The assessment of risk factors in 462 patients with acute renal failure

Acute kidney injury in nonagenarians: clinical characteristics and mortality

INTRODUCTION

Nonagenarians constitute a rising percentage of inpatients, with acute kidney injury (AKI) being frequent in this population. Thus, it is important to analyze the clinical characteristics of this demographic and their impact on mortality.

METHODS

Retrospective study of nonagenarian patients with AKI at a tertiary hospital between 2013 and 2022. Only the latest hospital admission was considered, and patients with incomplete data were excluded. A logistic regression analysis was conducted to define risk factors for mortality. A p-value < 0.05 was considered statistically significant.

RESULTS

A total of 150 patients were included, with a median age of 93.0 years (91.2-95.0), and males accounting for 42.7% of the sample. Sepsis was the most common cause of AKI (53.3%), followed by dehydration/hypovolemia (17.7%), and heart failure (17.7%). ICU admission occurred in 39.3% of patients, mechanical ventilation in 14.7%, vasopressors use in 22.7% and renal replacement therapy (RRT) in 6.7%. Death occurred in 56.7% of patients. Dehydration/hypovolemia as an etiology of AKI was associated with a lower risk of mortality (OR 0.18; 95% CI 0.04-0.77, p = 0.020). KDIGO stage 3 (OR 3.15; 95% CI 1.17-8.47, p = 0.023), ICU admission (OR 12.27; 95% CI 3.03-49.74, p < 0.001), and oliguria (OR 5.77; 95% CI 1.98-16.85, p = 0.001) were associated with mortality.

CONCLUSION

AKI nonagenarians had a high mortality rate, with AKI KDIGO stage 3, oliguria, and ICU admission being associated with death.

Low-Dose Sodium Nitrite Fluid Resuscitation Prevents Lethality From Crush Syndrome by Improving Nitric Oxide Consumption and Preventing Myoglobin Cytotoxicity in Kidney in A Rat Model

OBJECTIVE

Crush syndrome (CS) is a serious medical condition characterized by muscle cell damage resulting from pressure. CS has a high mortality, even when patients receive fluid therapy. We examined whether administration of NaNO2-containing fluid can improve survival in a rat model of CS.

DESIGN

The CS model was generated by subjecting anesthetized rats to bilateral hind limb compression with a rubber tourniquet for 5 h. Rats were then randomly divided into six groups: sham; CS with no treatment; CS with normal saline treatment; CS with normal saline + 25 mEq/L bicarbonate treatment; and CS with normal saline + 200 or 500 μmol/kg NaNO2.

MEASUREMENTS AND MAIN RESULTS

Blood and tissue samples were collected for histological and biochemical analyses at predetermined time points before and after reperfusion. Ischemic compression of rat hind limbs reduced nitrite content in the crushed muscle, and subsequent reperfusion resulted in reactive oxygen species-induced circulatory dysfunction and systemic inflammation. Rats treated with 200 μmol/kg NaNO2 showed increased nitric oxide (NO) levels, blood circulation, and neoangiogenesis, decreased generation of reactive oxygen species, and suppression of the inflammatory response, leading to complete recovery.

CONCLUSIONS

Treatment with 200 μmol/kg NaNO2 prevents muscle damage induced by ischemia reperfusion via the protective effects of NO and suppression of systemic inflammation, thereby increasing survival rates in CS.

Astragaloside-IV prevents acute kidney injury and inflammation by normalizing muscular mitochondrial function associated with a nitric oxide protective mechanism in crush syndrome rats

Background

Crush syndrome (CS) is a serious medical condition characterized by muscle cell damage resulting from decompression after compression (i.e., ischemia/reperfusion injury). A large number of CS patients develop cardiac failure, kidney dysfunction, and systemic inflammation, even when fluid therapy is administered. We evaluated whether the administration of astragaloside-IV (AS)-containing fluid improved survival by preventing kidney and muscular mitochondrial dysfunction in a rat model of CS.

Results

The CS model was generated by subjecting anesthetized rats to bilateral hind limb compression with a rubber tourniquet for 5 h. Rats were then randomly divided into four groups: (1) sham; (2) CS with no treatment; (3) CS with normal saline treatment; and (4) CS with normal saline + 10 mg/kg AS. AS-containing fluid improved kidney function by improving shock and metabolic acidosis in CS rats. In addition, there was a reduction in oxidative damage. The attenuation of hyperkalemia was significantly related to improving muscle injury via preventing mitochondrial dysfunction. Moreover, this mitochondria protection mechanism was related to the nitric oxide (NO) generated by activation of endothelial nitric oxide synthase, which provided an anti-oxidative and anti-inflammatory effect.

Conclusions

Treatment with AS-containing fluid led to a dramatic improvement in survival following CS because of direct and indirect anti-oxidative effects in the kidney, and improvements in mitochondrial dysfunction and inflammation owing to AS acting as an NO donor in injured muscle.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-017-0313-2) contains supplementary material, which is available to authorized users.

Serial APACHE III Scoring for Acute Renal Failure in the Intensive Care Unit

Severity stratification and prediction models are important tools for gauging outcomes in critically ill patients. However, most severity scoring systems are inaccurate when attempting to predict mortality in individuals with acute renal failure (ARF), including the APACHE (Acute Physiology and Chronic Health Evaluation) II scoring system. APACHE III scoring encompasses a greater array of physiologic parameters that may better correlate with outcome in ARF. We evaluated APACHE II and APACHE III scoring in 27 individuals admitted to the intensive acre unit (ICU) with ARF requiring dialysis. We also evaluated the predictive value of serial APACHE III scoring on mortality. Sixteen of the study subjects were discharged alive from the ICU. APACHE II scores for ICU survivors versus nonsurvivors were not significantly different at the outset of dialysis treatment, though they did discriminate between survivors and nonsurvivors at 48 hours (survivors 15 ± 6.2; nonsurvivors 18.1 ± 6.9; p = 0.019). However, average APACHE III scores for survivors were significantly less than those for nonsurvivors on all days of score collection, including at the outset of dialysis (day 0 survivors 94.7 ± 22.1; nonsurvivors 106.8 ± 21.7; p = 0.03). APACHE III scores on day 2 also discriminated between those who recovered renal function (83.6 ± 16.7) compared to those who did not (105.6 ± 21.4) (p = 0.05). Serial APACHE III scoring provided rapid and reproducible scoring that differentiated between survivors and nonsurvivors in a group of critically ill patients with ARF. This study suggests that further investigations are warranted to confirm whether serial APACHE III scoring should be considered as an adjunct clinical tool in caring for individuals with ARF in the ICU.

Improving acute kidney injury diagnostics using predictive analytics

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a multifactorial syndrome affecting an alarming proportion of hospitalized patients. Although early recognition may expedite management, the ability to identify patients at-risk and those suffering real-time injury is inconsistent. The review will summarize the recent reports describing advancements in the area of AKI epidemiology, specifically focusing on risk scoring and predictive analytics.

RECENT FINDINGS

In the critical care population, the primary underlying factors limiting prediction models include an inability to properly account for patient heterogeneity and underperforming metrics used to assess kidney function. Severity of illness scores demonstrate limited AKI predictive performance. Recent evidence suggests traditional methods for detecting AKI may be leveraged and ultimately replaced by newer, more sophisticated analytical tools capable of prediction and identification: risk stratification, novel AKI biomarkers, and clinical information systems. Additionally, the utility of novel biomarkers may be optimized through targeting using patient context, and may provide more granular information about the injury phenotype. Finally, manipulation of the electronic health record allows for real-time recognition of injury.

SUMMARY

Integrating a high-functioning clinical information system with risk stratification methodology and novel biomarker yields a predictive analytic model for AKI diagnostics.

Acute Renal Failure in Critically Ill Patients

Acute renal failure is an important cause of morbidity in critically ill patients. Acute renal failure results from pre renal and postrenal causes and, most importantly, acute tubular necrosis (ATN). Although it is known that renal toxins and renal ischemia are the most common causes of ATN in hospitalized patients, the exact pathogenesis of this entity is still not fully understood. Patients in the intensive care unit are at high risk for ATN because of hemodynamic instability, the administration of neph rotoxic antibiotics or chemotherapeutic agents, and ex posure to radiographic contrast agents. The acquired immunodeficiency syndrome is also associated with an increased risk of renal failure development, either from complications of the disease itself or from its treatment. Many consequences of acute renal failure such as vol ume overload, acidosis, hyperkalemia, and serositis can be managed adequately with peritoneal dialysis, hemo dialysis, or a newer technique, continuous arteriove nous hemofiltration. Despite improvements in treat ment, however, the mortality of ATN remains high. In this review, we recommend measures to prevent ATN in certain clinical situations that commonly occur among critically ill patients. We also review therapeutic options for treating patients in whom acute renal failure devel ops and discuss newer developments that may begin to reduce the excessive morbidity associated with ATN.

Risk Stratification for Acute Kidney Injury: Are Biomarkers Enough?

Acute kidney injury (AKI) is a common and serious complication that is associated with several adverse outcomes in hospitalized patients. AKI significantly increases the risk of mortality, need for renal replacement therapy, and intensive care admission, and it also has serious economic ramifications. Effective risk stratification to identify patients at risk for severe AKI is essential for targeting our health care and research resources to tackle this important public health issue. The overwhelming majority of research in earlier diagnosis and risk stratification of AKI over the past 10 years has focused on novel biomarker development. The purpose of this review is to provide an update on other novel risk stratification tools than can be used in the prognostication of AKI. We discuss the utility of the furosemide stress test in predicting the severity of AKI and the renal angina index in predicting the occurrence of AKI. We also discuss NephroCheck, a prognostic test that measures tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 for the early detection of severe AKI.

Medical causes of acute kidney injury- clinical and therapeutic aspects in constanta county

Introduction. Acute kidney injury represents an important clinical syndrome within nephrology, approximately 5% of hospitalised patients being affected. Establishing a diagnosis for acute kidney injury can be challenging and requires many steps. A complete and correct diagnosis is essential for appropriate therapy and, ultimately, the patient’s prognosis.

Methods. An objective of this study is to determine the presentation of certain characteristics for the diagnosis of acute kidney injury. It is also intended to show the therapeutic methods undertaken for patients presenting with acute kidney injury, as well as evolution under therapy.

Results. The most common causes of acute kidney injury were medical causes and within that category, cardiovascular diseases were the most common etiological factor (18%). Nephropathies represented a minority, with acute pyelonephritis, responsible for 5% of medical causes, and acute glomerulonephritis accounting for 6%. Hemodialysis was initiated only in 15% of patients. The rest of the patients were treated conservatively and responded favourably to this therapeutic approach. The etiological factors that had the greatest number of patients requiring hemodialysis were Rifampicin administration and leptospirosis (~20% each).

Conclusions. The clinical characteristics of acute kidney injury are variable and are usually specific to the etiology of the disease. The most common causes were cardiovascular diseases (18%). The therapeutic approach was rather conservative. Hemodialysis was instituted only in 15% of the patients. Almost 5% of all patients evolved to chronic kidney disease in a variable period of time, and the overall mortality was 18%, mainly due to infections and cardiovascular complications.

Management of crush victims in mass disasters: highlights from recently published recommendations

Crush syndrome is the second most common cause of death after earthquakes (the first most common is direct trauma). Many logistic problems with the treatment of patients with crush syndrome are due to chaotic disaster circumstances; consequently, medical and logistic recommendations on the treatment of crush victims are needed. In a joint initiative of the Renal Disaster Relief Task Force of the International Society of Nephrology and European Renal Best Practice, a work group of nephrologists, intensivists, surgeons, and logisticians with disaster experience or experts in guideline preparation collaborated to provide comprehensive information and recommendations on the management of crush casualties considering their occurrence with "epidemic" dimensions after mass disasters. The result is the monograph "Recommendations for the Management of Crush Victims in Mass Disasters", which may help provide effective health care to disaster victims with renal problems. This article discusses medical and logistic principles of the treatment of crush victims, both at the disaster field and on admission to hospitals, and guidance is described. The importance of early fluid administration even before extrication of the victims and avoidance of potassium-containing solutions during the treatment of crush victims is underlined. Also, the logistic problems in treating crush casualties are emphasized. The most important aspects of the recently published recommendations are highlighted.

Etiology and outcome of acute kidney injury in children

The aim of this prospective, multicenter study was to define the etiology and clinical features of acute kidney injury (AKI) in a pediatric patient cohort and to determine prognostic factors. Pediatric-modified RIFLE (pRIFLE) criteria were used to classify AKI. The patient cohort comprised 472 pediatric patients (264 males, 208 females), of whom 32.6% were newborns (median age 3 days, range 1-24 days), and 67.4% were children aged >1 month (median 2.99 years, range 1 month-18 years). The most common medical conditions were prematurity (42.2%) and congenital heart disease (CHD, 11.7%) in newborns, and malignancy (12.9%) and CHD (12.3%) in children aged >1 month. Hypoxic/ischemic injury and sepsis were the leading causes of AKI in both age groups. Dialysis was performed in 30.3% of newborns and 33.6% of children aged >1 month. Mortality was higher in the newborns (42.6 vs. 27.9%; p < 0.005). Stepwise multiple regression analysis revealed the major independent risk factors to be mechanical ventilation [relative risk (RR) 17.31, 95% confidence interval (95% CI) 4.88-61.42], hypervolemia (RR 12.90, 95% CI 1.97-84.37), CHD (RR 9.85, 95% CI 2.08-46.60), and metabolic acidosis (RR 7.64, 95% CI 2.90-20.15) in newborns and mechanical ventilation (RR 8.73, 95% CI 3.95-19.29), hypoxia (RR 5.35, 95% CI 2.26-12.67), and intrinsic AKI (RR 4.91, 95% CI 2.04-11.78) in children aged >1 month.

Acute kidney injury in the elderly

The aging kidney undergoes several important anatomic and physiologic changes that increase the risk of acute kidney injury (formerly acute renal failure) in the elderly. This article reviews these changes and discusses the diagnoses frequently encountered in the elderly patient with acute kidney injury. The incidence, staging, evaluation, management, and prognosis of acute kidney injury are also examined with special focus given to older adults.

Early Prognostic Factors in Patients with Acute Renal Failure Requiring Dialysis

PURPOSE

Despite improvements in renal therapy and technology, the mortality rate of patients with acute renal failure (ARF) remains high. Because ARF is a heterogeneous syndrome, occurring in patients with diverse etiologies and comorbid conditions, predicting its outcome is difficult. This study aims to identify early clinical and laboratory prognostic factors, including acute-phase reactants such as C-reactive protein (CRP), fibrinogen, and albumin, in ARF patients requiring dialysis.

MATERIAL AND METHODS

From June 2002 to March 2004, 61 patients with ARF requiring dialysis at Chang Gung Memorial Hospital, Chiayi, were prospectively analyzed. For each patient, the worst values of prognostic variables 24 hr before starting dialysis were prospectively assessed.

RESULTS

Oliguria, low plasma fibrinogen levels, hypotension, cardiac disease, and neoplastic disease were statistically significant in predicting hospital mortality. Using Youden's index, the best cut-off value for plasma fibrinogen in predicting mortality was 300 mg/dL with a sensitivity and specificity of 61% and 96%, respectively. Serum CRP and serum albumin were not predictive of hospital mortality.

CONCLUSION

Early prognostic factors in predicting mortality for patients with ARF requiring dialysis identified by multivariate logistic regression were oliguria, low plasma fibrinogen, hypotension, cardiac disease, and neoplastic disease. Serum CRP and albumin were not predictive of hospital mortality, whereas a plasma fibrinogen level < or =300 mg/dL had 61% sensitivity and 96% specificity in predicting mortality.

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

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

Prognostic value of acute physiology and chronic health evaluation II and organ system failure in patients with acute renal failure requiring dialysis

BACKGROUND

Despite advances in modern technology of dialysis, prognosis of patients with acute renal failure (ARF) remains poor. To give the clinicians the most useful information, a model that accurately predicts outcome early in the course of ARF is required. However, because ARF is a heterogeneous syndrome and occurs in patients with diverse etiologies and some coexisting diseases, predicting outcome early is hard. The aim of this study is to evaluate prospectively the Acute Physiology and Chronic Health Evaluation (APACHE II) and organ system failure (OSF) models, evaluated prior to dialysis, in predicting hospital mortality.

METHODS

From June 2002 to March 2004, ARF patients requiring dialysis at Chang Gung Memorial Hospital, Chiayi, were prospectively recruited for this study. The worst clinical and laboratory data in the 24 hours before initiation of dialysis were prospectively evaluated, and the patients' APACHE II score and OSF number were assessed.

RESULTS

A total of 61 patients (40 male and 21 female) were enrolled, of whom 38 (62.3%) died before discharge. By multivariate logistic regression, the APACHE II score (odds ratio 1.3 per increase in one score; P<0.001), or OSF number (odds ratio 1.9 per increase in one OSF; P<0.01) and oliguria (odds ratio 4.2; P=0.04), were found to be statistically significant prognostic factors for hospital mortality. Mortality increased progressively and significantly as OSF number (chi-square for trend; P=0.001) or the APACHE II score (chi-square for trend; P < 0.001) increased. By using Youden's index, the best cut-off value for APACHE II was 24, with 63% sensitivity and 96% specificity. The best cut-off value for OSF number was 2, with a sensitivity of 81.6% and a specificity of 60.9%. The areas under the receiver operating characteristic curves for APACHE II and OSF number were 0.847 (95% confidence interval (CI)=0.752-0.942; P<0.01) and 0.769 (95% CI=0.646-892; P<0.001), respectively, indicating good model discrimination.

CONCLUSIONS

This study concludes that APACHE II and OSF number measured prior to initiation of dialysis reliably predict outcomes of ARF patients requiring dialysis. The mortality rates increase as the APACHE II score or OSF number increases. For predicting mortality, the APACHE II score > or = 24 was found to have 63% sensitivity and 96% specificity, and OSF number> or = 2 had 81.6% sensitivity and 60.9% specificity.

The outcome of acute renal failure in the intensive care unit according to RIFLE: model application, sensitivity, and predictability

BACKGROUND

The definition, classification, and choice of management of acute renal failure (ARF) in the setting of the intensive care unit (ICU) remain subjects of debate. To improve our approach to ARF in the ICU setting, we retrospectively applied the new classification of ARF put forward by the Acute Dialysis Quality Initiative group, RIFLE (acronym indicating Risk of renal failure, Injury to the kidney, Failure of kidney function, Loss of kidney function, and End-stage renal failure), to evaluate its sensitivity and specificity to predict renal and patient outcomes.

METHODS

RIFLE classification was applied to 183 patients with ARF admitted to the ICU (2002 to 2003) at the Northern General Hospital, Sheffield, UK. Patients were divided into 4 groups according to percentage of decrease in glomerular filtration rate from baseline. The risk group included 60 patients; injury group, 56 patients; failure group, 43 patients; and control group, 24 patients. Demographic, biochemical, hematologic, clinical, and long-term health status were studied and compared in the 4 groups. An attempt was made to evaluate, by means of logistic regression analysis and receiver operator characteristic curve analysis, the predictive value of RIFLE classification for mortality in the ICU.

RESULTS

The failure group showed the worst parameters with regard to Acute Physiology and Chronic Health Evaluation (APACHE) II score, pH, lowest and highest mean arterial pressures, and Glasgow Coma Scale (P < 0.001). Mortality rate in the ICU (1 month) was significantly greater in the failure group compared with all groups (32 of 43 patients [74.4%]; P < 0.001) and, again, 6-month mortality rate (37 of 43 patients [86%]; P < 0.001). Receiver operator characteristic curve analysis showed that Simplified Acute Physiology Score (SAPS) II was more sensitive than APACHE II score for prediction of patient death in the risk and injury groups compared with the failure and control groups (risk group: SAPS II, 0.8 +/- 0.06; P < 0.001; APACHE II, 0.63 +/- 0.07; P = 0.14; injury group: SAPS II, 0.76 +/- 0.08; P < 0.001; APACHE II, 0.72 +/- 0.07; P = 0.006).

CONCLUSION

RIFLE classification can improve the ability of such older and established ICU scoring systems as APACHE II and SAPS II in predicting outcome of ICU patients with ARF.

External validation of severity scoring systems for acute renal failure using a multinational database

OBJECTIVE

Several different severity scoring systems specific to acute renal failure have been proposed. However, most validation studies of these scoring systems were conducted in a single center or in a small number of centers, often the same ones used for their development. Therefore, it is not known whether such severity scoring systems may be widely applied.

DESIGN

Prospective clinical investigation.

SETTING

Intensive care units.

PATIENTS

One thousand seven hundred and forty-two intensive care unit patients with acute renal failure who were either treated with renal replacement therapy or fulfilled predefined criteria.

INTERVENTIONS

Demographic and clinical information and outcomes were measured.

MEASUREMENTS AND MAIN RESULTS

Scores for four acute renal failure-specific scoring systems and two general scoring systems (Simplified Acute Physiology Score II and Sequential Organ Failure Assessment) were calculated, and their discrimination and calibration were tested with receiver operating characteristic curves and Hosmer-Lemeshow goodness-of fit-tests. For the receiver operating characteristic curves, blood lactate levels were also used as a reference. All scores had an area under the receiver operating characteristic curve <0.7 (Mehta 0.670, Liano 0.698, Chertow 0.610, Paganini 0.643, Simplified Acute Physiology Score II 0.645, Sequential Organ Failure Assessment 0.675, lactate 0.639). For scores that can calculate predicted mortality, the Hosmer-Lemeshow goodness-of-fit test showed poor calibration.

CONCLUSIONS

None of the scoring systems tested had a high level of discrimination or calibration to predict mortality for patients with acute renal failure when tested in a broad cohort of patients from multiple countries. A large, multiple-center database might be needed to improve the discrimination and calibration of acute renal failure scoring system.

Has mortality from acute renal failure decreased? A systematic review of the literature

PURPOSE

To determine mortality rates in patients with acute renal failure during the past decades.

METHODS

We performed a MEDLINE search using the keywords "acute renal failure" crossed with "outcome," "mortality," "ICU," "critically ill" or "prognosis" in the period from January 1970 to December 2004. Abstracts and full articles were eligible if mortality rates were reported. We also reviewed the bibliographies of available studies for further potentially eligible studies. The dates of the observation period for each study and not the publication dates were considered for the analysis, so the earliest data were from 1956.

RESULTS

Of 85 articles fulfilling the criteria, 5 were excluded because of duplicate publications using the same database, so that 80 were included in our review with a total of 15897 patients. Mortality rates in most studies exceeded 30%, and there was no consistent change over time.

CONCLUSION

Despite technical progress in the management of acute renal failure over the last 50 years, mortality rates seem to have remained unchanged at around 50%.

Evaluation of prognostic indexes in critical acute renal failure patients

OBJECTIVE

To study different prognostic indexes in acute renal failure (ARF) patients admitted to an intensive care unit (ICU).

DESIGN

Prospective, cohort study. Individual Severity Score-Acute Tubular Necrosis (ISS-ATN) obtained prospectively and retrospectively, Acute Physiologic and Chronic Health Evaluation (APACHE II) Score, APACHE II Risk, Lung Injury Score (LIS), and Number of Organ Failures (NOF) were calculated for each patient. The outcome analyzed was death in the ICU. Discrimination was evaluated by the area under the receiver operator characteristic curve (AUC). For calibration analysis, the chi-square goodness-of-fit test was used to compare predicted mortality, calculated by ISS-ATN (obtained prospectively or retrospectively) and APACHE II risk, with observed mortality.

SETTING

ICU, São Rafael Hospital, Salvador-BA, Brazil.

PATIENTS

Seventy-six ARF patients admitted to the ICU within 6 months.

INTERVENTIONS

Surgical and medical procedures.

MEASUREMENTS AND RESULTS

The observed AUC was 0.69 for LIS, 0.73 for prospective ISS-ATN, 0.75 for retrospective ISS-ATN, 0.76 for APACHE II Score, 0.78 for APACHE II Risk, and 0.88 for NOF. These areas were significantly different from 0.5 (p < .001). There was no difference between the observed and expected death rate calculated by ISS-ATN. However, APACHE II underestimated the observed mortality (p < .001).

CONCLUSION

The prognostic indexes studied showed good discriminative power. However, APACHE II was not well calibrated in contrast to the good calibration of ISS-ATN.

Acute renal failure in the surgical setting

Acute renal failure (ARF) is an unwelcome complication of major surgical procedures that contributes to surgical morbidity and mortality. Acute renal failure associated with surgery may account for 18-47% of all cases of hospital-acquired ARF. The overall incidence of ARF in surgical patients has been estimated at 1.2%, although is higher in at-risk groups. Mortality of patients with ARF remains disturbingly high, ranging from 25% to 90%, despite advances in dialysis and intensive care support. Appreciation of at-risk surgical populations coupled with intensive perioperative care has the capacity to reduce the incidence of ARF and by implication mortality. Developments in understanding the pathophysiology of ARF may eventually result in newer therapeutic strategies to either prevent or accelerate recovery from ARF. At present the best form of treatment is prevention. In this review the epidemiology, pathophysiology, diagnosis, treatment and possible prevention of ARF will be discussed.

Worsening renal function: what is a clinically meaningful change in creatinine during hospitalization with heart failure?

INTRODUCTION

Worsening renal function during hospitalization for heart failure, defined as elevation in creatinine during admission, predicts adverse outcomes. Prior studies define worsening renal function using various creatinine elevations, but the relative value of definitions is unknown.

METHODS AND RESULTS

In a prospective cohort of 412 patients hospitalized for heart failure, we compared a spectrum of worsening renal function definitions (absolute creatinine elevations >/=0.1 to >/=0.5 mg/dL and 25% relative elevation from baseline) and associations with 6-month mortality, readmission, and functional decline. Creatinine elevation >/=0.1 mg/dL occurred in 75% of patients, and elevation >/=0.5 mg/dL occurred in 24% of patients. Risk of death rose with higher creatinine elevations (adjusted hazard ratio [HR] = 0.89, 1.19, 1.67, 1.91, and 2.90 for elevations >/=0.1 to >/=0.5 mg/dL). Maximum sensitivity of any definition for predicting mortality was 75% and maximum specificity was 79%. High creatinine elevation was a more important predictor of death than was a single measure of baseline creatinine.

CONCLUSIONS

Larger creatinine elevations predict highest risk of death, yet even minor changes in renal function are associated with adverse outcomes. The choice of a "best definition" for worsening renal function has implications for the number of patients identified with this risk factor and the magnitude of risk for mortality.

Low-flux versus high-flux synthetic dialysis membrane in acute renal failure: prospective randomized study

The influence of dialyzer membrane on the morbidity and mortality of patients with acute renal failure remains a matter of debate. The aim of the prospective randomized clinical study was to assess the influence of the flux of a synthetic dialyzer membrane on patients' survival rate, restitution of renal function, and duration of hemodialysis treatment of patients with acute renal failure as a part of multiorgan failure. Seventy-two patients treated in intensive care units of the University Medical Center Ljubljana were randomized according to the dialyzer used throughout the duration of hemodialysis treatment. There were 38 patients in the low-flux group (dialyzer F6, low-flux polysuphone, Fresenius, Bad Homburg, Germany) and 34 patients in the high-flux group (dialyzer Filtral 12, sulphonated high-flux polyacrylonitrile, Hospal, Industrie Meyzieu, France). Both groups were balanced in terms of sex, age, APACHE II score, oliguria before dialysis, cause of acute renal failure, inotropic support, mechanical ventilation, and the number of failing organs. The patients' survival rate was 18.7% in the low-flux group and 20.6% in the high-flux group. Ten patients (26.3%) recovered their renal function in the low-flux group and 8 (23.5%) in the high-flux group. Hemodialysis treatment lasted 11.2 days in the low-flux and 10.7 days in the high-flux group. An analysis of subgroups with a lower mortality rate (subgroup of patients without oliguria and subgroup of patients with less than 4 failed organ systems) did not show significant differences between the low-flux and high-flux groups in terms of survival rate, recovery of renal function, and duration of hemodialysis treatment. In conclusion, no significant differences were found in the results of low-flux versus high-flux synthetic membrane dialyzer treatment in patients with acute renal failure as a part of multiorgan failure in terms of survival rate, recovery of renal function, incidence of oliguria during hemodialysis, and duration of hemodialysis treatment. The number of failing organs seems to be the most important single factor determining the survival of patients with acute renal failure as a part of multiorgan failure.

Incidence, risk factors, and prognosis of gastrointestinal hemorrhage complicating acute renal failure

BACKGROUND

Few prospective data are currently available on acute gastrointestinal hemorrhage (AGIH) as a complication of acute renal failure (ARF). The aim of the present study was to define incidence, sources, risk factors, and outcome of AGIH in patients with ARF.

METHODS

We performed a prospective study on an inception cohort of 514 patients admitted for ARF to a nephrology intermediate care unit. Data on clinical risk factors for bleeding, frequency of occurrence of AGIH, length of hospital stay, and in-hospital mortality were collected. Independent predictors of AGIH were identified. The relative odds of death and the relative increase in length of hospital stay associated with AGIH were calculated after adjusting for baseline comorbidities.

RESULTS

Sixty-nine patients out of 514 [13.4% (95% CI, 10.6 to 16.7)] had AGIH as a complication of ARF; 59 were upper AGIH. Forty patients had clinically important bleeding. Erosions and/or ulcers accounted for 71% of cases of upper AGIH. Independent baseline predictors of AGIH were represented by severity of illness [odds ratio 1.45 (95% CI, 1.05 to 2.01) for every 10 point increase in APACHE II score], low platelet count [<50,000 mm3; 3.71 (1.70 to 8.11)], noncirrhotic chronic hepatic disease [2.22 (1.09 to 4.55)], liver cirrhosis [3.38 (1.50 to 7.60)], de novo ARF [2.77 (1.30 to 5.90)], and severe ARF [2.07 (1.10 to 3.88)]. In-hospital mortality was 63.8% in patients with AGIH and 34.2% in the other patients; after adjusting for baseline confounders, AGIH remained significantly associated with an increase in both mortality [2.57 (1.30 to 5.09), P = 0.006] and length of hospital stay [37% (1 to 87%), P = 0.047].

CONCLUSIONS

AGIH and clinically important bleeding are frequent complications of ARF. In this clinical condition, AGIH is more often due to upper gastrointestinal bleeding and is associated with a significantly increased risk of death and length of hospital stay. Both renal and extrarenal risk factors are related to the occurrence of AGIH.

Acute renal failure and dialysis in the chronically critically ill patient

Acute renal failure is a common clinical problem in the intensive care unit (ICU) and is associated with significant morbidity and mortality. There is no "magic bullet" to prevent acute renal failure or to modify the clinical course of established renal failure. The approach to therapy is directed to the early initiation of dialysis therapy. Continuous dialysis therapy is becoming the preferred form of dialysis in the ICU.

Patient survival and renal recovery in acute renal failure: randomized comparison of cellulose acetate and polysulfone membrane dialyzers

OBJECTIVE

To investigate survival and renal recovery after dialysis in patients with acute renal failure with use of synthetic membranes compared with substituted cellulose membranes.

PATIENTS AND METHODS

We prospectively studied survival and recovery of renal function of 66 patients with acute renal failure who required intermittent hemodialysis. Patients were randomized to exclusive treatment with either cellulose acetate (CA) or polysulfone (PS) hemodialysis membranes. Additionally, markers of biocompatibility (complement, leukocyte counts, cytokine concentration) were measured at initiation and 1 hour after initiation of dialysis among 10 patients equally distributed between the CA and PS groups.

RESULTS

The cohorts were indistinguishable with respect to age, sex, presence of diabetes mellitus, Acute Physiology and Chronic Health Evaluation II scores, percentage in the intensive care unit (ICU), and adequacy of dialysis. Survival (76% CA, 73% PS; P=.78) and recovery of renal function at 30 days (58% CA, 39% PS; P=.14) were not statistically different in the 2 groups. Among 26 CA patients and 27 PS patients treated in the ICU, survival was not statistically different (73% CA, 67% PS; P=.61); however, the proportion of patients recovering renal function suggested a benefit favoring CA membranes (65% CA, 37% PS; P=.04). Additionally, markers of biocompatibility were not significantly different between groups among the 10 patients equally distributed between the CA and PS groups.

CONCLUSIONS

Overall clinical outcomes among patients with acute renal failure treated with CA hemodialysis membranes and those treated with PS membranes were not significantly different. The observed advantage favoring renal recovery among this ICU population treated with CA hemodialysis membranes warrants further investigation.

Correlates and impact on outcomes of worsening renal function in patients > or =65 years of age with heart failure

1.5 mg/dl. Based on the number of these factors, a patient's risk for developing worsening renal function ranged between 16% (< or =1 factor) and 53% (> or =5 factors). After adjusting for confounding effects, worsening renal function was associated with a significantly longer length of stay by 2.3 days, higher in-hospital cost by $1,758, and an increased risk of in-hospital mortality (odds ratio 2.72; 95% confidence interval 1.62 to 4.58). In conclusion, worsening renal function, an event that frequently occurs in elderly patients hospitalized with heart failure, confers a substantial burden to patients and the healthcare system and can be predicted by 6 admission characteristics.

An analysis of excess mortality not predicted to occur by APACHE III in an Australian level III intensive care unit

The APACHE III derived standardized mortality ratio has been suggested as a statistic to measure intensive care unit (ICU) effectiveness. From 1991 data collected on 519 consecutive admissions to the Royal Adelaide Hospital ICU a standardized mortality ratio of 1.25 was calculated. Of the 174 deaths only 95 had a prediction of death greater than 0.5. As part of a quality assurance study we undertook a retrospective case note audit to try to identify factors that were associated with the low mortality prediction (< 0.5) in hospital deaths. Firstly we analysed the patient population that died to determine the factors that were different between patients who had a mortality prediction of greater than 0.5 versus those who had a mortality prediction of less than 0.5. Next we analysed the patient population with a mortality prediction of less than 0.5 and compared actual survivors with patients who died in hospital. Amongst low mortality prediction patients admitted to the Royal Adelaide Hospital ICU we identified age, a history of acute myocardial infarction, presentation to ICU after a cardiac arrest or with an elevated creatinine and the development of acute renal failure and septicaemia during the ICU admission as being associated with in-hospital mortality. We also documented that late hospital deaths on the ward after ICU discharge occurred more frequently with low predicted hospital mortality ICU patients. Factors other than the APACHE III score may be associated with hospital deaths of ICU patients.

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.

Role of hypoalbuminemia and hypocholesterolemia as copredictors of mortality in acute renal failure

Role of hypoalbuminemia and hypocholesterolemia as co-predictors of mortality in acute renal failure.

BACKGROUND

Hypoalbuminemia (LA) and hypocholesterolemia (LC) have been reported to portend high mortality in both older patients and in patients with end-stage renal disease. Even though low levels have been reported in critically ill patients, they have not been clearly defined as predictors of mortality in acute renal failure (ARF). The impact of LA and LC on mortality in ARF is evaluated in this study.

METHODS

We conducted a computer-assisted three-year retrospective review of all cases of de novo ARF seen at an inner city tertiary-care facility. One hundred cases met the criteria for inclusion in the study. We employed both univariate and multivariate logistic regression models to estimate the relative risks (RR) and 95% confidence intervals (CI) of mortality associated with several variables.

RESULTS

Predictors associated with a high risk of death identified in this study include LC < or = 150 mg/dl (< or = 3.9 mmol/liter; RR, 7.4; CI, 2.7 to 20.3), LA < or =35 g/liter (RR, 5.0; CI, 1.9 to 13.2), sepsis (RR, 9.4; CI, 3.7 to 23.9), mechanical ventilation (RR, 10.8; CI, 2.8 to 41.0), oliguria (RR 17.0; CI, 6.2 to 46.6), and multisystem organ failure (RR 24.7; CI, 10.3 to 59.1). The overall gross mortality was 39%, but mortality among intensive care unit patients was 82%. Survival was 82% among patients with serum albumin >35 g/liter versus 48% among those with serum albumin < or =35 g/liter (chi2 = 11.9, P = 0.0006). Similarly, survival was higher among patients with cholesterol >150 mg/dl (>3.9 mmol/liter) than those whose levels were < or =150 mg/dl (< or =3.9 mmol/liter; 85 vs. 44%, ch 17.3, P<0.0001). Significant association between LA and LC was observed (R = 0.4, P<0.0001). Age, gender, level of plasma creatinine, and underlying chronic medical conditions were not predictive of mortality.

CONCLUSION

Survival in ARF is significantly altered by the levels of albumin and cholesterol. Because both LC and LA can be cytokine mediated, their presence in ARF should be considered ominous.

Acute renal failure in the cardiac care unit: etiologies, outcomes, and prognostic factors

BACKGROUND

Heart disease is a leading cause of hospitalizations, and its prevalence is expected to grow rapidly over the next few decades. The purpose of this study was to examine the incidence, etiologies, outcomes, and risk factors for mortality of acute renal failure (ARF) in cardiac care unit (CCU) patients.

METHODS

A retrospective, cohort study examining all patients who developed ARF while in the CCU at Barnes-Jewish Hospital over a 17-month time period was performed. Charts were reviewed to determine etiologies, hospital mortality rates, and risk factors for mortality.

RESULTS

Four percent of admissions to the CCU met criteria for ARF while in the unit. The etiologies of ARF were congestive heart failure (CHF; 35%), multifactorial (usually involving CHF; 26%), arrest/arrhythmia (13%), contrast (11%), volume depletion (6%), sepsis (6%) and obstruction (3%). The mortality rate was 50%. Oliguria, mechanical ventilation, and decreased cardiac function were statistically significant risk factors for mortality by univariate but not multivariate analysis. Thirty percent of patients with a cardiac index of less than 2.0 liter/min/m2 survived to discharge.

CONCLUSIONS

ARF occurs commonly in CCU patients and is associated with a high mortality rate. However, there are a significant number of survivors even among patients with severely depressed cardiac function.

Prevalence and clinical outcome associated with preexisting malnutrition in acute renal failure: a prospective cohort study

Malnutrition is a frequent finding in hospitalized patients and is associated with an increased risk of subsequent in-hospital morbidity and mortality. Both prevalence and prognostic relevance of preexisting malnutrition in patients referred to nephrology wards for acute renal failure (ARF) are still unknown. This study tests the hypothesis that malnutrition is frequent in such clinical setting, and is associated with excess in-hospital morbidity and mortality. A prospective cohort of 309 patients admitted to a renal intermediate care unit during a 42-mo period with ARF diagnosis was studied. Patients with malnutrition were identified at admission by the Subjective Global Assessment of nutritional status method (SGA); nutritional status was also evaluated by anthropometric, biochemical, and immunologic parameters. Outcome measures included in-hospital mortality and morbidity, and use of health care resources. In-hospital mortality was 39% (120 of 309); renal replacement therapies (hemodialysis or continuous hemofiltration) were performed in 67% of patients (206 of 309); APACHE II score was 23.1+/-8.2 (range, 10 to 52). Severe malnutrition by SGA was found in 42% of patients with ARF; anthropometric, biochemical, and immunologic nutritional indexes were significantly reduced in this group compared with patients with normal nutritional status. Severely malnourished patients, as compared to patients with normal nutritional status, had significantly increased morbidity for sepsis (odds ratio [OR] 2.88; 95% confidence interval [CI], 1.53 to 5.42, P < 0.001), septic shock (OR 4.05; 95% CI, 1.46 to 11.28, P < 0.01), hemorrhage (OR 2.98; 95% CI, 1.45 to 6.13, P < 0.01), intestinal occlusion (OR 5.57; 95% CI, 1.57 to 19.74, P < 0.01), cardiac dysrhythmia (OR 2.29; 95% CI, 1.36 to 3.85, P < 0.01), cardiogenic shock (OR 4.39; 95% CI, 1.83 to 10.55, P < .001), and acute respiratory failure with mechanical ventilation need (OR 3.35; 95% CI, 3.35 to 8.74, P < 0.05). Hospital length of stay was significantly increased (P < 0.01), and the presence of severe malnutrition was associated with a significant increase of in-hospital mortality (OR 7.21; 95% CI, 4.08 to 12.73, P < 0.001). Preexisting malnutrition was a statistically significant, independent predictor of in-hospital mortality at multivariable logistic regression analysis both with comorbidities (OR 2.02; 95% CI, 1.50 to 2.71, P < 0.001), and with comorbidities and complications (OR 2.12; 95% CI, 1.61 to 2.89, P < 0.001). Malnutrition is highly prevalent among ARF patients and increases the likelihood of in-hospital death, complications, and use of health care resources.

Treatment of acute renal failure

Acute renal failure is a life threatening illness whose mortality has remained high since the introduction of hemodialysis 25 years ago, despite advances in supportive care. Acute renal failure is an extremely morbid and costly disorder with a significant proportion of patients progressing to end-stage renal disease requiring dialysis. To the nephrologist, acute renal failure remains an extremely frustrating disease, because the pathophysiology is not well understood and the limited therapeutic options force the nephrologist to sit on the sidelines and wait for renal function to return. For example, dialysis remains the only FDA-approved treatment for acute renal failure, but dialysis may also cause renal injury that prolongs renal failure. The purpose of this perspective is to understand the results of the recent, largely negative, clinical trials in view of recent advances in the epidemiology of ARF. This review will also discuss diagnostic tools, strategies for improved design of clinical trials, and other therapeutic interventions that will be needed to properly treat acute renal failure in the 21st century.

Impact of acute renal failure on mortality in end-stage liver disease with or without transplantation

BACKGROUND

Acute renal failure (ARF) is traditionally considered a poor prognostic factor in end-stage liver disease and is associated with a mortality approaching 90%. While the increased use of orthotopic liver transplantation (OLTX) has changed the outcome for patients with end-stage liver disease (ESLD), it is not clear whether this has affected the outcome of patients with ESLD and ARF.

METHODS

We prospectively followed the course of ARF in 177 patients with ESLD being evaluated for OLTX. Of these patients 111 received OLTX. In-hospital mortality was compared to that of 316 ESLD patients without ARF, of these 196 received OLTX. Variables include severity of illness as assessed by APACHE II, co-morbid conditions, oliguria, need for renal replacement therapy, and etiologies of ESLD and ARF. These variables were evaluated with respect to the outcome in-hospital mortality by multiple regression analysis for patients with ARF.

RESULTS

Mortality was significantly higher in oliguric versus non-oliguric patients and in patients who required renal replacement therapy. Mortality correlated strongly with the number of co-morbid conditions, especially sepsis, encephalopathy, respiratory failure, and DIC. For OLTX recipients who developed ARF, no significant difference in survival occurred whether the ARF was pre-OLTX or post-OLTX.

CONCLUSION

ARF was associated with an increased mortality consistent with the known adverse prognostic effect of ARF in ESLD. However, the effect of ARF on mortality was remarkably reduced in patients who received a functioning OLTX. Since expected mortality generated from APACHE II scores was higher in the ARF groups, it is not clear that there is an additional effect of ARF beyond the physiologic derangements captured by APACHE II. ARF per se should not necessarily be a contraindication to liver transplant.

Causes and prognosis of acute renal failure in the very old. Madrid Acute Renal Failure Study Group

OBJECTIVES

There is a tendency to treat older people with Acute Renal Failure (ARF) less aggressively because of the presumed less acceptable end results. This has not been proved, and their prognosis may be similar to that found in the younger population. There are no studies on the incidence, causes, and evolution of ARF in patients 80 years of age and older.

DESIGN

A multicenter, prospective, longitudinal study.

SETTING

The 13 hospitals with nephrology units that serve the 4.2 million people in Madrid, Spain.

MEASUREMENTS

A number of demographic, clinical, and therapeutic variables were studied in each case.

RESULTS

One hundred three episodes of ARF occurred in patients 80 years of age and older (Group 1), 256 in patients aged 65 to 79 years (Group 2), and 389 in people younger than age 65 (Group 3). Acute tubular necrosis was diagnosed in 39% of cases in Group 1, in 48% in Group 2, and in 55% in Group 3 (P = .004, 1 vs 3); prerenal ARF was diagnosed in 30%, 28%, and 21% (P = .054, 1 vs 3) and obstructive ARF in 20%, 11%, and 7% (P < .001, 1 vs 3) of cases, respectively. Serum creatinine at admission, peak values, values at discharge or death, duration of both admission and ARF episode, and mortality were similar in all groups. In stratified analysis, relative risk for mortality in patients aged more than 80 years was 1.09 [95%CI 0.86,1.36 (P = .562)], and in those aged 65 to 79 it was 0.99 [95%CI 0.83,1.18 (P = .954)] compared with patients aged less than 65 years. Risk of death was also similar when only acute tubular necrosis cases were considered. Sustained hypotension was associated with higher mortality (44% of nonsurviving older persons vs 9% of survivors, P < .001).

CONCLUSION

Age is not a particularly poor prognostic sign, and outcome seems to be within acceptable limits for very old patients with ARF. Acute dialysis should not be withheld from patients solely because they are more than 80 years of age.

A simple and early prognostic index for acute renal failure patients requiring renal replacement therapy

Recent advances in technology have not substantially changed the high mortality rate associated with acute renal failure (ARF). To obtain a simple, valid prognostic index, we retrospectively evaluated the relative importance of demographic data, causes (acute insults) of renal failure, and comorbid clinical conditions for the outcome in 102 ARF patients who received renal replacement therapy with an overall mortality rate of 65% (66 of 102). There were no significant differences between survivors and nonsurvivors in age and gender. Mortality according to acute insults was similar to that of the whole population studied. Of the 10 clinical conditions at the time of the first renal replacement therapy, mechanical ventilation (p = 0.0002), cardiac failure (p = 0.0006), hepatic failure (p = 0.003), central nervous system dysfunction (p = 0.005), and oliguria (p = 0.04) were found to be significantly related to mortality by univariate analysis. Furthermore, multivariate analysis demonstrated that only mechanical ventilation, cardiac failure, and hepatic failure were significant risk factors. Survival was directly related to the number of significant variables in univariate analysis: zero, 89% (8 of 9); one, 62% (21 of 34); two, 19% (5 of 27); three, 10% (2 of 20); four, 0% (0 of 8); five, 0% (0 of 4). This simple and early prognostic index, derived from the assessment of clinical conditions which were easily determined at the patient's bedside, could be useful for outcome prediction in ARF patients requiring renal replacement therapy.

The nature of renal cell injury

The main functional change in patients with acute renal failure (ARF) is a decrease in glomerular filtration rate (GFR). The virtual complete recovery of renal function in those patients who survive ARF, as well as the minimal renal histological abnormalities during ARF when the GFR is less than 10 ml/min, suggest that a major component of the renal tubular cell injury is sublethal or reversible. Experimental models of acute tubular necrosis frequently have placed the emphasis on irreversible proximal tubular cell death. The nature of the renal tubular cell injury in ischemic acute renal failure, however, includes not only cell death (necrosis or apoptosis) but also sublethal injury causing cell dysfunction. The role of intracellular calcium, the calcium-dependent enzymes calpain, phospholipase A2 and nitric oxide synthase (NOS), in the pathophophysiology of this renal tubular cell injury during hypoxia/ischemia is described. The effects of calpain and nitric oxide (NO) on the cytoskeleton and cell adhesion are discussed. Potential mechanisms whereby tubular injury leads to a profound fall in GFR, including increased tubuloglomerular feedback and increased distal tubular obstruction, in ischemic acute renal failure are proposed.

Acute renal failure in recipients of organ transplantation and nontransplantation patients: comparison of characteristics and mortality

Mortality from acute renal failure in critically ill patients remains in excess of 50% despite decades of improvement in supportive care. It is not known whether replacement of other failing organs by non-renal organ transplantation affects mortality in acute renal failure. We retrospectively reviewed the course of 169 patients with acute renal failure managed at a single university medical center over a 1-year period. Measures of disease severity (need for renal replacement therapy, mechanical ventilation or parenteral nutrition, presence of oliguria and APACHE II scores) and final outcome were compared in 97 patients with acute renal failure who did not receive transplants and 72 patients with acute renal failure who underwent non-renal solid organ transplants. Overall mortality was 50.3% and directly correlated with APACHE II score. Compared to nontransplant patients, transplant recipients were younger. more frequently male, and less often oliguric; but the groups were similar in mean APACHE II scores and need for renal replacement therapy, prolonged mechanical ventilation, and parenteral nutrition. Overall, mortality was significantly lower for transplant patients compared to nontransplant patients (34.7% vs. 61.9%, p < 0.05). In nonoliguric acute renal failure and renal failure not requiring renal replacement therapy, mortality was low and similar in both transplant and nontransplant patients. Compared to nontrasplant patients with similar risk factors and similar APACHE II scores, mortality was significantly lower for transplant patients who were oliguric, or who required renal replacement therapy, mechanical ventilation, or parenteral nutrition. Organ transplantation is associated with a survival advantage in acute renal failure when compared to the outcome of critically ill nontransplant patients. The relation between APACHE II scores and survival is altered by transplantation.

Acute renal failure in renal allograft recipients and patients with native kidneys

In order to evaluate the role of underlying disease in the high mortality observed in acute renal failure (ARF) and risk factors related to the development of oliguric ARF in renal allograft recipients, two groups were selected: 34 patients with native kidneys, aged 16 and 57 years, and presenting ischemic ARF caused by cardiovascular collapse, with no signs of infection at the time of diagnosis; and 34 renal allograft recipients who developed ARF immediately after transplantation, without rejection. ARF was defined either as 30% increase of basal plasmatic creatinine in patients with native kidneys or nonnormalization of plasmatic creatinine at day 5 after transplantation in renal allograft recipients; oliguria as diuresis < or = 400 mL/24 h. There were no differences in age, male frequency, oliguria presence and duration, need for dialysis, and infection episodes for renal allograft recipients and patients with native kidneys. The development of sepsis (3% and 41%) and death rate (3% and 44%) were higher in patients with native kidneys (p < 0.01). The renal allograft recipients with both oliguric (n = 18) and nonoliguric (n = 16) ARF were evaluated and no difference was observed in the recipient's age, donor's age, cold ischemia time, time elapsed until plasmatic creatinine normalization, donor's plasmatic creatinine or urea, and mean arterial pressure. No differences were observed between the groups regarding frequency of infection episodes during ARF and frequency of death. In conclusion, renal allograft recipients presented a lower death rate and were less susceptible to sepsis. Cold ischemia time, age, and hemodynamic characteristics of the donor did not affect the development of oliguria.