Epidemiology of acute renal failure: a prospective, multicenter, community-based study. Madrid Acute Renal Failure Study Group

Acute kidney injury after aortic valve replacement: incidence, risk factors and outcomes

The occurrence of acute kidney injury (AKI) following aortic valve replacement (AVR) has very serious clinical implications and has therefore been the focus of several studies. The authors report the results of previous studies evaluating both transcatheter AVR (TAVR) and indirectly surgical AVR (SAVR) through looking at cardiopulmonary bypass (CPB) cardiac surgeries, and identify the incidence, predictors and outcomes of AKI following AVR. In most studies, AKI was defined using the Risk, Injury, Failure, Loss and End Stage, Valve Academic Research Consortium (modified Risk, Injury, Failure, Loss and End Stage) or Valve Academic Research Consortium-2 (Acute Kidney Injury Network) AKI classification criteria. Twelve studies including more than 90,000 patients undergoing cardiac surgery on CPB were considered as well as 26 studies with more than 6000 patients undergoing TAVR. Depending on the definition used, AKI occurred in 3.4-43% of SAVR cases with up to 2.5% requiring dialysis, and in 3.4-57% of TAVR cases. Factors identified as independent predictors of AKI were: baseline kidney failure, EUROSCORE, diabetes mellitus, hypertension, chronic obstructive pulmonary disease, anemia, peripheral vascular disease, heart failure, surgical priority, CPB time, reoperation, use of intra-aortic balloon pump, need for re-exploration, contrast agent volume, transapical access, blood transfusion, postoperative thrombocytopenia, postoperative leukocytosis as well as demographic variables such as age and female gender. The 30-day mortality rate for patients with AKI following SAVR ranged from 5.5 to 46% and was 3- to 16-times higher than in those without AKI. Similarly, patients who developed AKI after TAVR had a mortality rate of 7.8-29%, which was two- to eight-times higher than those who did not suffer from AKI. AKI confers up to a fourfold increase in 1-year mortality. Finally, hospital length of stay was significantly increased in patients with AKI in both SAVR and TAVR groups, with increases up to 3- and 2.5-times, respectively.

The restrained expression of NF-kB in renal tissue ameliorates folic acid induced acute kidney injury in mice

The Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) represent family of structurally-related eukaryotic transcription factors which regulate diverse array of cellular processes including immunological responses, inflammation, apoptosis, growth & development. Increased expression of NF-kB has often been seen in many diverse diseases, suggesting the importance of genomic deregulation to disease pathophysiology. In the present study we focused on acute kidney injury (AKI), which remains one of the major risk factor showing a high rate of mortality and morbidity. The pathology associated with it, however, remains incompletely known though inflammation has been reported to be one of the major risk factor in the disease pathophysiology. The role of NF-kB thus seemed pertinent. In the present study we show that high dose of folic acid (FA) induced acute kidney injury (AKI) characterized by elevation in levels of blood urea nitrogen & serum creatinine together with extensive tubular necrosis, loss of brush border and marked reduction in mitochondria. One of the salient observations of this study was a coupled increase in the expression of renal, relA, NF-kB2, and p53 genes and proteins during folic acid induced AKI (FA AKI). Treatment of mice with NF-kB inhibitor, pyrrolidine dithio-carbamate ammonium (PDTC) lowered the expression of these transcription factors and ameliorated the aberrant renal function by decreasing serum creatinine levels. In conclusion, our results suggested that NF-kB plays a pivotal role in maintaining renal function that also involved regulating p53 levels during FA AKI.

Renal Safety Pharmacology in Drug Discovery and Development

The kidney is a complex excretory organ playing a crucial role in various physiological processes such as fluid and electrolyte balance, control of blood pressure, removal of waste products, and drug disposition. Drug-induced kidney injury (DIKI) remains a significant cause of candidate drug attrition during drug development. However, the incidence of renal toxicities in preclinical studies is low, and the mechanisms by which drugs induce kidney injury are still poorly understood. Although some in vitro investigational tools have been developed, the in vivo assessment of renal function remains the most widely used methodology to identify DIKI. Stand-alone safety pharmacology studies usually include assessment of glomerular and hemodynamic function, coupled with urine and plasma analyses. However, as renal function is not part of the ICH S7A core battery, such studies are not routinely conducted by pharmaceutical companies. The most common approach consists in integrating renal/urinary measurements in repeat-dose toxicity studies. In addition to the standard analyses and histopathological examination of kidneys, novel promising urinary biomarkers have emerged over the last decade, offering greater sensitivity and specificity than traditional renal parameters. Seven of these biomarkers have been qualified by regulatory agencies for use in rat toxicity studies.

Renal impairment in cirrhosis unrelated to hepatorenal syndrome

Renal impairment is common in liver disease and may occur as a consequence of the pathophysiological changes that underpin cirrhosis or secondary to a pre-existing unrelated insult. Nevertheless, the onset of renal impairment often portends a worsening prognosis. Hepatorenal syndrome remains one of the most recognized and reported causes of renal impairment in cirrhosis. However, other causes of renal impairment occur and can be classified into prerenal, intrinsic or postrenal, which are the subjects of the present review.

Targeted deletion of p53 in the proximal tubule prevents ischemic renal injury

The contribution of p53 to kidney dysfunction, inflammation, and tubular cell death, hallmark features of ischemic renal injury (IRI), remains undefined. Here, we studied the role of proximal tubule cell (PTC)-specific p53 activation on the short- and long-term consequences of renal ischemia/reperfusion injury in mice. After IRI, mice with PTC-specific deletion of p53 (p53 knockout [KO]) had diminished whole-kidney expression levels of p53 and its target genes, improved renal function, which was shown by decreased plasma levels of creatinine and BUN, and attenuated renal histologic damage, oxidative stress, and infiltration of neutrophils and macrophages compared with wild-type mice. Notably, necrotic cell death was attenuated in p53 KO ischemic kidneys as well as oxidant-injured p53-deficient primary PTCs and pifithrin-α-treated PTC lines. Reduced oxidative stress and diminished expression of PARP1 and Bax in p53 KO ischemic kidneys may account for the decreased necrosis. Apoptosis and expression of proapoptotic p53 targets, including Bid and Siva, were also significantly reduced, and cell cycle arrest at the G2/M phase was attenuated in p53 KO ischemic kidneys. Furthermore, IRI-induced activation of TGF-β and the long-term development of inflammation and interstitial fibrosis were significantly reduced in p53 KO mice. In conclusion, specific deletion of p53 in the PTC protects kidneys from functional and histologic deterioration after IRI by decreasing necrosis, apoptosis, and inflammation and modulates the long-term sequelae of IRI by preventing interstitial fibrogenesis.

Etiology and outcomes of anuria in acute kidney injury: a single center study

BACKGROUND

It was previously known that anuric acute kidney injury (AKI) is uncommon and its occurrence suggests complete ureteral obstruction, shock, or a major vascular event. As the epidemiology of AKI has significantly changed over the past decade, it is possible that the incidence, etiology, or clinical characteristics of anuric AKI have also changed.

METHODS

A prospective cohort study was conducted that included all patients undergoing renal replacement therapy (RRT) for AKI during a 2-year period in a tertiary hospital. Patients were classified as having anuric, oliguric, or nonoliguric AKI based on their volume of urine when RRT started using the modified Acute Kidney Injury Network criteria.

RESULTS

Of the 203 patients included in the study, 21.2% met the criteria for anuric AKI. Septic and postoperative AKI were the main causes of anuric AKI, with 60.5% of incidences occurring in hospital. Anuric AKI was associated with a younger age, a lower prevalence of pre-morbid chronic kidney disease and diabetes, more frequent continuous RRT requirement, and multi-organ dysfunction. In addition, patients with anuric AKI had a higher rate of in-hospital mortality and long-term dependence on RRT than patients with nonanuric AKI.

CONCLUSION

Anuric AKI is common, with sepsis as the main etiological insult, and is associated with adverse outcomes among patients with AKI who require RRT.

AKI complications in critically ill patients: association with mortality rates and RRT

BACKGROUND AND OBJECTIVES

AKI is associated with short- and long-term mortality. However, the exact contribution of AKI complications to the burden of mortality and whether RRT has any beneficial effect on reducing mortality rates in critically ill AKI patients are unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a retrospective analysis using data from the Multiparameter Intelligent Monitoring in Intensive Care II project. A total of 18,410 adult patients were enrolled from four intensive care units from a university hospital from 2001 to 2008.

RESULTS

Overall, 10,245 patients developed AKI. After adjustments, the odds ratios (ORs) for hospital mortality were 1.73 (95% confidence interval [95% CI], 1.52 to 1.98) for AKI stage 1, 1.88 (95% CI, 1.57 to 2.25) for stage 2, and 2.89 (95% CI, 2.41 to 3.46) for stage 3. Totals of 33%, 59%, and 70% of the excess mortality rates associated with AKI stages 1, 2, and 3, respectively, were attenuated by the inclusion of each AKI-related complication in the model. The main burden of excess hospital mortality associated with AKI was attenuated by metabolic acidosis and cumulative fluid balance. Long-term mortality was not attenuated by any of the associated complications. Next, we used two different approaches to explore the associations between RRT, AKI complications, and hospital mortality: multivariate analysis and propensity score matching. In both approaches, the sensitivity analysis for RRT was associated with a better hospital survival in only the following AKI-related subgroups: hyperkalemia (OR, 0.55; 95% CI, 0.35 to 0.85), metabolic acidosis (OR, 0.70; 95% CI, 0.53 to 0.92), cumulative fluid balance >5% of body weight (OR, 0.60; 95% CI, 0.40 to 0.88), and azotemia (OR, 0.57; 95% CI, 0.40 to 0.81).

CONCLUSIONS

A majority of the excess risk of mortality associated with AKI was attenuated by its fluid volume and metabolic complications, particularly in severe AKI. In addition, this study demonstrated that RRT is associated with a better outcome in patients with AKI-related complications.

ACR Appropriateness Criteria(®) on renal failure

Imaging plays a role in the management of patients with acute kidney injury or chronic kidney disease. However, clinical circumstances strongly impact the appropriateness of imaging use. In patients with newly detected renal dysfunction, ultrasonography can assess for reversible causes, assess renal size and echogenicity, and thus, establish the chronicity of disease. Urinary obstruction can be detected, but imaging is most useful in high-risk groups or in patients in whom there is a strong clinical suspicion for obstruction. Computed tomography, computed tomography or magnetic resonance arteriography, and percutaneous ultrasound-guided renal biopsy are valuable in other clinical situations. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Hsp72 is a novel biomarker to predict acute kidney injury in critically ill patients

BACKGROUND AND OBJECTIVES

Acute kidney injury (AKI) complicates the course of disease in critically ill patients. Efforts to change its clinical course have failed because of the fail in the early detection. This study was designed to assess whether heat shock protein (Hsp72) is an early and sensitive biomarker of acute kidney injury (AKI) compared with kidney injury molecule (Kim-1), neutrophil gelatinase-associated lipocalin (NGAL), and interleukin-18 (IL-18) biomarkers.

METHODS

A total of 56 critically ill patients fulfilled the inclusion criteria. From these patients, 17 developed AKI and 20 were selected as controls. In AKI patients, Kim-1, IL-18, NGAL, and Hsp72 were measured from 3 days before and until 2 days after the AKI diagnosis and in no-AKI patients at 1, 5 and 10 days after admission. Biomarker sensitivity and specificity were determined. To validate the results obtained with ROC curves for Hsp72, a new set of critically ill patients was included, 10 with AKI and 12 with no-AKI patients.

RESULTS

Urinary Hsp72 levels rose since 3 days before the AKI diagnosis in critically ill patients; this early increase was not seen with any other tested biomarkers. Kim-1, IL-18, NGAL, and Hsp72 significantly increased from 2 days before AKI and remained elevated during the AKI diagnosis. The best sensitivity/specificity was observed in Kim-1 and Hsp72: 83/95% and 100/90%, respectively, whereas 1 day before the AKI diagnosis, the values were 100/100% and 100/90%, respectively. The sensibility, specificity and accuracy in the validation test for Hsp72 were 100%, 83.3% and 90.9%, respectively.

CONCLUSIONS

The biomarker Hsp72 is enough sensitive and specific to predict AKI in critically ill patients up to 3 days before the diagnosis.

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.

Bidirectional relationships between acute kidney injury and chronic kidney disease

PURPOSE OF REVIEW

Chronic kidney disease (CKD) remains one of the most potent predictors of acute kidney injury (AKI); however, recent epidemiologic studies have demonstrated a complex interplay between these two clinical entities. A growing body of evidence supports a bidirectional relationship: AKI leads to CKD, and the presence of CKD increases the risk of AKI. Additionally, several studies suggest that the presence of underlying CKD does modify the relation between AKI and adverse outcomes. In this article, we will review recent studies supporting the hypothesis that AKI leads to CKD and will explore the role of CKD as an effect modifier for AKI.

RECENT FINDINGS

A recent meta-analysis confirms the association between AKI and the development of CKD and end-stage renal disease. Patient survival and renal outcomes after AKI are influenced by the presence of underlying CKD. AKI survivors with complete recovery of renal function remain at elevated risk of developing de-novo CKD, which may influence long-term survival; however, recovery of kidney function after AKI is associated with better long-term survival and renal function.

SUMMARY

Recent findings support a strong association between AKI and CKD. There is uncertainty as to whether this relationship is causal. CKD is an effect modifier in AKI.

The growth of acute kidney injury: a rising tide or just closer attention to detail?

Acute kidney injury (AKI), previously termed acute renal failure, is associated with increased mortality, prolonged hospital stay, and accelerated chronic kidney disease (CKD). Over the past 2 decades, dramatic rises in the incidences of AKI have been reported, particularly within the United States. The question arises as to whether these changes reflect actual increases in disease incidence, or are potentially explained by the introduction of consensus definitions that rely on small standardized changes in serum creatinine, changes in coding and reimbursement, or increasingly available and more liberal use of dialysis. In this review, we explore the secular trends in AKI incidence in North America and Western Europe and its potential contributors.

Sodium phosphate does not increase risk for acute kidney injury after routine colonoscopy, compared with polyethylene glycol

BACKGROUND & AIMS

Oral sodium phosphate (OSP) is a common bowel purgative administered before colonoscopy; the Food and Drug Administration has warned against its use because of concerns about acute kidney injury (AKI) from the absorbed phosphate and dystrophic calcification. However, it is not clear if OSP is associated with AKI in the general population or in high-risk subgroups undergoing colonoscopy. We estimated the risk of AKI among patients undergoing a screening colonoscopy using OSP vs polyethylene glycol (PEG) for bowel cleansing in a large, US-based claims database.

METHODS

We used an insurance database to identify a cohort of patients ages 50 to 75 years who underwent screening colonoscopies as outpatients from January 2000 through November 2008 (before the Food and Drug Administration warning), receiving OSP (n = 121,266) or PEG (n = 429,430) within 30 days beforehand, without prior use of either drug. We collected data from patients for 6 months afterward to identify those who developed AKI or renal failure, or received dialysis. Adjusted and propensity score-matched hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models. We investigated the effects in subgroups with higher AKI risk (patients with chronic kidney disease, kidney stones, hypertension, or diabetes, or using antihypertensive or nonsteroidal anti-inflammatory drugs).

RESULTS

AKI occurred in 0.2% of OSP users and in 0.3% of PEG users (adjusted HR, 0.86; 95% CI, 0.75-0.99). OSP users matched well with PEG users, producing similar estimates (HR, 0.85; 95% CI, 0.72-1.01). We did not observe a consistent increase in the risk of AKI or other outcomes in any subgroups analyzed.

CONCLUSIONS

In a large database analysis, we did not associate administration of OSP before colonoscopy with increased risk of postprocedure AKI, even in high-risk clinical subgroups.

Acute and chronic kidney injury in nephrolithiasis

PURPOSE OF REVIEW

Nephrolithiasis is a common systemic disease associated with both acute kidney injury (AKI) and chronic kidney disease (CKD). The purpose of this review is to discuss recent publications regarding nephrolithiasis-associated kidney damage, with an emphasis on AKI.

RECENT FINDINGS

Nephrolithiasis is not a common cause of adult AKI (1-2% of cases), although it may be a more important factor in young children (up to 30%). The primary mechanism of nephrolithiasis-associated AKI is obstructive nephropathy, and factors on presentation with obstructive uropathy predict the likelihood of long-term renal recovery. Crystalline nephropathy is another potential pathway in certain circumstances that is often associated with a worse outcome. Recent studies have elucidated additional pathways whereby calcium oxalate crystals can cause acute injury, implicating innate immunity and intracellular inflammasome pathways. Several large cohort studies have demonstrated an independent association of nephrolithiasis with CKD and end-stage renal disease, although the effect size is modest. Urologic comorbidities, urinary infection, and shared underlying risk factors (e.g., diabetes, hypertension) all impact nephrolithiasis-associated CKD risk.

SUMMARY

Obstructive nephropathy and crystalline nephropathy both contribute to nephrolithiasis-associated AKI, although the latter appears to have a worse prognosis. Nephrolithiasis is an independent, albeit small, risk factor for CKD. Further study is needed to clarify the incidence and mechanisms of nephrolithiasis-associated AKI, and the relationship between nephrolithiasis-associated AKI and CKD.

Six-year single-center survey on AKI requiring renal replacement therapy: epidemiology and health care organization aspects

Evidence regarding hospital-based acute kidney injury (AKI) reveals a continuous increase in incidence over the years, at least in intensive care units (ICU). Fewer reports are available for non critically-ill patients admitted to general or specialist wards other than ICU (non-ICU). The consequence of greater incidence is an increase in therapies such as dialysis; but how the health care organization deals with this problem is not clearly known. Here we quantified the incidence of dialysis-requiring AKI (AKI-D) among patients admitted to a University Hospital which serves a population of 354,000 inhabitants. Between 2007 and 2012, the incidence of AKI-D increased from 209 to 410 per million population (pmp)/year; age of patients and cardiovascular comorbid pathologies also increased. AKI-D was more frequent in non-ICU and 32% of patients were admitted to ICU. Considering the site of treatment of non-ICU patients, in 2007 the ratio of patients admitted to non-ICU wards apart from Nephrology to those admitted to Nephrology was 1:1, but in 2012 the ratio increased to 2.4:1 (p < 0.05). The complexity of acute disease, measured with the New Simplified Acute Physiology Score (SAPS II), did not reveal differences over the years. The number of dialysis treatments/year increased by 82%, and the total hours/year increased by 86%. Low-efficiency daily dialysis was performed in 52.4% of patients admitted to ICU, but dialysis sessions longer than 8 h were performed in only 40% of cases. Overall, 6-year mortality was 48.8%, without significant differences over the years. Mortality in ICU was 65.6%, and in non-ICU 41.2% (p < 0.001). Dialysis treatments needed to be continued after hospital discharge in 21% of patients. We conclude that dialysis-requiring AKI is becoming more common, and that two-thirds of patients are admitted as non-ICU: in these patients, during the last year of the study, the treatment site was more frequently in non-ICUs other than Nephrology. Over the 6-year period, the local healthcare organization had to dispense 80% more dialysis treatments/year in terms of total number and hours of treatment. One-fifth of surviving patients needed to continue dialysis after hospital discharge. Our data highlight the public health importance of AKI and the need for adequate resources for Nephrology.

Pulse wave velocity and neutrophil gelatinase-associated lipocalin as predictors of acute kidney injury following aortic valve replacement

BACKGROUND

Accurate prediction, early detection and treatment of acute kidney injury (AKI) are essential for improving post-operative outcomes. This study aimed to examine the role of aortic stiffness and neutrophil gelatinase-associated lipocalin (NGAL) as predictors of AKI or need for early medical renal intervention following aortic valve replacement (AVR).

METHODS

Aortic pulse wave velocity and plasma NGAL were measured pre-operatively in recruited patients undergoing AVR for aortic stenosis (AS). Plasma NGAL was also measured at 3 and 18-24 hours after cardiopulmonary bypass (CPB). AKI was defined using RIFLE criteria. Early medical renal intervention included diuretics or dopamine infusion exclusively for renal causes.

RESULTS

Fifty-three patients aged 71 ± 9 years were included. Sixteen (30%) developed AKI (AKI-Yes) and 24 patients (45%) received early medical intervention (Intervention-Yes). There was no significant difference in the demographic, clinical or operative characteristics between the two groups for either outcome. PWV did not significantly correlate with AKI (r = 0.12, P = 0.13) or early intervention (r = 0.18, P = 0.18). At 3 h post-CPB, plasma NGAL was a much stronger predictor of both AKI and the need for early medical intervention than conventional markers such as creatinine (AKI: AUC 83%, 95% CI 0.70-0.95 vs. AUC 65%, 95% CI 0.47- 0.82; Medical intervention: AUC 84%, 95% CI 0.72-0.96 vs. AUC 56%, 95% CI 0.38-0.73). Post-CPB (3 hr) plasma NGAL was also significantly associated with AKI (r = 0.68, P < 0.001) at levels above 150 ng/ml; and significantly associated with early intervention (r = 0.64, P < 0.001) above 136 ng/ml. Simple linear regression showed no relationship between PWV and NGAL levels.

CONCLUSION

Aortic PWV does not correlate significantly with post-operative AKI or plasma NGAL levels in surgical AS patients. Post-operative NGAL is however an early and powerful predictive biomarker of both post-operative AKI and the need for early medical renal intervention and should consequently be considered in prediction models for AKI after cardiac surgery.

Acute kidney injury in a tropical country: a cohort study of 253 patients in an infectious diseases intensive care unit

INTRODUCTION

Acute kidney injury (AKI) is a frequent and potentially fatal complication in infectious diseases. The aim of this study was to investigate the clinical aspects of AKI associated with infectious diseases and the factors associated with mortality.

METHODS

This retrospective study was conducted in patients with AKI who were admitted to the intensive care unit (ICU) of a tertiary infectious diseases hospital from January 2003 to January 2012. The major underlying diseases and clinical and laboratory findings were evaluated.

RESULTS

A total of 253 cases were included. The mean age was 46±16 years, and 72% of the patients were male. The main diseases were human immunodeficiency virus (HIV) infection, HIV/acquired immunodeficiency syndrome (AIDS) (30%), tuberculosis (12%), leptospirosis (11%) and dengue (4%). Dialysis was performed in 70 cases (27.6%). The patients were classified as risk (4.4%), injury (63.6%) or failure (32%). The time between AKI diagnosis and dialysis was 3.6±4.7 days. Oliguria was observed in 112 cases (45.7%). The Acute Physiology and Chronic Health Evaluation (APACHE) II scores were higher in patients with HIV/AIDS (57±20, p-value=0.01) and dengue (68±11, p-value=0.01). Death occurred in 159 cases (62.8%). Mortality was higher in patients with HIV/AIDS (76.6%, p-value=0.02). A multivariate analysis identified the following independent risk factors for death: oliguria, metabolic acidosis, sepsis, hypovolemia, the need for vasoactive drugs, the need for mechanical ventilation and the APACHE II score.

CONCLUSIONS

AKI is a common complication in infectious diseases, with high mortality. Mortality was higher in patients with HIV/AIDS, most likely due to the severity of immunosuppression and opportunistic diseases.

Glomerular changes and alterations of zonula occludens-1 in the kidneys of Plasmodium falciparum malaria patients

Background

The process of cytoadhesion in Plasmodium falciparum malaria infection causes signaling processes that lead to structural and functional changes at the cellular level. Histopathological changes of acute kidney injury (AKI) in P. falciparum malaria often involve glomerular proliferation, thickening of the glomerular basement membrane, acute tubular necrosis, and interstitial inflammation. Focusing on the glomeruli, this study aimed to investigate glomerular and tight junction-associated protein- zonula occludens-1 (ZO-1) changes in P. falciparum malaria patients.

Methods

Kidney tissues were grouped into P. falciparum with AKI (Cr ≥ 265 μmol/L or 3 mg/dl), P. falciparum without AKI (Cr < 265 μmol/L), and normal kidney tissues (control group). Glomerular cells and the glomerular area were quantified and compared in three experimental groups. The tight junction was investigated immunohistochemically using tight junction-associated protein, ZO-1, protein marker. A further immunofluorescence study was performed in an endothelial cell (EC)-parasitized red blood cell (PRBC) co-culture system, to evaluate the tight junction protein.

Results

Glomerular cell proliferation was significant in P. falciparum with AKI (Cr ≥ 265 μmol/L). By contrast, the glomerular area decreased significantly. ZO-1 expression was significantly decreased in the AKI group compared with normal kidneys, and in kidney tissues without AKI (p < 0.05). This was further confirmed by the depletion in ZO-1 localization in ECs co-cultured with PRBCs.

Conclusions

In P. falciparum malaria with AKI, the decrease in glomerular area, despite glomerular cell proliferation, could be due to the collapse of cellular structures secondary to damaged tight junction-associated protein, ZO-1.

Thromboembolism as a cause of renal artery occlusion and acute kidney injury: the recovery of kidney function after two weeks

Thromboembolic occlusion is a rare cause of acute kidney injury (AKI). It may lead to permanent loss of renal function. Our patient, who had dilated cardiomyopathy and prosthetic aortic valve, presented with AKI due to thromboembolic arterial occlusion of a solitary functioning kidney. After 2 weeks delay, local intra-arterial thrombolytic treatment with recombinant tissue plasminogen activator was performed without sufficient effect. However, a subsequent percutaneous transluminal angioplasty with stenting was successful. Diuresis began immediately, and renal function was fully recovered after 2 weeks. Although there had been no evident arterial circulation in the kidney, we think that minor flow through subtotal occlusion of the main renal artery made the hibernation of kidney tissue possible and contributed to the recovery. Thus, even after prolonged ischemia, revascularization can be useful.

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).

Epidemiology and outcomes in community-acquired versus hospital-acquired AKI

BACKGROUND AND OBJECTIVE

Compared with AKI in hospitalized patients, little is known about patients sustaining AKI in the community and how this differs from AKI in hospital. This study compared epidemiology, risk factors, and short- and long-term outcomes for patients with community-acquired (CA) and hospital-acquired (HA) AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 15,976 patients admitted to two district general hospitals between July 11, 2011, and January 15, 2012 were studied. Through use of an electronic database and the AKI Network classification, 686 patients with CA-AKI and 334 patients with HA-AKI were identified. Patients were followed up for 14 months, and data were collated on short-term and long-term renal and patient outcomes.

RESULTS

The incidence of CA-AKI among all hospital admissions was 4.3% compared with an incidence of 2.1% of HA-AKI, giving an overall AKI incidence of 6.4%. Patients with CA-AKI were younger than patients with HA-AKI. Risks for developing HA and CA-AKI were similar and included preexisting CKD, cardiac failure, ischemic heart disease, hypertension, diabetes, dementia, and cancer. Patients with CA-AKI were more likely to have stage 3 AKI and had shorter lengths of hospital stay than patients with HA-AKI. Those with CA-AKI had better (multivariate-adjusted) survival than patients with HA-AKI (hazard ratio, 1.8 [95% CI, 1.44-2.13; P<0.001] for HA-AKI group). Mortality for the CA-AKI group was 45%; 43.7% of these deaths were acute in-hospital deaths. Mortality for the HA-AKI group was 62.9%, with 68.1% of these deaths being acute in-hospital deaths. Renal referral rates were low across the cohorts (8.3%). Renal outcomes were similar in both CA-AKI and HA-AKI groups, with 39.4% and 33.6% of patients in both groups developing de novo CKD or progression of preexisting CKD within 14 months, respectively.

CONCLUSION

Patients with CA-AKI sustain more severe AKI than patients with HA-AKI. Despite having risk factors similar to those of patients with HA-AKI, patients with CA AKI have better short- and long-term outcomes.

Renal neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 expression in children with acute kidney injury and Henoch-Schönlein purpura nephritis

The aim of this study was to investigate the expression of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in the serum, urine and renal tissues of children with acute kidney injury (AKI) and Henoch-Schönlein purpura nephritis (A-on-C). A prospective single-center evaluation of the serum, urine and renal NGAL and KIM-1 levels was performed in a cohort of children. Blood and 5-ml urine samples were collected from each patient for the analysis of NGAL and KIM-1 levels using an ELISA. In addition, the expression of NGAL and KIM-1 in the kidney was examined using immunohistochemistry in patients with A-on-C and HSPN. The expression of serum cystatin C, β2-macroglobulin and serum creatinine (SCr), as well as urinary β2-MG and SCr, in the patients with A-on-C was significantly higher than that of HSPN patients, and the expression of NGAL and KIM-1 in the serum and urine in the A-on-C patients was also significantly higher than that of HSPN patients. However, there were no significant differences in the urine protein levels between the two groups. NGAL and KIM-1 were expressed in renal tubular epithelial cells, and the expression of NGAL and KIM-1 in the A-on-C patients was significantly higher than that in HSPN patients. In addition, the urine NGAL and KIM-1 levels were negatively correlated with glomerular filtration rate, but there was no significant correlation between the urine NGAL/KIM-1 and urine protein levels. The changes in serum and urine NGAL and KIM-1 levels may be applied to the diagnosis of A-on-C.

[Acute kidney injury in elderly patient: Diagnostic and therapeutic aspects]

Acute renal failure in elderly patient is a public health problem. It is worsen by physiological status and anatomical changes associated with age, polymedication and chronic diseases. The etiologies of acute renal failure in the elderly are the same as in adults. Their distribution is specific with a large proportion of obstructive acute renal failure. The diagnostic and therapeutic strategies are the same as for young adults; the injection of iodinated-contrast should be avoided. Therapeutic strategies are discussed in terms of quality of life pre-morbid. Age is not considered a determinant of intensive treatment decisions. Renal replacement therapy in the elderly is not associated with excess mortality. Prevention of acute renal failure should be a permanent concern.

New tides: using zebrafish to study renal regeneration

Over the past several decades, the zebrafish has become one of the major vertebrate model organisms used in biomedical research. In this arena, the zebrafish has emerged as an applicable system for the study of kidney diseases and renal regeneration. The relevance of the zebrafish model for nephrology research has been increasingly appreciated as the understanding of zebrafish kidney structure, ontogeny, and the response to damage has steadily expanded. Recent studies have documented the amazing regenerative characteristics of the zebrafish kidney, which include the ability to replace epithelial populations after acute injury and to grow new renal functional units, termed nephrons. Here we discuss how nephron composition is conserved between zebrafish and mammals, and highlight how recent findings from zebrafish studies utilizing transgenic technologies and chemical genetics can complement traditional murine approaches in the effort to dissect how the kidney responds to acute damage and identify therapeutics that enhance human renal regeneration.

Severe infection, sepsis and acute kidney injury

Both severe infection and acute kidney injury (AKI) have a high, and rising incidence in critically ill patients admitted to the intensive care unit (ICU), and are associated with increased in-hospital mortality. Septic AKI patients are more severely ill compared to non-septic AKI patients and have worse outcome. Severe infection is a major cause of AKI in ICU patients, while conversely, AKI patients are at increased risk for infection. The dogma from the past relates the development of AKI in sepsis patients to decreased renal blood flow. However, current data suggest that there is no impairment of renal blood flow in patients with sepsis. The pathogenesis of AKI in sepsis is probably related to cytotoxic effects of inflammation, and impaired microcirculation. In addition, hyperglycaemia, and antimicrobial agent-induced drug nephrotoxicity may contribute to the development of AKI. On the other hand, AKI patients are at greater risk for infection as a result of volume overload, dialysis catheter insertion and secondary manipulation, inflammation of the kidneys leading to'organ cross talk', and impaired host immunity.

Severity of acute kidney injury and two-year outcomes in critically ill patients

BACKGROUND

The association between levels of acute kidney injury (AKI) during ICU admission and long-term mortality are not well defined.

METHODS

We examined medical records of adult patients admitted to a large tertiary medical center with no history of end-stage renal disease who survived 60 days from ICU admission between 2001 and 2007. Demographic, clinical, physiologic, and date of death data were extracted.

RESULTS

Among 15,048 patients, 12,399 (82.4%) survived 60 days from ICU admission and comprised the study population. AKI did not develop in 5,663 (45.7%) during ICU admission, whereas progressively severe levels of AKI as defined by Acute Kidney Injury Network (AKIN) criteria AKIN 1, AKIN 2, and AKIN 3 developed in 4,589 (37.0%), 1,613 (13.0%), and 534 (4.3%), respectively. Only 42.5% of patients with AKIN 3 survived 2 years from ICU admission. Patients with AKIN 3 had a 61% higher mortality risk 2 years from ICU discharge compared with patients in whom AKI did not develop. Patients with AKIN 1 and AKIN 2 had similar increased mortality risk 2 years from ICU admission (hazard ratio, 1.26 and 1.28, respectively). The level of estimated glomerular filtration rate on ICU discharge and chronic kidney disease were associated with long-term mortality.

CONCLUSIONS

Patients in whom AKI develops during ICU admission have significantly increased risks of death that extend beyond their high ICU mortality rates. These increased risks of death continue for at least 2 years after the index ICU admission.

Renal relevant radiology: use of ultrasonography in patients with AKI

As judged by the American College of Radiology Appropriateness Criteria, renal Doppler ultrasonography is the most appropriate imaging test in the evaluation of AKI and has the highest level of recommendation. Unfortunately, nephrologists are rarely specifically trained in ultrasonography technique and interpretation, and important clinical information obtained from renal ultrasonography may not be appreciated. In this review, the strengths and limitations of grayscale ultrasonography in the evaluation of patients with AKI will be discussed with attention to its use for (1) assessment of intrinsic causes of AKI, (2) distinguishing acute from chronic kidney diseases, and (3) detection of obstruction. The use of Doppler imaging and the resistive index in patients with AKI will be reviewed with attention to its use for (1) predicting the development of AKI, (2) predicting the prognosis of AKI, and (3) distinguishing prerenal azotemia from intrinsic AKI. Finally, pediatric considerations in the use of ultrasonography in AKI will be reviewed.

Acute kidney injury in statin initiators

PURPOSE

Statins are widely used for preventing cardiovascular disease, yet recent reports suggest an increased risk of acute kidney injury (AKI). We estimated the one-year risk of AKI associated with statin initiation and determined the comparative safety of individual statin formulations.

METHODS

We performed a cohort study in insurance billing data from commercial and Medicare insurance plans in the United States for the years 2000-2010. We identified statin initiators and non-users with histories of medication use and healthcare utilization. AKI diagnosis codes were identified in the one year following the index date. We estimated hazard ratios (HR) and 95% confidence intervals (CI) with adjusted and propensity score (PS)-matched Cox-proportional hazards models. Models were run separately in insurance groups and adjusted for cardiovascular and renal risk factors, markers of healthcare utilization, and other medication use.

RESULTS

We identified 3,905,155 statin initiators and 2,817,621 eligible non-users. The adjusted HR of AKI in statin initiators compared to non-users was: commercial, HR = 1.04 (95% CI: 0.99, 1.09); Medicare, HR = 0.72 (95% CI: 0.70, 0.75). PS-matching yielded: commercial, HR = 0.82 (95% CI: 0.78, 0.87); Medicare, HR = 0.66 (95% CI: 0.63, 0.69). As individual formulations, higher-potency simvastatin was associated with an increased risk of AKI over lower-potency simvastatin in adjusted models: commercial, HR = 1.42 (95% CI: 1.28, 1.58); Medicare, HR = 1.24 (95% CI: 1.15, 1.35).

CONCLUSIONS

As a class, statin initiation was not associated with an increase in AKI. However, higher-potency simvastatin did exhibit an increased AKI risk.

Raising awareness of acute kidney injury: a global perspective of a silent killer

Worldwide, acute kidney injury (AKI) is associated with poor patient outcomes. Over the last few years, collaborative efforts, enabled by a common definition of AKI, have provided a description of the epidemiology, natural history, and outcomes of this disease and improved our understanding of the pathophysiology. There is increased recognition that AKI is encountered in multiple settings and in all age groups, and that its course and outcomes are influenced by the severity and duration of the event. The effect of AKI on an individual patient and the resulting societal burden that ensues from the long-term effects of the disease, including development of chronic kidney disease (CKD) and end-stage renal disease (ESRD), is attracting increasing scrutiny. There is evidence of marked variation in the management of AKI, which is, to a large extent, due to a lack of awareness and an absence of standards for prevention, early recognition, and intervention. These emerging data point to an urgent need for a global effort to highlight that AKI is preventable, its course is modifiable, and its treatment can improve outcomes. In this article, we provide a framework of reference and propose specific strategies to raise awareness of AKI globally, with the goal to ultimately improve outcomes from this devastating disease.

Acute kidney injury: an increasing global concern

Despite an increasing incidence of acute kidney injury in both high-income and low-income countries and growing insight into the causes and mechanisms of disease, few preventive and therapeutic options exist. Even small acute changes in kidney function can result in short-term and long-term complications, including chronic kidney disease, end-stage renal disease, and death. Presence of more than one comorbidity results in high severity of illness scores in all medical settings. Development or progression of chronic kidney disease after one or more episode of acute kidney injury could have striking socioeconomic and public health outcomes for all countries. Concerted international action encompassing many medical disciplines is needed to aid early recognition and management of acute kidney injury.

Piecewise analysis of patient survival after onset of AKI

BACKGROUND AND OBJECTIVES

AKI affects approximately 2%-7% of hospitalized patients and >35% of critically ill patients. Survival after AKI may be described as having an acute phase (including an initial hyperacute component) followed by a convalescent phase, which may itself have early and late components.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the Veterans Affairs/National Institutes of Health Acute Renal Failure Trial Network (ATN) study was used to model mortality risk among patients with dialysis-requiring AKI. This study assumed that the mortality hazard can be described by a piecewise log-linear function with change points. Using an average likelihood method, the authors tested for the number of change points in a piecewise log-linear hazard model. The maximum likelihood approach to locate the change point(s) was then adopted, and associated parameters and standard errors were estimated.

RESULTS

There were 1124 ATN participants with follow-up to 1 year. The mortality hazard of AKI decreased over time with inflections in the rate of decrease at days 4, 42, and 148, with the sharpest change at day 42. The daily rate of decline in the log of the hazard for death was 0.220 over the first 4 days, 0.046 between day 4 and day 42, 0.017 between day 42 and day 148, and 0.003 between day 148 and day 365.

CONCLUSIONS

There appear to be two major phases of mortality risk after AKI: an early phase extending over the first 6 weeks and a late phase from 6 weeks to 1 year. Within the first 42 days, this can be further divided into hyperacute (days 1-4) and acute (days 4-42) phases. After 42 days, there appear to be early (days 42-148) and late (after day 148) convalescent phases. These findings may help to inform the design of AKI clinical trials and assist critical care physicians in prognostic stratification.

Long-term outcome of cats and dogs with acute kidney injury treated with intermittent hemodialysis: 135 cases (1997-2010)

OBJECTIVE

To determine the long-term outcome for small animal patients with acute kidney injury (AKI) treated with intermittent hemodialysis (IHD).

DESIGN

Retrospective case series.

ANIMALS

42 cats and 93 dogs treated with IHD for AKI.

PROCEDURES

Medical records of cats and dogs treated with IHD for AKI from January 1997 to October 2010 were reviewed. Standard methods of survival analysis with Kaplan-Meier product limit curves were used. The log-rank, Mann-Whitney, and Kruskal-Wallis tests were used to determine whether outcome, number of IHD treatments, or duration of hospitalization was different when dogs and cats were classified according to specific variables.

RESULTS

The overall survival rate at the time of hospital discharge was 50% (21/42) for cats and 53% (49/93) for dogs. The overall survival rate 30 days after hospital discharge was 48% (20/42) for cats and 42% (39/93) for dogs. The overall survival rate 365 days after hospital discharge was 38% (16/42) for cats and 33% (31/93) for dogs. For all-cause mortality, the median survival time was 7 days (95% confidence interval, 0 to 835 days) for cats and 9 days (95% confidence interval, 0 to 55 days) for dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Cats and dogs with AKI treated with IHD have survival rates similar to those of human patients. Although there was a high mortality rate prior to hospital discharge, those patients that survived to discharge had a high probability of long-term survival.

C-reactive protein exacerbates renal ischemia-reperfusion injury

Renal ischemia-reperfusion injury (IRI) is a common cause of acute kidney injury (AKI), occurring with hypotension and cardiovascular surgery and inevitably during kidney transplantation. Mortality from AKI is high due to incomplete knowledge of the pathogenesis of IRI and the lack of an effective therapy. Inflammation accompanies IRI and increases the blood level of C-reactive protein (CRP), a biomarker of worsened outcomes in AKI. To test if CRP is causal in AKI we subjected wild-type mice (WT) and human CRP transgenic mice (CRPtg) to bilateral renal IRI (both pedicles clamped for 30 min at 37°C then reperfused for 24 h). Serum human CRP level was increased approximately sixfold after IRI in CRPtg (10.62 ± 1.31 μg/ml at baseline vs. 72.01 ± 9.41 μg/ml at 24 h) but was not elevated by sham surgery wherein kidneys were manipulated but not clamped. Compared with WT, serum creatinine, urine albumin, and histological evidence of kidney damage were increased after IRI in CRPtg mice. RT-PCR analysis of mRNA isolated from whole kidneys of CRPtg and WT subjected to IRI revealed that in CRPtg kidneys 1) upregulation of markers of macrophage classical activation (M1 markers) was blunted, 2) downregulation of markers of macrophage alternative activation (M2 markers) was more robust, and 3) expression of the activating receptor FcγRI was increased. Our finding that CRP exacerbates IRI-induced AKI, perhaps by shifting the balance of macrophage activation and FcγR expression towards a detrimental portfolio, might make CRP a promising therapeutic target for the treatment of AKI.

Epidemiology of acute kidney injury in the intensive care unit

The incidence of acute kidney injury (AKI) in the intensive care unit (ICU) has increased during the past decade due to increased acuity as well as increased recognition. Early epidemiology studies were confounded by erratic definitions of AKI until recent consensus guidelines (RIFLE and AKIN) standardized its definition. This paper discusses the incidence of AKI in the ICU with focuses on specific patient populations. The overall incidence of AKI in ICU patients ranges from 20% to 50% with lower incidence seen in elective surgical patients and higher incidence in sepsis patients. The incidence of contrast-induced AKI is less (11.5%–19% of all admissions) than seen in the ICU population at large. AKI represents a significant risk factor for mortality and can be associated with mortality greater than 50%.

The protective effects of apocynin on kidney damage caused by renal ischemia/reperfusion

PURPOSE

This experimental study was designed to explore the protective effect of apocynin, the NADPH-oxidase inhibitor, on kidney damage induced by ischemia/reperfusion (I/R) in a rat model.

METHODS

Thirty-two rats were randomly divided into a control group and three I/R groups (1-hour ischemia followed by 23-hour reperfusion). Three I/R groups were treated by apocynin (20 mg/kg, i.p.) at two different time points (before ischemia and during ischemia). The histopathological findings, including apoptotic changes, and also tissue malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathion peroxidase (GPX), reduced glutathione (GSH), myeloperoxidase (MPO), blood urea nitrogen (BUN), and serum creatinine (Cr) levels, were determined.

RESULTS

Kidney tissue MDA and MPO, and serum BUN and Cr levels were found to be significantly higher in the I/R group, but there was no statistically significant difference in the levels of SOD, CAT, GPX, and GSH between the I/R and the control groups. Although apocynin significantly reduced MDA and MPO in group 3 and increased GPX in both treatment groups when compared to the I/R group, the elevated BUN and Cr levels were significantly reduced in treatment groups. Renal I/R injury also induced extensive tubular necrosis, glomerular damage, and apoptosis in the histological evaluation. Apocynin, especially when used during ischemia, ameliorated these histological damages in different amounts in treatment groups.

CONCLUSION

The beneficial effects of apocynin on renal I/R injury were evaluated for the first time.

Ureteric obstruction secondary to retroperitoneal fibrosis leading to acute kidney injury

A 65-year-old man presenting with apparent acute coronary syndrome was found to have an acute kidney injury. A CT scan of the abdomen revealed bilateral hydronephrosis secondary to retroperitoneal fibrosis, and an unruptured infrarenal abdominal aortic aneurysm Medical management with corticosteroids relieved the ureteric obstruction and renal function started to normalise within 72 h.

Contrast-induced acute kidney injury and renal support for acute kidney injury: a KDIGO summary (Part 2)

Acute kidney injury (AKI) is a common and serious problem affecting millions and causing death and disability for many. In 2012, Kidney Disease: Improving Global Outcomes completed the first ever international multidisciplinary clinical practice guideline for AKI. The guideline is based on evidence review and appraisal, and covers AKI definition, risk assessment, evaluation, prevention, and treatment. Two topics, contrast-induced AKI and management of renal replacement therapy, deserve special attention because of the frequency in which they are encountered and the availability of evidence. Recommendations are based on systematic reviews of relevant trials. Appraisal of the quality of the evidence and the strength of recommendations followed the Grading of Recommendations Assessment, Development and Evaluation approach. Limitations of the evidence are discussed and a detailed rationale for each recommendation is provided. This review is an abridged version of the guideline and provides additional rationale and commentary for those recommendation statements that most directly impact the practice of critical care.

Thyroid hormones for acute kidney injury

BACKGROUND

Acute kidney injury (AKI), which is common in hospitalised patients, is associated with significant morbidity and mortality. Despite recent advances in treatment, AKI outcomes have not changed substantially during the past four decades, and incidence is increasing. There is an urgent need to explore novel therapeutic agents and revisit some older drugs to review their roles in the management of AKI. Although thyroid hormone therapy has shown promise in experimental animal studies, clinical efficacy and safety have not been systematically assessed for the management of people with AKI.

OBJECTIVES

To evaluate the benefits and harms of thyroid hormones for the treatment of hospitalised adults with AKI of any aetiology.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register, CENTRAL, MEDLINE, and EMBASE. We also checked the reference lists of retrieved studies and articles.Date of search: November 2012

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs (in which allocation to treatment was obtained by alternation, use of alternate medical records, date of birth or other predictable methods) that compared any dose or form of thyroid hormone therapy alone or in combination with other agents compared with placebo or supplemental treatment (such as furosemide, dopamine, or atrial natriuretic peptide) in adult AKI patients.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. The quality of included studies was assessed using the Cochrane Collaboration's risk of bias assessment tool. For dichotomous outcomes (death, need for renal replacement therapy (RRT), progression to end-stage kidney disease (ESKD)), we planned to express results as risk ratios (RR) with 95% confidence intervals (CI). Where continuous scales of measurement were used to assess the effects of treatment (length of hospital stay, durations of AKI and RRT), we planned to use the mean difference (MD).

MAIN RESULTS

Two studies, enrolling 97 participants, met our inclusion criteria. The studies differed significantly in terms of study populations, natural history of AKI (multifactorial AKI in patients with native kidneys versus delayed graft function associated with acute tubular necrosis in transplant recipients), and study interventions; hence, data were not meta-analysed. One study reported a significant increase in the risk of all-cause mortality associated with thyroid hormone interventions compared with placebo (59 participants, RR 3.32, 95% CI 1.21 to 9.12); no deaths were reported in the other study. Both studies reported no significant difference in the need for RRT associated with thyroid hormone therapy when compared to placebo. Neither study reported incidence of progression to ESKD. There was a significantly longer duration of AKI (MD 2.00 days, 95% CI 0.18 to 3.82) and RRT (5.00 days, 95% CI 2.05 to 7.95) associated with thyroid hormone therapy compared with placebo in one study; no differences in durations of AKI (MD 2.00 days, 95% CI -3.53 to 7.53) and RRT (MD 2.00 days, 95% CI -2.36 to 6.36) were noted in the other study. One study reported similar lengths of stay in the intensive care unit and hospital in both intervention and control arms (MD -0.20 days, 95% CI -8.17 to 7.77); the other did not report this outcome. No adverse events were noted to be associated with thyroid hormone therapy in either study. Adequate data were not available to assess changes in kidney function or numbers of RRT sessions. Both included studies were small and methodological quality was suboptimal.

AUTHORS' CONCLUSIONS

We found a paucity of large, high quality studies to inform analysis of thyroid hormone interventions for the treatment of people with AKI. Current evidence suggested that thyroid hormone therapy may be associated with worse outcomes for patients with established AKI; therefore, its use for these patients should be avoided. The role of thyroid hormone therapy in preventing AKI has not been adequately investigated and may be considered in future clinical studies.

Purity and stability of online-prepared hemodiafiltration fluid after storage

BACKGROUND/AIMS

Previous studies have suggested that online hemodiafiltration (OL-HDF) fluid can be used as dialysate for continuous renal replacement therapies, and thus HDF costs can be reduced. The aims of this study were to determine the purity of OL-HDF fluid and to verify the stability of the electrolyte composition and acid-base balance during its storage.

METHODS

OL-HDF fluid was collected in 70 individual bags and stored for up to 7 days. The following tests were performed daily in 10 bags: natural visible precipitation (macrocrystallization), sample collection for chemical analysis and fluid culture, limulus amebocyte lysate endotoxin test, standard culture of NALGENE® filters after passing of the fluid, and molecular analysis of bacterial DNA.

RESULTS

The values of pH and pCO(2) showed a significant change starting at 24 h (p < 0.001); after 72 h, their values were beyond the measurable range. Coefficient of variation for pCO(2) was as high as 25.7%. Electrolyte composition (Na(+), K(+), Cl(-), Ca(2+) and glucose) showed a statistically significant difference over time (p < 0.05); however, their coefficients of variation were low (1.7, 1.4, 0.6, 2.3 and 0.9%, respectively), which might not be considered clinically significant. Negative results were obtained at all points by fluid and filter cultures, endotoxin test and molecular analysis. No macrocrystallization was observed at any time point.

CONCLUSIONS

We demonstrate the microbiological purity of OL-HDF fluid stored for up to 7 days. The electrolyte composition was stable, except for a relevant change in pCO(2) and consequently in pH (first noted at 24 h), emphasizing the need to reassess the acid-base balance in multilayer plastic bags in future studies.

Genetic deficiency of adiponectin protects against acute kidney injury

Adiponectin is a multifunctional cytokine that has a role in regulating inflammation. Here we determined if adiponectin modulates ischemic acute kidney injury. Compared with wild-type mice, adiponectin knockout mice were found to have lower serum creatinine and less tubular damage or apoptosis following ischemia/reperfusion injury. This latter process was associated with decreased Bax and reduced activation of p53 and caspase-3. Targeted disruption of adiponectin was also found to inhibit the infiltration of neutrophils, macrophages, and T cells into the injured kidneys. This was associated with an inhibition of NF-κB activation and reduced expression of the proinflammatory molecules IL-6, TNF-α, MCP-1, and MIP-2 in the kidney after ischemia/reperfusion injury. Wild-type mice engrafted with adiponectin null bone marrow had less kidney dysfunction and tubular damage than adiponectin null mice engrafted with wild-type bone marrow. Conversely, adiponectin null mice engrafted with wild-type bone marrow had similar renal dysfunction and tubular damage compared to wild-type mice engrafted with wild-type bone marrow. In cultured macrophages, adiponectin directly promoted macrophage migration; a process blocked by the PI3 kinase inhibitor, LY294002. Thus, our results show that adiponectin plays a pivotal role in the pathogenesis of acute renal ischemia/reperfusion injury and may be a potential therapeutic target.

Cortical Blindness due to Bilateral Occipital Infarcts in a Renal Failure Patient with Prostate Cancer: A Rare Complication of Hemodialysis

Loss of vision is a rare complication seen in hemodialysis patients. It is thought to develop because of the hypotension that can be observed during dialysis. This paper involves a patient with acute loss of vision during hemodialysis due to bilateral occipital infarcts.

Cardiorenal syndrome in critical care: the acute cardiorenal and renocardiac syndromes

Heart and kidney disease often coexist in the same patient, and observational studies have shown that cardiac disease can directly contribute to worsening kidney function and vice versa. Cardiorenal syndrome (CRS) is defined as a complex pathophysiological disorder of the heart and the kidneys in which acute or chronic dysfunction in one organ may induce acute or chronic dysfunction in the other organ. This has been recently classified into five subtypes on the basis of the primary organ dysfunction (heart or kidney) and on whether the organ dysfunction is acute or chronic. Of particular interest to the critical care specialist are CRS type 1 (acute cardiorenal syndrome) and type 3 (acute renocardiac syndrome). CRS type 1 is characterized by an acute deterioration in cardiac function that leads to acute kidney injury (AKI); in CRS type 3, AKI leads to acute cardiac injury and/or dysfunction, such as cardiac ischemic syndromes, congestive heart failure, or arrhythmia. Both subtypes are encountered in high-acuity medical units; in particular, CRS type 1 is commonly seen in the coronary care unit and cardiothoracic intensive care unit. This paper will provide a concise review of the epidemiology, pathophysiology, prevention strategies, and selected kidney management aspects for these two acute CRS subtypes.