis membranes for acute renal failure

BACKGROUND

Acute renal failure (ARF) is associated with substantial morbidity and mortality. Some trials have reported a survival advantage among patients dialyzed with biocompatible membranes (BCM) compared to bioincompatible membranes (BICM). These findings were not consistently observed in subsequent studies.

OBJECTIVES

To ascertain whether the use of BCM confers an advantage in either survival or recovery of renal function over the use of BICM in adult patients with ARF requiring intermittent hemodialysis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library - Issue 1, 2004), MEDLINE (1966 to January 2004), EMBASE (1980 to January 2004), the Mexican Index of Latin American Biomedical Journals IMBIOMED (1990 to January 2004), the Latin American and Caribbean Health Sciences Literature Database LILACS (1982 to January 2004), and reference lists of articles.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing the use of a BCM with a BICM in patients > 18 years of age with ARF requiring intermittent hemodialysis.

DATA COLLECTION AND ANALYSIS

Two authors extracted the data independently. Cellulose-derived dialysis membranes were classified as BICM, and synthetic dialyzers were considered as BCM. The main outcomes were all-cause mortality and recovery of renal function by type of dialyzer. We further explored these outcomes according to the flux properties (high-flux or low-flux) of each of these dialyzers. A meta-analysis was conducted by combining data using a random-effects model.

MAIN RESULTS

Nine studies were included in the primary analysis of mortality, with a total of 1062 patients. None of the pooled RR's reached statistical significance. The pooled relative risk (RR) for mortality was 0.93 (95% confidence interval (CI) = 0.81 to 1.07). The overall RR for recovery of renal function, inclusive of 1038 patients from nine studies was 1.09 (95% CI 0.90 to 1.31). The pooled RR for mortality by dialyzer flux property was 1.03 (95% CI 0.82 to 1.30). The RR for recovery of renal function by flux property was 0.85 (95% CI 0.55 to 1.31). A meta-analysis of mortality of kidney transplant recipients was not possible, but the analysis of recovery of renal function in this patient population was 1.09 (95% CI 0.91to 1.31). Results of sensitivity analyses did not differ significantly from the primary analyses.

AUTHORS' CONCLUSIONS

There is no demonstrable clinical advantage to the use of BCM versus BICM in patients with ARF who require intermittent hemodialysis.

Polymorphism of host response genes: Implications in the pathogenesis and treatment of acute renal failure

Acute inflammatory disorders are the result of an interaction between genetic and environmental factors, and are often characterized by an imbalance between pro- and anti-inflammatory host immune responses. Over the past decade, polymorphisms of host response genes have been explored as genetic risk and prognostic markers in the course and severity of acute inflammatory disorders. Increasing evidence supports an important role for inflammatory mechanisms in the pathogenesis of acute renal failure (ARF) following both ischemic and nephrotoxic injury. The use of genetic epidemiology may become a useful tool to identify patients with an altered susceptibility to developing hospital-acquired ARF, and stratify those who may benefit from preventive therapies that modulate host immune responses in a favorable way. This review summarizes the existing experimental and clinical studies supporting the role of inflammation in ARF and critically appraises studies that have examined polymorphism of immune response genes as potential determinants of susceptibility to and severity of acute inflammatory disorders. Conclusions are drawn on the application of genetic epidemiology to the field of ARF and the rationale for further research on the role of genetic markers in ARF.

Renal protection strategies in the perioperative period

The development of acute renal failure (ARF) in the perioperative period continues to be a vexing condition associated with high morbidity and mortality rates which have been unchanged for several decades. In this article I briefly review recent research categorizing pathogenesis of ARF and mechanisms of recovery. Once ARF is established, its maintenance phase is dependent on several mechanisms that interact with cellular integrity. The main focus of the article is on assessing clinical and experimental interventions to prevent ARF. Unfortunately, existing pharmacological and other interventions show a rather limited efficacy in preventing ARF.

T cells as mediators in renal ischemia/reperfusion injury

Inflammation has been established to contribute substantially to the pathogenesis of ischemia/reperfusion (I/R) with a central role for particular cells, adhesion molecules, and cytokines. Until recently, most of the research trying to unravel the pathogenesis of I/R injury has been focused on the role of neutrophils. However, recent studies have brought evidence that T cells and macrophages are also important leukocyte mediators of renal and extrarenal (liver) I/R injury. In vivo depletion of CD4+ cells but not CD8+ cells in wild-type mice was protective in I/R of the kidney. A marked preservation of liver function was also found after I/R in T-cell deficient athymic mice. Blocking the b130/CD28 costimulatory pathway by CTLA-4 Ig (recombinant fusion protein) ameliorated renal dysfunction and decreased mononuclear cell infiltration in I/R of the kidney. b130-1 expression was found limited to the membrane of the endothelial cells of the ascending vasa recta, resulting in trapping of CD28-expressing CD4 T cells. This trapping of leukocytes results in the upstream congestion in the ascending arterial vasa recta, generating the since more than 150 years described medullary vascular congestion of the kidney soon after ischemic injury. It seems worthwhile to study a combination therapy using anti-inflammatory/anti-adhesion molecules in the early phase of I/R.

Clinical and laboratory diagnosis of acute renal failure

Acute renal failure (ARF) is defined in general terms as an abrupt decrease in renal function sufficient enough to result in retention of nitrogenous waste and disrupt fluid and electrolyte homeostasis. There is no consensus regarding a quantifiable definition of ARF. Prompt evaluation of ARF is vital because ARF can be the end result of diverse processes which can often be reversed or attenuated through therapy directed at the underlying condition. Evaluation begins with careful review of the patient's history, previous medical records, physical examination, urinalysis, and available laboratory data. Routine urine chemical indices, calculation of the fractional excretion of sodium, and examination of the urine sediment are valuable in characterizing the cause of ARF. When this evaluation fails to yield a diagnosis, further testing may be required to evaluate intravascular volume status or diagnose a systemic disorder or glomerular cause of ARF. Response to therapeutic trials may provide a diagnosis. When a diagnosis cannot be made with reasonable certainty through this evaluation renal biopsy should be considered.

Renal function after cardiac surgery: adverse effect of furosemide

Renal failure is a frequent event after cardiopulmonary by-pass. Hemodynamic alterations that occur during surgery, as well as factors depending on the host, are the main risk factors for renal dysfunction. To evaluate the frequency and risk factors for renal dysfunction in this setting, a cohort of fifty patients with preoperative serum creatinine under 1.5 mg/dL, submitted to cardiac surgery with cardiopulmonary by-pass was analyzed. Variables related to preoperative patient condition, intraoperative and postoperative periods were recorded. Renal function was assessed by clearances of creatinine, urea and free water, also by fractional excretion of sodium (FENa), at baseline, at anesthetic induction and during postoperative period. Patients were arbitrarily divided in two groups, according to the serum creatinine (S(Cr)) value at the end of the postoperative period: Group 1: S(Cr) < 2 mg/dL (n = 44 patients (88.5%)) and Group II: S(Cr) > 2 mg/dL (n = 6 patients (11.5%)). A decrease of renal function was observed in all patients: creatinemia raised from 1.04 +/- 0.2 to 1.55 +/- 0.4 mg/dL (33%), associated with a rise in FENa. Differences between group I and group II using univariate analysis were: baseline serum creatinine (1.01 +/- 0.23 mg/dL vs. 1.26 +/- 0.19 mg/dL, p = 0.03), FENa (0.99 +/- 0.8 vs. 2.2 +/- 2.1, p = 0.04), furosemide dose during surgery normalized to body surface area (93.2 +/- 23 mg/1.73 m2 BSA vs. 135 +/- 38 mg/1.73 m2 BSA, p < 0.001), and hemodilution index (17.3 +/- 4.3% vs. 22.8 +/- 3.2%, p < 0.01). In the multiple regression model, baseline creatinemia and furosemide dose were associated to renal dysfunction.

Gene expression in early ischemic renal injury: clues towards pathogenesis, biomarker discovery, and novel therapeutics

Acute renal failure (ARF) represents a common and serious problem in clinical medicine. Renal ischemia-reperfusion injury (IRI) is the major cause of ARF in the native and transplanted kidney. Several decades of research have provided successful therapeutic approaches in animal models, but translational efforts in humans have yielded disappointing results. The major reasons for this include a lack of early markers for ARF (and hence a delay in initiating therapy), and the multi-factorial nature of the disease. This review focuses on the use of cDNA microarrays to elucidate the molecular genetic mechanisms underlying tubule cell apoptosis, and to identify novel biomarkers for early renal IRI. Also presented is a comparative temporal analysis of cDNA microarray results from mature kidneys following IRI and during normal nephrogenesis. Molecular genetic evidence for the notion that regeneration recapitulates development in the kidney, and that injured tubule cells possess the capacity to de-differentiate to the earliest stages of development, is presented. The implications of these findings to the ability of the kidney to repair itself and potential strategies for accelerating recovery are briefly discussed.

Molecular mechanisms of recovery from acute renal failure

OBJECTIVES

Despite technological advances in renal replacement therapy over the past few years, acute renal failure in the intensive care unit remains associated with high morbidity and mortality rates. In this article I review recent research aimed at elucidating mechanisms of renal recovery from acute injury.

DESIGN

Review of the literature.

CONCLUSIONS

A number of peptide growth hormones are reviewed, including epidermal growth factor, insulin-like growth factor-1, thyroxine, hepatocyte growth factor, and bone morphogenetic protein-7 promote renal regeneration in model systems. Unfortunately, despite promising studies in animal models of toxin and ischemia-induced acute tubular necrosis, human studies have not shown any clinical benefit. However, several of these molecules have not been studied in clinical trials. Existing pharmacologic strategies have a limited role in renal recovery. Finally, several recent studies have focused on the effects of renal replacement therapy on renal recovery, but additional studies are needed to confirm and extend these results.

Integration of APACHE II and III scoring systems in extremely high risk patients with acute renal failure treated by dialysis

OBJECTIVE

Acute physiology, age, chronic health evaluation II and III (APACHE II and III) scoring systems obtained on the day of the initiation of dialysis were compared the mortality rate among in critically ill patients with acute renal failure requiring dialysis.

DESIGN

Retrospective study.

SETTING

Intensive care units in a tertiary care university hospital in Taiwan.

PATIENTS

100 patients diagnosed with acute renal failure and requiring dialysis were admitted to intensive care units from January 1997 through December 1998.

INTERVENTIONS

Information deemed necessary to compute the APACHE II and APACHE III score on the day of dialysis initiation was collected.

MEASUREMENTS AND RESULTS

The overall hospital mortality rate was 71%. The relationship between APACHE II and APACHE III scores for patients was linear and correlated significantly in all subgroups. Goodness-of-fit was good for APACHE II and APACHE III models. Both reported good areas under receiver operating characteristic curve. Death in most patients was related to a higher APACHE II or APACHE III score during the 24 h immediately preceding the initiation of acute hemodialysis. Our results indicated a significant rise in mortality rates associated with higher APACHE II or III scores among all patients. Although less than 60%, the mortality rates markedly increased extent when APACHE II score of 24 or higher or APACHE III score above 90 had mortality rates exceeding 85%.

CONCLUSION

Both predictive models demonstrated a similar degree of overall goodness-of-fit. Although APACHE II showed better calibration, APACHE III was better in terms of discrimination. The prediction accuracy of the APACHE II score for extremely high-risk patients is further enhanced by specific utility of APACHE III scoring as a second prediction model when the AII score is 24 or higher.

Acute renal failure

Acute renal failure is characterized by an 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. There are many different causes of acute renal failure in children, including prerenal disease, intrinsic renal failure, which includes ischemic hypoxic insults, and obstructive uropathy. This review will focus on hypoxic/ischemic acute renal failure, the most common causes of hospital acquired acute renal failure in children. This review will briefly discuss the epidemiology and incidence of acute renal failure in pediatric patients and review new insights into the pathogenesis of acute renal failure. including hemodynamic alterations induced by alterations in nitric oxide and endothelin metabolism, the role of the inflammatory response, and alteration in polarity in the acute renal failure. The therapy of acute renal failure has changed substantially during the past few years. Controlled trials (in adults) to test the efficacy of "renal dose" dopamine have shown that it is ineffective, and hemofiltration has become increasingly popular as a choice of therapy for acute renal failure.

Impact of intermittent hemodialysis variables on clinical outcomes in acute renal failure

When hospital-acquired acute renal failure (ARF) is severe enough to require renal replacement therapy, mortality rates are extremely high, exceeding 50%. The potential impact of renal replacement therapy on clinical outcomes in ARF remains a subject of ongoing investigation and controversy. This article reviews in depth all of the clinical trials that have examined the effect of dialysis-related variables on clinical outcomes in patients with ARF requiring intermittent hemodialysis. In particular, the role of biocompatibility of dialyzer membranes, and timing, intensity, and adequacy of dialysis are discussed.

Comparing continuous hemofiltration with hemodialysis in patients with severe acute renal failure

Continuous venovenous hemofiltration (CVVH) or CVVH with additional diffusive dialysis (CVVH-D) has theoretical advantages in treating severe acute renal failure (ARF), but no prospective clinical trials or restrospective comparison studies have clearly shown its superiority over intermittent hemodialysis (HD). To evaluate this question, all 349 adult patients with ARF receiving renal replacement therapy (RRT) at our medical center during 1995 and 1996 were analyzed using multivariate Cox proportional hazards methods. Initial univariate analysis showed the odds of death when receiving initial CVVH to be more than twice those when receiving initial HD (risk for death, 2.03; P < 0.01). Progressive exclusion of patients in whom the RRT modality might not be open to choice and the risk for death was very high (systolic blood pressure < 90 mm Hg; total bilirubin level > 15 mg/dL; or total RRT < 48 hours) for total RRT left 227 patients in whom the risk for death was 1.09 (95% confidence interval [CI], 0.67 to 1.80; P = 0.72) for initial CVVH, virtually equivalent to the risk for initial HD. Comorbid indicators significantly associated with death or failure to recover renal function included: older age; medical rather than surgical diagnosis; preexisting infection or trauma and liver disease as primary diagnoses; and abnormal bilirubin level or vital signs at initiation of RRT. These results show that the high crude mortality rate of patients undergoing CVVH was related to severity of illness and not the treatment choice itself. With the addition of more inclusive comorbidity data and a broader spectrum of interim outcomes, this type of analysis is a practical alternative to what would almost assuredly be a cumbersome and costly prospective, controlled trial comparing traditional HD with CVVH.