Acute renal failure: time for consensus

Perioperative Acute Renal Injury: Revisiting Pathophysiology

BACKGROUND

Acute renal dysfunction and subsequent acute renal failure after cardiac surgery are associated with high mortality and morbidity. Early therapeutic or preventive intervention is hampered by the lack of an early biomarker for acute renal injury. Recent studies showed that urinary neutrophil gelatinase-associated lipocalin (NGAL or lipocalin 2) is upregulated early (within 1 to 3 h) after murine renal injury and in pediatric acute renal dysfunction after cardiac surgery. The authors hypothesized that postoperative urinary NGAL concentrations are increased in adult patients developing acute renal dysfunction after cardiac surgery compared with patients without acute renal dysfunction.

METHODS

After institutional review board approval, 81 cardiac surgical patients were prospectively studied. Urine samples were collected immediately before incision and at various time intervals after surgery for NGAL analysis by quantitative immunoblotting. Acute renal dysfunction was defined as peak postoperative serum creatinine increase by 50% or greater compared with preoperative serum creatinine.

RESULTS

Sixteen of 81 patients (20%) developed postoperative acute renal dysfunction, and the mean urinary NGAL concentrations in patients who developed acute renal dysfunction were significantly higher early after surgery (after 1 h, mean ± SD, 4,195 ± 6,520 vs. 1,068 ± 2,129 ng/ml; P < 0.01) compared with patients who did not develop acute renal dysfunction. Mean urinary NGAL concentrations continued to increase and remained significantly higher at 3 and 18 h after cardiac surgery in patients with acute renal dysfunction. In contrast, urinary NGAL in patients without acute renal dysfunction decreased rapidly after cardiac surgery.

CONCLUSIONS

Patients developing postoperative acute renal dysfunction had significantly higher urinary NGAL concentrations early after cardiac surgery. Urinary NGAL may therefore be a useful early biomarker of acute renal dysfunction after cardiac surgery. These findings may facilitate the early detection of acute renal injury and potentially prevent progression to acute renal failure.

Evaluation of renal markers and liver enzymes in patients infected with the Chikungunya virus

Chikungunya virus (CHIKV) is an arbovirus (Togaviridae family, Alphavirus genus) that was first identified in 1953 in Tanzania. In 2014, the Asian and East/Central/South/African (ECSA) genotypes were identified in Brazil, although the genotype that spread the most in the following years across the Brazilian territory was the ECSA. The clinical symptoms associated with the infection caused by CHIKV include mainly fever, myalgia, headache, and arthralgia. In infections caused by other arboviruses (such as the ones caused by Dengue and West Nile viruses), changes in biochemical markers are often observed. This study aims to evaluate the biochemical markers profile of kidney and liver injury in acute patients infected with CHIKV. Two groups of correlations were found between the variables analyzed, namely, one between liver enzymes (r = 0.91), and another for kidney markers (r = 0.54-0.66). A significant elevation in the percentage of altered creatinine in CHIKV-infected patients was observed, followed by uric acid and AST. Altogether, in 8 different comparisons, it was possible to observe statistically significant differences between the levels of the markers when compared to the manifestation of symptoms (presence and absence). These noticeable changes in marker measurements could potentially be connected to the range of clinical symptoms seen in the disease.

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

Background

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

Methods

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

Results

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

Conclusion

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

Combination versus monotherapy as definitive treatment for Pseudomonas aeruginosa bacteraemia: a multicentre retrospective observational cohort study

BACKGROUND

Pseudomonas aeruginosa bacteraemia is a common and serious infection. No consensus exists regarding whether definitive combination therapy is superior to monotherapy. We aimed to evaluate the impact of combination therapy on mortality.

METHODS

This was a multicentre retrospective study (nine countries, 25 centres), including 1277 patients with P. aeruginosa bacteraemia during 2009-15. We evaluated the association between β-lactam plus aminoglycoside or quinolone combination therapy versus β-lactam monotherapy and mortality. The primary outcome was 30 day all-cause mortality. Univariate and multivariate Cox regression analyses were conducted, introducing combination as a time-dependent variable. Propensity score was conducted to adjust for confounding for choosing combination therapy over monotherapy.

RESULTS

Of 1119 patients included, 843 received definitive monotherapy and 276 received combination therapy (59% aminoglycoside and 41% quinolone). Mortality at 30 days was 16.9% (189/1119) and was similar between combination (45/276; 16.3%) and monotherapy (144/843; 17.1%) groups (P = 0.765). In multivariate Cox regression, combination therapy was not associated with reduced mortality (HR 0.98, 95% CI 0.64-1.53). No advantage in terms of clinical failure, microbiological failure or recurrent/persistent bacteraemia was demonstrated using combination therapy. Likewise, adverse events and resistance development were similar for the two regimens.

CONCLUSIONS

In this retrospective cohort, no mortality advantage was demonstrated using combination therapy over monotherapy for P. aeruginosa bacteraemia. Combination therapy did not improve clinical or microbiological failure rates, nor affect adverse events or resistance development. Our finding of no benefit with combination therapy needs confirmation in well-designed randomized controlled trials.

Use of Cell Cycle Arrest Biomarkers in Conjunction With Classical Markers of Acute Kidney Injury

Supplemental Digital Content is available in the text.

Decreased urine output and/or increased serum creatinine may herald the development of acute kidney injury or reflect normal physiology. In this secondary analysis of the Sapphire study, we examined biomarkers of cell cycle arrest in the settings of oliguria and/or azotemia to improve risk assessment when used with conventional indices in predicting severe acute kidney injury (Kidney Disease: Improving Global Outcomes 3 defined by the need for renal replacement therapy or changes in urine output, serum creatinine or both) or death.

Evaluating the risk of hyperkalaemia and acute kidney injury with cotrimoxazole: a retrospective observational study

OBJECTIVES

Increasing antimicrobial resistance has renewed interest in older, less used antimicrobials. Cotrimoxazole shows promise; however, hyperkalaemia and acute kidney injury (AKI) are potential complications. Identifying risk factors for and quantification of these events is required for safe use. This study aimed to evaluate predictors of cotrimoxazole-associated AKI and hyperkalaemia in a clinical setting.

METHODS

Patients prescribed cotrimoxazole were identified using electronic healthcare records over 3 years (1 April 2016 to 31 March 2019). Individual risk factors were recognized. Serum creatinine and potassium trends were analysed over the subsequent 21 days. AKI and patients with hyperkalaemia were classified using Kidney Disease Improving Global Outcomes (KDIGO) and laboratory criteria. Univariate and multiple logistic regression analyses were performed.

RESULTS

Among 214 patients prescribed cotrimoxazole, 42 (19.6%, 95% confidence interval (CI) 14.6-25.7) met AKI criteria and 33 (15.4%, 95% CI 11.0-21.1) developed hyperkalaemia. Low baseline estimated glomerular filtration rate (<60 mL/min/1.73 m², odds ratio (OR) 7.78, 95% CI 3.57-16.13, p < 0.0001) and cardiac disorders (OR 2.40, 95% CI 1.17-4.82, p 0.011) predicted AKI, while low baseline estimated glomerular filtration rate (<60 mL/min/1.73 m², OR 6.80, 95% CI 3.09-15.06, p < 0.0001) and higher baseline serum potassium (p 0.001) predicted hyperkalaemia. Low-dose cotrimoxazole (<1920 mg/d) was associated with lower AKI and hyperkalaemia risk (p 0.007 and 0.019 respectively). Early (within the first 2-4 days of therapy) serum creatinine changes predicted AKI (OR 3.65, 95% CI 1.73-7.41, p 0.001), and early serum potassium changes predicted hyperkalaemia (>0.6 mmol/L, OR 2.47, 95% CI 1.14-5.27, p 0.0236).

CONCLUSIONS

Cotrimoxazole-associated AKI and hyperkalaemia is frequent and dose dependent. Renal function, serum potassium and preexisting cardiac disorders should be evaluated before prescribing cotrimoxazole. Serum creatinine and potassium monitoring within first 2 to 4 days of treatment to identify susceptible patients is recommended, and the lowest effective dose ought to be prescribed.

Risk prediction for acute kidney injury in acute medical admissions in the UK

BACKGROUND

Acute Kidney Injury (AKI) is associated with adverse outcomes; therefore identifying patients who are at risk of developing AKI in hospital may lead to targeted prevention.

AIM

We undertook a UK-wide study in acute medical units (AMUs) to define those who develop hospital-acquired AKI (hAKI); to determine risk factors associated with hAKI and to assess the feasibility of developing a risk prediction score.

DESIGN

Prospective multi-centre cohort study across 72 AMUs in the UK.

METHODS

Data collected from all patients who presented over a 24-h period. Chronic dialysis, community-acquired AKI (cAKI) and those with fewer than two creatinine measurements were excluded. Primary outcome was the development of h-AKI.

RESULTS

Two thousand four hundred and fourty-six individuals were admitted to the seventy-two participating centres. Three hundred and eighty-four patients (16%) sustained AKI of whom two hundred and eighty-seven (75%) were cAKI and ninety-seven (25%) were hAKI. After exclusions, chronic kidney disease [Odds Ratio (OR) 3.08, 95% Confidence Interval (CI) 1.96-4.83], diuretic prescription (OR 2.33, 95% CI 1.5-3.65), a lower haemoglobin concentration and elevated serum bilirubin were independently associated with development of hAKI. Multi-variable model discrimination was only moderate (c-statistic 0.75).

CONCLUSIONS

AKI in AMUs is common and associated with worse outcomes, with the majority of cases community acquired. Only a small proportion of patients develop hAKI. Prognostic risk factor modelling demonstrated only moderate discrimination implying that widespread adoption of such an AKI clinical risk score across all AMU admissions is not currently justified. More targeted risk assessment or automated methods of calculating individual risk may be more appropriate alternatives.

Modification of sequential organ failure assessment score using acute kidney injury classification

PURPOSE

To assess the predictive validity of a modified Sequential Organ Failure Assessment (SOFA) score, of which the renal component was replaced with Kidney Disease Improving Global Outcomes (KDIGO) classification of Acute Kidney Injury (AKI).

MATERIALS AND METHODS

Using a prospective cohort study on AKI in Japan, we replaced the renal component of SOFA score with AKI stages according to the KDIGO criteria except that initiation of renal replacement therapy was assigned four points. We assessed the predictive validity of KDIGO-based SOFA score for hospital and ICU mortality by comparing the areas under the receiver operating characteristic curve (AUC) derived from logistic regression models with that of the original SOFA score.

RESULTS

2292 patients were registered. Overall hospital mortality was 11.6%, and ICU mortality was 5.1%. KDIGO-based SOFA score was moderately correlated with APACHE II score (rho = 0.476). The AUC for hospital and ICU mortality of KDIGO-based and the original SOFA score were 0.749 vs 0.745 (p = .393) and 0.790 vs 0.791 (p = .900).

CONCLUSIONS

The prognostic performance of KDIGO-based SOFA score was not superior but comparable to that of the original SOFA score.

The aftermath of acute kidney injury: a narrative review of long-term mortality and renal function

Acute kidney injury (AKI) is a frequent complication of hospitalization and is associated with an increased risk of chronic kidney disease (CKD), end-stage renal disease (ESRD), and mortality. While AKI is a known risk factor for short-term adverse outcomes, more recent data suggest that the risk of mortality and renal dysfunction extends far beyond hospital discharge. However, determining whether this risk applies to all patients who experience an episode of AKI is difficult. The magnitude of this risk seems highly dependent on the presence of comorbid conditions, including cardiovascular disease, hypertension, diabetes mellitus, preexisting CKD, and renal recovery. Furthermore, these comorbidities themselves lead to structural renal damage due to multiple pathophysiological changes, including glomeruloscleroses and tubulointerstitial fibrosis, which can lead to the loss of residual capacity, glomerular hyperfiltration, and continued deterioration of renal function. AKI seems to accelerate this deterioration and increase the risk of death, CDK, and ESRD in most vulnerable patients. Therefore, we strongly advocate adequate hemodynamic monitoring and follow-up in patients susceptible to renal dysfunction. Additionally, other potential renal stressors, including nephrotoxic medications and iodine-containing contrast fluids, should be avoided. Unfortunately, therapeutic interventions are not yet available. Additional research is warranted and should focus on the prevention of AKI, identification of therapeutic targets, and provision of adequate follow-up to those who survive an episode of AKI.

Effect and Safety of Meropenem-Vaborbactam versus Best-Available Therapy in Patients with Carbapenem-Resistant Enterobacteriaceae Infections: The TANGO II Randomized Clinical Trial

Introduction

Treatment options for carbapenem-resistant Enterobacteriaceae (CRE) infections are limited and CRE infections remain associated with high clinical failure and mortality rates, particularly in vulnerable patient populations. A Phase 3, multinational, open-label, randomized controlled trial (TANGO II) was conducted from 2014 to 2017 to evaluate the efficacy/safety of meropenem–vaborbactam monotherapy versus best available therapy (BAT) for CRE.

Methods

A total of 77 patients with confirmed/suspected CRE infection (bacteremia, hospital-acquired/ventilator-associated bacterial pneumonia, complicated intra-abdominal infection, complicated urinary tract infection/acute pyelonephritis) were randomized, and 47 with confirmed CRE infection formed the primary analysis population (microbiologic-CRE-modified intent-to-treat, mCRE-MITT). Eligible patients were randomized 2:1 to meropenem–vaborbactam (2 g/2 g over 3 h, q8h for 7–14 days) or BAT (mono/combination therapy with polymyxins, carbapenems, aminoglycosides, tigecycline; or ceftazidime-avibactam alone). Efficacy endpoints included clinical cure, Day-28 all-cause mortality, microbiologic cure, and overall success (clinical cure + microbiologic eradication). Safety endpoints included adverse events (AEs) and laboratory findings.

Results

Within the mCRE-MITT population, cure rates were 65.6% (21/32) and 33.3% (5/15) [95% confidence interval (CI) of difference, 3.3% to 61.3%; P = 0.03)] at End of Treatment and 59.4% (19/32) and 26.7% (4/15) (95% CI of difference, 4.6% to 60.8%; P = 0.02) at Test of Cure;.Day-28 all-cause mortality was 15.6% (5/32) and 33.3% (5/15) (95% CI of difference, − 44.7% to 9.3%) for meropenem–vaborbactam versus BAT, respectively. Treatment-related AEs and renal-related AEs were 24.0% (12/50) and 4.0% (2/50) for meropenem–vaborbactam versus 44.0% (11/25) and 24.0% (6/25) for BAT. Exploratory risk–benefit analyses of composite clinical failure or nephrotoxicity favored meropenem–vaborbactam versus BAT (31.3% [10/32] versus 80.0% [12/15]; 95% CI of difference, − 74.6% to − 22.9%; P < 0.001).

Conclusions

Monotherapy with meropenem–vaborbactam for CRE infection was associated with increased clinical cure, decreased mortality, and reduced nephrotoxicity compared with BAT.

Clinical Trials Registration

NCT02168946.

Funding

The Medicines Company.

Electronic supplementary material

The online version of this article (10.1007/s40121-018-0214-1) contains supplementary material, which is available to authorized users.

Prevention of Acute Renal Failure: Role of Vaso-Active Drugs, Mannitol and Diuretics

Evidence exists that acute renal failure (ARF) independently increases mortality risk in critically-ill patients. Therefore prevention of ARF seems of paramount importance. Preservation of renal blood flow and (sufficient) perfusion pressure favourably influences the prevention of renal function deterioration in the critically-ill septic patient. The first step to achieve this is infusion of fluids, either crystalloids or colloids, with the aim of optimal fluid resuscitation. Although “optimal fluid resuscitation” is poorly defined, in clinical practice it can be considered as the point where a certain preload is obtained, after which no further increase of cardiac output is observed with further fluid infusion. Vasoactive drugs can be added to this regimen in case of insufficient restoration of flow and especially perfusion pressure. The addition of norepinephrine can be of value if high doses of dopamine fail to restore perfusion pressure. No evidence exists that low-dose dopamine prevents renal failure and, therefore, dopamine should not be given for this indication. The use of diuretic agents can be harmful, as indicated by observational and cohort studies. Although mannitol flushes out intratubular casts and increases tubular flow, which is favorable in myoglobinuria or hemoglobinuria, so far no well designed clinical studies have demonstrated its efficacy in ARF. In conclusion, there is currently no convincing evidence for any benefit from diuretic agents and/or (low dose) dopamine in the prevention of ARF. High quality intenisve care and avoidance of harm is, therefore, the current standard of the prevention of ARF.

Systematic review of prognostic prediction models for acute kidney injury (AKI) in general hospital populations

OBJECTIVE

Critically appraise prediction models for hospital-acquired acute kidney injury (HA-AKI) in general populations.

DESIGN

Systematic review.

DATA SOURCES

Medline, Embase and Web of Science until November 2016.

ELIGIBILITY

Studies describing development of a multivariable model for predicting HA-AKI in non-specialised adult hospital populations. Published guidance followed for data extraction reporting and appraisal.

RESULTS

14 046 references were screened. Of 53 HA-AKI prediction models, 11 met inclusion criteria (general medicine and/or surgery populations, 474 478 patient episodes) and five externally validated. The most common predictors were age (n=9 models), diabetes (5), admission serum creatinine (SCr) (5), chronic kidney disease (CKD) (4), drugs (diuretics (4) and/or ACE inhibitors/angiotensin-receptor blockers (3)), bicarbonate and heart failure (4 models each). Heterogeneity was identified for outcome definition. Deficiencies in reporting included handling of predictors, missing data and sample size. Admission SCr was frequently taken to represent baseline renal function. Most models were considered at high risk of bias. Area under the receiver operating characteristic curves to predict HA-AKI ranged 0.71-0.80 in derivation (reported in 8/11 studies), 0.66-0.80 for internal validation studies (n=7) and 0.65-0.71 in five external validations. For calibration, the Hosmer-Lemeshow test or a calibration plot was provided in 4/11 derivations, 3/11 internal and 3/5 external validations. A minority of the models allow easy bedside calculation and potential electronic automation. No impact analysis studies were found.

CONCLUSIONS

AKI prediction models may help address shortcomings in risk assessment; however, in general hospital populations, few have external validation. Similar predictors reflect an elderly demographic with chronic comorbidities. Reporting deficiencies mirrors prediction research more broadly, with handling of SCr (baseline function and use as a predictor) a concern. Future research should focus on validation, exploration of electronic linkage and impact analysis. The latter could combine a prediction model with AKI alerting to address prevention and early recognition of evolving AKI.

Risk factors for mortality in postoperative peritonitis in critically ill patients

AIM

To identify the risk factors for mortality in intensive care patients with postoperative peritonitis (POP).

METHODS

This was a retrospective analysis using a prospective database that includes all patients hospitalized in a surgical intensive care unit for POP from September 2006 to August 2011. The data collected included demographics, comorbidities, postoperative severity parameters, bacteriological findings, adequacy of antimicrobial therapy and surgical treatments. Adequate source control was defined based on a midline laparotomy, infection source control and intraoperative peritoneal lavage. The number of reoperations needed was also recorded.

RESULTS

A total of 201 patients were included. The overall mortality rate was 31%. Three independent risk factors for mortality were identified: The Simplified Acute Physiological II Score (OR = 1.03; 95%CI: 1.02-1.05, P < 0.001), postoperative medical complications (OR = 6.02; 95%CI: 1.95-18.55, P < 0.001) and the number of reoperations (OR = 2.45; 95%CI: 1.16-5.17, P = 0.015). Surgery was considered as optimal in 69% of the cases, but without any significant effect on mortality.

CONCLUSION

The results from the large cohort in this study emphasize the role of the initial postoperative severity parameters in the prognosis of POP. No predefined criteria for optimal surgery were significantly associated with increased mortality, although the number of reoperations appeared as an independent risk factor of mortality.

Evaluation of Nephroprotective Efficacy of Hypoxic Preconditioning in Patients Undergoing Coronary Artery Bypass Surgery

BACKGROUND

Nonpulsatile blood flow plays an important role in the pathogenesis of renal dysfunction in patients with extracorporeal circulation. In our opinion, hypoxic preconditioning (HP) can be used to protect kidneys from postsurgical dysfunction. The aim of this study was to evaluate nephroprotective efficacy of HP in myocardial revascularization with extracorporeal circulation.

METHODS

The randomized, controlled trial was performed in 63 patients undergoing coronary artery bypass grafting (CABG). Thirty-three patients were subjected to HP during CABG; 30 patients were included in the comparison group. All patients underwent dynamic renal scintigraphy with (99m)Тc-diethylenetriaminepentaacetic acid and were subjected to measuring the concentration of lipocalin in blood serum before and after CABG.

RESULTS

After CABG, the mean values of the total glomerular filtration rate (GFR) and GFR for each kidney significantly decreased only in patients of the comparison group. Significant increases in the concentration of serum neutrophil gelatinase-associated lipocalin occurred 5 h after surgery both in the group with HP (70.65 ± 46.71 to 127.58 ± 98.46 ng/ml) and in the comparison group (65.01 ± 38.64 to 171.65 ± 89.91 ng/ml). At the same time, the mean difference values between pre- and postoperative lipocalin levels were 56.94 ± 51.75 ng/ml in the study group and 106.64 ± 51.27 ng/ml in the comparison group; these differences were highly statistically significant (р = 0.004).

CONCLUSION

The results of our study showed that (i) HP exerts nephroprotection in patients undergoing on-pump CABG, and (ii) determination of the lipocalin-2 level can be used for early diagnosis of acute kidney injury in cardiac surgery patients.

The Impact of Deep Versus Moderate Hypothermia on Postoperative Kidney Function After Elective Aortic Hemiarch Repair

BACKGROUND

There remains concern that moderate hypothermic circulatory arrest (MHCA) with antegrade cerebral perfusion (ACP) may provide suboptimal distal organ protection compared with deep hypothermic circulatory arrest (DHCA) with retrograde cerebral perfusion (RCP). We compared postoperative acute kidney injury (AKI) in in patients who underwent elective hemiarch repair with either DHCA/RCP or MHCA/ACP.

METHODS

This was a retrospective review of all patients undergoing elective aortic hemiarch reconstruction for aneurysmal disease between 2009 and 2014. Patients were stratified according to the use of DHCA/RCP versus MHCA/ACP. The primary outcome was the occurrence of AKI at 48 hours, as defined by the Risk, Injury, Failure, Loss, End-Stage (RIFLE ) criteria. A multivariable logistic regression identified risk factors for AKI.

RESULTS

One hundred eighteen patients who underwent ACP and 471 patients who underwent RCP were included. The mean lowest temperature was 26.4°C in patients who underwent MHCA/ACP and 17.5°C in patients who underwent DHCA/RCP. Baseline demographics were similar except that patients who underwent DHCA/RCP were more likely to have peripheral arterial disease or bicuspid aortic valves. Cardiopulmonary bypass and aortic cross-clamp times were shorter in the MHCA/ACP group. AKI occurred in 19 (16.2%) patients who underwent MHCA/ACP and 67 (14.3%) patients who underwent DHCA/RCP. Four (0.8%) patients who underwent DHCA/RCP required postoperative dialysis. In-hospital mortality tended to increase with increasing RIFLE classification (RIFLE class-0 (No AKI) = 0.41%; Risk = 1.35%, and Injury = 10.0%; p = 0.09). On multivariable analysis, the lowest temperature and cerebral perfusion strategy were not significant predictors of AKI. Lower baseline glomerular filtration rate (GFR), lower preoperative ejection fraction, and longer cardiopulmonary bypass (CPB) time were independently associated with higher AKI.

CONCLUSIONS

We applied the sensitive RIFLE criteria to examine AKI in patients undergoing elective aortic hemiarch replacement for aneurysmal disease. Baseline renal dysfunction, lower ejection fraction, and longer CPB time are independent predictors of AKI. Compared with DHCA/RCP, our data suggest that an MHCA/ACP cerebral protection strategy does not appear to be associated with worse postoperative renal outcomes.

The Complex Relationship of Extracorporeal Membrane Oxygenation and Acute Kidney Injury: Causation or Association?

Extracorporeal membrane oxygenation (ECMO) is a modified cardiopulmonary bypass (CPB) circuit capable of providing prolonged cardiorespiratory support. Recent advancement in ECMO technology has resulted in increased utilisation and clinical application. It can be used as a bridge-to-recovery, bridge-to-bridge, bridge-to-transplant, or bridge-to-decision. ECMO can restitute physiology in critically ill patients, which may minimise the risk of progressive multiorgan dysfunction. Alternatively, iatrogenic complications of ECMO clearly contribute to worse outcomes. These factors affect the risk : benefit ratio of ECMO which ultimately influence commencement/timing of ECMO. The complex interplay of pre-ECMO, ECMO, and post-ECMO pathophysiological processes are responsible for the substantial increased incidence of ECMO-associated acute kidney injury (EAKI). The development of EAKI significantly contributes to morbidity and mortality; however, there is a lack of evidence defining a potential benefit or causative link between ECMO and AKI. This area warrants investigation as further research will delineate the mechanisms involved and subsequent strategies to minimise the risk of EAKI. This review summarizes the current literature of ECMO and AKI, considers the possible benefits and risks of ECMO on renal function, outlines the related pathophysiology, highlights relevant investigative tools, and ultimately suggests an approach for future research into this under investigated area of critical care.

Defining acute kidney injury in dengue viral infection by conventional and novel classification systems (AKIN and RIFLE): a comparative analysis

BACKGROUND

Several criteria have been used to stratify acute kidney injury (AKI) in dengue infection and have resulted in variations in its incidence as well as clinic-laboratory characteristics. The current study was aimed to compare three commonly used criteria of AKI among patients with dengue.

METHODS

667 patients with dengue were defined and staged according to the conventional definition (CD), the Acute Kidney Injury Network (AKIN) and the Risk, Injury, Failure, Loss of function, End stage renal disease (RIFLE) criteria. Appropriate statistical methods were used to compare these three criteria.

RESULTS

The incidence of AKI during dengue infection was 14.2% by AKIN criteria, 12.6% by RIFLE criteria and 4.2% by CD. AKIN and RIFLE criteria were comparable while AKIN-I identified 11 more patients with AKI than RIFLE-R (76.8% vs. 73.8%, p=0.023). CD was found to be less sensitive than AKIN and RIFLE due to stratification of only severe AKI cases with serum creatinine ≥176.8 µmol/L. Overall mortality was 1.2% and severe stages of AKI were associated with increased mortality (p<0.001). AKIN criteria identified seven risk factors, RIFLE identified six and CD identified three risk factors. Old age, severe dengue and the use of nephrotoxic drugs were found to be independent predictors identified by all criteria while hypertension was only identified by AKIN.

CONCLUSIONS

The incidence of AKI in dengue infection, the risk factors for its development and clinico-laboratory characteristics vary significantly according to the diagnostic criteria used. In our analysis, AKIN and RIFLE were comparable to each other and superior to CD with regard to early diagnosis and sensitivity.

Implementation of continuous renal replacement therapy with regional citrate anticoagulation on a surgical and trauma intensive care unit: impact on clinical and economic aspects-an observational study

BACKGROUND

Regional citrate anticoagulation (RCA) is being increasingly used during continuous renal replacement therapy (CRRT) in intensive care units as an alternative to systemic heparin anticoagulation. However, due to its availability in a variety of solutions and dialysis systems, RCA is still considered a complex intervention, possibly leading to confusion and pitfalls in everyday practice. We therefore tested retrospectively if the introduction of RCA as a new anticoagulation strategy for CRRT was feasible and had not negatively impacted efficacy, safety, metabolic stability, filter lifetime, and cost-effectiveness compared to well-established systemic heparin.

METHODS

This observational, retrospective study was performed on a non-cardiac surgical and trauma intensive care unit (ICU) in a university hospital. All charts of patients receiving one of the CRRT techniques from May 2006 to April 2010 were reviewed. The first 60 consecutive patients receiving CRRT with regional citrate anticoagulation after its implementation in February 2008 (continuous veno-venous haemodialysis, Multifiltrate® with integrated CiCa® system, AV 1000 S® filter, n = 60) were included in the study. The last 50 consecutive patients with systemic heparin anticoagulation therapy (continuous veno-venous haemodiafiltration, PRISMAFLEX®, AN69® filter, n = 50), treated immediately before the introduction of RCA, were used as a historic control group.

RESULTS

Both treatment modalities were effective in terms of uraemia control. Patients in the citrate group presented with significantly higher pH levels, lower ionized calcium levels, and higher sodium levels compared with the heparin treated group, however, without notable adverse clinical events. Interestingly, mean circuit lifetime was significantly longer in the citrate group (48.6 ± 24.2 h vs. 18.8 ± 13.5 h; p < 0.0001). Both treatment modalities were cost-effective.

CONCLUSIONS

Our results suggest that the implementation of regional citrate anticoagulation was safe and effective. Due to the retrospective design of the study and inherent limitations therein concerning several baseline parameters, i.e. different filters, modes of dialysis, and flow parameters not having been standardized, we were unable to draw a causative effect relationship. Nonetheless, our results warrant further study.

Incidence, Predictors, and Impact on Hospital Mortality of Amphotericin B Nephrotoxicity Defined Using Newer Acute Kidney Injury Diagnostic Criteria

Studies on amphotericin B (AmB) nephrotoxicity use diverse definitions of acute kidney injury (AKI). Here, we used the new Kidney Disease Improving Global Outcome (KDIGO) system to describe the incidence, predictors, and impact of AmB-induced AKI on hospital mortality in 162 patients treated with AmB (120 with deoxycholate preparation and 42 with liposomal preparation). KDIGO stage 1 requires an absolute increase of ≥0.3 mg/dl or ≥1.5× over baseline serum creatinine (SCr), while stage 2 requires ≥2×, and stage 3 requires ≥3×. A binary KDIGO definition (KDIGObin) corresponds to stage ≥1. For comparison, we included two definitions of AKI traditionally utilized in nephrotoxicity studies: ≥0.5 mg/dl (NT0.5) and ≥2× (NT2×) increase in baseline SCr. The overall incidence of AmB-induced AKI by KDIGObin was 58.6% (stage 1, 30.9%; stage 2, 18.5%; stage 3, 9.3%). Predictors of AKI by KDIGObin were older age and use of furosemide and angiotensin-converting enzyme inhibitor (ACE-I). Traditional criteria detected lower incidences of AKI, at 45.1% (NT0.5) and 27.8% (NT2×). Predictors of AKI by traditional criteria were older age and use of vancomycin (NT0.5) and use of vancomycin and vasopressors (NT2×). KDIGObin detected AKI 2 days earlier than the most sensitive traditional criterion. However, only traditional criteria were associated with intensive care unit (ICU) admission, mechanical ventilation, and mortality. In conclusion, the increase in sensitivity of KDIGObin is accompanied by a loss of specificity and ability to predict outcomes. Prospective studies are required to weigh the potential gain from early AKI detection against the potential loss from undue changes in management in patients with subtle elevations in SCr.

The interface between monitoring and physiology at the bedside

Hemodynamic instability as a clinical state represents either a perfusion failure with clinical manifestations of circulatory shock or heart failure or 1 or more out-of-threshold hemodynamic monitoring values, which may not necessarily be pathologic. Different types of causes of circulatory shock require different types of treatment modalities, making these distinctions important. Diagnostic approaches or therapies based on data derived from hemodynamic monitoring assume that specific patterns of derangements reflect specific disease processes, which respond to appropriate interventions. Hemodynamic monitoring at the bedside improves patient outcomes when used to make treatment decisions at the right time for patients experiencing hemodynamic instability.

Acute renal failure according to the RIFLE and AKIN criteria: a multicenter study

OBJECTIVE

To determine the incidence of acute renal failure (ARF) in critically ill patients using the RIFLE and AKIN criteria.

DESIGN

A prospective, multicenter observational study with a duration of one year from February 2010 was carried out. RIFLE and AKIN were employed using the urinary (UC) and creatinine criteria (CC) jointly and separately.

SCOPE

Nine polyvalent Critical Care Units (CCUs) in Argentina.

PATIENTS

A total of 627 critical patients over 18 years of age were admitted to the CCU for more than 48h.

EXCLUSION CRITERIA

inability to quantify diuresis, surgical instrumentation of the urinary tract, and need for renal support therapy (RST).

VARIABLES OF INTEREST

Calculated hourly diuresis (CHD) was used to apply the UC.

RESULTS

The incidence of ARF was 69.4% and 51.8% according to RIFLE and AKIN, respectively. UC detected ARF in 59.5% of cases, while CC identified ARF in 34.7% (RIFLE) and 25.3% (AKIN). The mortality rate was 40.9% and 44.6% according to RIFLE and AKIN respectively, was significantly higher than in patients without ARF, and increased with disease severity (Data processing: Excel, SQL and SPSS. Levene test, comparison of means with Student t and chi-squared, with 95% confidence interval).

CONCLUSIONS

RIFLE identified more cases of ARF. UC proved more effective than CC. The presence of ARF and severity levels were correlated to mortality but not to days of stay in the CCU. Implementation of the unified CHD was useful for implementing UC and achieving comparable results.

[Perioperative acute kidney injury and failure]

Perioperative period is very likely to lead to acute renal failure because of anesthesia (general or perimedullary) and/or surgery which can cause acute kidney injury. Characterization of acute renal failure is based on serum creatinine level which is imprecise during and following surgery. Studies are based on various definitions of acute renal failure with different thresholds which skewed their comparisons. The RIFLE classification (risk, injury, failure, loss, end stage kidney disease) allows clinicians to distinguish in a similar manner between different stages of acute kidney injury rather than using a unique definition of acute renal failure. Acute renal failure during the perioperative period can mainly be explained by iatrogenic, hemodynamic or surgical causes and can result in an increased morbi-mortality. Prevention of this complication requires hemodynamic optimization (venous return, cardiac output, vascular resistance), discontinuation of nephrotoxic drugs but also knowledge of the different steps of the surgery to avoid further degradation of renal perfusion. Diuretics do not prevent acute renal failure and may even push it forward especially during the perioperative period when venous retourn is already reduced. Edema or weight gain following surgery are not correlated with the vascular compartment volume, much less with renal perfusion. Treatment of perioperative acute renal failure is similar to other acute renal failure. Renal replacement therapy must be mastered to prevent any additional risk of hemodynamic instability or hydro-electrolytic imbalance.

Comparison of kidney disease: improving global outcomes and acute kidney injury network criteria for assessing patients in intensive care units

BACKGROUND

The Kidney Disease: Improving Global Outcomes (KDIGO) group proposed to adopt the 48-h time window for the 0.3 mg/dL rise in serum creatinine (sCr) proposed by the Acute Kidney Injury Network (AKIN) group as a modification to the original risk, injury, failure, loss, and end-stage renal disease criteria, keeping the 7-day window for the 50 % increase in sCr from baseline. The present study evaluates the prevalence of acute kidney injury (AKI) and the accuracy of predicting mortality based on the KDIGO and AKIN criteria.

PATIENTS AND METHODS

We retrospectively studied a cohort of 2579 patients admitted to the intensive care unit of Nagoya University Hospital between 2005 and 2009.

RESULTS

The total AKI prevalence was higher according to the KDIGO than to the AKIN criteria (38.4 versus 29.5 %). In-hospital mortality rates were higher among 238 patients classified as non-AKI by the AKIN but AKI by the KDIGO criteria than among those classified as non-AKI by both criteria (7.1 versus 2.7 %). Survival curves generated using KDIGO significantly differed among all stages, but not between AKIN stages I and II. Multivariate analysis showed that KDIGO criteria were better in a statistical model than the AKIN criteria according to the Akaike information criterion. Harrell's C statistic was greater for the KDIGO than for the AKIN criteria.

CONCLUSIONS

The KDIGO criteria have improved sensitivity without compromising specificity for AKI and might predict mortality at least as well as the AKIN criteria.

Comparison of diagnostic criteria for acute kidney injury in cardiac surgery

Background

There is considerable controversy regarding the diagnosis of Acute Kidney Injury (AKI), and there are over 30 different definitions.

Objective

To evaluate the incidence and risk factors for the development of AKI following cardiac surgery according to the RIFLE, AKIN and KDIGO criteria, and compare the prognostic power of these criteria.

Methods

Cross-sectional study that included 321 consecutive patients (median age 62 [53-71] years; 140 men) undergoing cardiac surgery between June 2011 and January 2012. The patients were followed for up to 30 days, for a composite outcome (mortality, need for dialysis and extended hospitalization).

Results

The incidence of AKI ranged from 15% - 51%, accordingly to the diagnostic criterion adopted. While age was associated with risk of AKI in the three criteria, there were variations in the remaining risk factors. During follow-up, 89 patients developed the outcome and all criteria were associated with increased risk in the univariate Cox analysis and after adjustment for age, gender, diabetes, and type of surgery. However, after further adjustment for extracorporeal circulation and the presence of low cardiac output, only AKI diagnosed by the KDIGO criterion maintained this significant association (HR= 1.89 [95% CI: 1.18 - 3.06]).

Conclusion

The incidence and risk factors for AKI after cardiac surgery vary significantly according to the diagnostic criteria used. In our analysis, the KDIGO criterion was superior to AKIN and RIFLE with regard its prognostic power.

Estimating kidney function in the critically ill patients

Glomerular filtration rate (GFR) is an accepted measure for assessment of kidney function. For the critically ill patient, creatinine clearance is the method of reference for the estimation of the GFR, although this is often not measured but estimated by equations (i.e., Cockroft-Gault or MDRD) not well suited for the critically ill patient. Functional evaluation of the kidney rests in serum creatinine (Crs) that is subjected to multiple external factors, especially relevant overhydration and loss of muscle mass. The laboratory method used introduces variations in Crs, an important fact considering that small increases in Crs have serious repercussion on the prognosis of patients. Efforts directed to stratify the risk of acute kidney injury (AKI) have crystallized in the RIFLE or AKIN systems, based in sequential changes in Crs or urine flow. These systems have provided a common definition of AKI and, due to their sensitivity, have meant a considerable advantage for the clinical practice but, on the other side, have introduced an uncertainty in clinical research because of potentially overestimating AKI incidence. Another significant drawback is the unavoidable period of time needed before a patient is classified, and this is perhaps the problem to be overcome in the near future.

Survival in Critically Ill Patients with Acute Kidney Injury Treated with Early Hemodiafiltration

Purpose

Early renal replacement therapy (RRT) initiation should theoretically influence many physiological disorders related to acute kidney injury (AKI). Currently, there is no consensus about RRT timing in intensive care unit (ICU) patients.

Methods

We performed a retrospective analysis of all critically ill patients who received RRT in our ICU during a 3 year-period. Our goal was to identify mortality risk factors and if RRT initiation timing had an impact on survival. RRT timing was calculated from the moment the patient was classified as having acute kidney injury in the RIFLE classification.

Results

A hundred and ten patients received RRT. We identified four independent mortality risk factors: need for mechanical ventilation (OR = 12.82 (1.305 - 125.868, p = 0.0286); RRT initiation timing >16 h (OR = 5.66 (1.954 - 16.351), p = 0.0014); urine output on admission <500 ml/day (OR = 4.52 (1.666 - 12.251), p = 0.003); and SAPS II on admission >70 (OR = 3.45 (1.216 - 9.815), p = 0.02). The RRT initiation <16 h and RRT initiation >16 h groups presented the same baseline characteristics, except for more severe gravity scores and kidney failure in the early RRT group.

Conclusions

Early RRT in ICU patients with acute kidney injury or failure was associated with increased survival.

Predictors of renal replacement therapy in acute kidney injury

Backgrounds

Criteria that may guide early renal replacement therapy (RRT) initiation in patients with acute kidney injury (AKI) currently do not exist.

Methods

In 120 consecutive patients with AKI, clinical and laboratory data were analyzed on admittance. The prognostic power of those parameters which were significantly different between the two groups was analyzed by receiver operator characteristic curves and by leave-1-out cross validation.

Results

Six parameters (urine albumin, plasma creatinine, blood urea nitrogen, daily urine output, fluid balance and plasma sodium) were combined in a logistic regression model that estimates the probability that a particular patient will need RRT. Additionally, a second model without daily urine output was established. Both models yielded a higher accuracy (89 and 88% correct classification rate, respectively) than the best single parameter, cystatin C (correct classification rate 74%).

Conclusions

The combined models may help to better predict the necessity of RRT using clinical and routine laboratory data in patients with AKI.

A critical appraisal of the accuracy of the RIFLE and AKIN classifications in defining "acute kidney insufficiency" in critically ill patients

PURPOSE

The lack of a consensus definition for acute kidney injury (AKI) has led to a great deal of discrepancies and confusion in the literature in this field. Thus, the RIFLE (Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function and End-stage renal disease) and Acute Kidney Injury Network (AKIN) classifications were developed by multidisciplinary collaborative groups and were validated by experts in an international consensus conference in 2007 under an umbrella "acute kidney insufficiency" definition.

METHODS

Search in the MEDLINE and PUBMED databases for relevant literature from January 2000 to June 2011 was performed to assess the accuracy of the novel consensus definitions for AKI.

CONCLUSIONS

Both systems are based on serum creatinine level and urine output criteria and are staged in 3 severity levels. A major difference between these 2 classifications is that smaller and more rapid changes in serum creatinine are considered in the AKIN stage 1. Each AKI classification has demonstrated its ability to stratify patients according to their AKI severity and to predict outcomes. No classification system has been shown to be superior over the others. Their application in clinical studies would benefit from standardization and the new Kidney Disease Improving Global Outcomes definition of AKI was recently proposed to achieve this aim. Because these classifications do not allow earlier AKI diagnosis and do not optimize the timing of RRT initiation, they remain of moderate utility from the patient's point of view.

Acute kidney injury increases mortality after lung transplantation

BACKGROUND

Acute kidney injury requiring renal replacement therapy (RRT) is associated with increased mortality after cardiac surgery. Studies examining the impact of RRT after lung transplantation (LTx) are limited. We evaluated risk factors and outcomes associated with RRT after LTx.

METHODS

We retrospectively reviewed all LTx recipients in the United Network for Organ Sharing database. Preoperative renal function was stratified by glomerular filtration rate (GFR) as determined by the Modification of Diet in Renal Disease formula (strata: ≥90, 60 to 90, and <60 mL · min(-1) · 1.73 m(-2)). Primary outcomes were 30-day, 1-year, and 5-year survival and need for post-LTx RRT. Risk adjusted multivariable Cox proportional hazards regression examined mortality. A multivariable logistic regression model evaluated risk factors for RRT.

RESULTS

From 2001 to 2011, 12,108 patients underwent LTx. After LTx, 655 patients (5.51%) required RRT. Patients requiring post-LTx RRT had decreased survival at 30 days (96.7% versus 76.0%, p < 0.001), 1 year (85.5% versus 35.8%, p < 0.001), and 5 years (56.4% versus 20.0%, p < 0.001). These differences persisted on multivariable analysis at 30 days (hazard ratio [HR] 7.98 [6.16 to 10.33], p < 0.001), 1 year (HR 7.93 [6.84 to 9.19], p < 0.001), and 5 years (HR 5.39 [4.75 to 6.11], p < 0.001). Preoperative kidney function was an important predictor of post-LTx RRT for a GFR of 60 to 90 (odds ratio 1.42 [1.16 to 1.75], p = 0.001) and a GFR less than 60 (odds ratio 2.68 [2.07 to 3.46], p < 0.001]. High center volume was protective.

CONCLUSIONS

In the largest study to evaluate acute kidney injury after LTx, the incidence of RRT is 5.51%. The need for post-LTx RRT dramatically increases both short- and long-term mortality. Several variables, including preoperative renal function, are predictors of post-LTx RRT and could be used to identify transplant candidates at risk for acute kidney injury.

Patient influx and trauma types in a front-line hospital and a secondary referral hospital after the Wenchuan earthquake: a retrospectively comparative study

PURPOSE

To better understand the differences of patient influx and types of trauma between front-line and referral hospitals after the Wenchuan earthquake, so as to improve the efficiency of injury management.

METHODS

A retrospective and comparative study was performed in Deyang People's Hospital (a front-line hospital) and West China Hospital (a secondary referral hospital).

RESULTS

A total of 1,106 patients were admitted to the front-line hospital, and 1,775 to the secondary referral hospital. The patient flow peaked within 24 h after the quake, and decreased dramatically thereafter in the front-line hospital, while it peaked 2 days after the disaster in the referral one. Extremities were the most frequent location of all identified injuries (48.4% in the front-line hospital and 49.5% in the second-line hospital). Head and trunk injuries were more frequent in the front-line hospital than the referral hospital. Most of the deaths in the front-line hospital occurred within 24 h (6/8), whilst most in the referral hospital died more than 7 days (29/30) after the earthquake. While the total mortality in the front-line hospital was less than that in the referral hospital (0.7 vs 1.7%), the critical mortality in the former was higher (22.8 vs 9.4%).

CONCLUSIONS

There were dramatically different features in terms of quake-related patient influx and types of injury between the epicenter and less-affected hospitals.

Total-to-ionized calcium ratio predicts mortality in continuous renal replacement therapy with citrate anticoagulation in critically ill patients

INTRODUCTION

Regional citrate anticoagulation is safe, feasible and increasingly used in critically ill patients on continuous renal replacement therapy (CRRT). However, in patients with hepatic or multi-organ dysfunction, citrate accumulation may lead to an imbalance of calcium homeostasis. The study aimed at evaluating the incidence and prognostic relevance of an increased total to ionized calcium ratio (T/I Ca(2+) ratio) and its association to hepatic dysfunction.

METHODS

We performed a prospective observational study on n = 208 critically ill patients with acute kidney injury (AKI) and necessity for CRRT with regional citrate anticoagulation (CRRT-citrate) between September 2009 and September 2011. Critical illness was estimated by Simplified Acute Physiology Score II; hepatic function was measured with indocyanine green plasma disappearance rate. After achieving a steady state of calcium homeostasis patients were classified into tertiles according to the T/I Ca(2+) ratio (<2.0 versus 2.0 - 2.39 versus ≥ 2.4).

RESULTS

The T/I Ca(2+) ratio was determined as an independent predictor for 28-day mortality in critically ill patients with AKI on CRRT-citrate confirmed by receiver operating characteristics and multivariate analysis (Area under the curve 0.94 ± 0.02; p<0.001). A T/I Ca(2+) ratio ≥ 2.4 independently predicted a 33.5-fold (p<0.001) increase in 28-day mortality-rate. There was a significant correlation between the T/I Ca(2+) ratio and the hepatic clearance (p<0.001) and the severity of critical illness (p<0.001). The efficacy and safety of citrate anticoagulation, determined by blood urea nitrogen, mean filter patency and bleeding episodes, were not significantly different between the tertiles.

CONCLUSIONS

In patients on CRRT-citrate T/I Ca(2+) ratio is closely related to the clinical outcome and emerged as an independent predictor of 28-day mortality. Larger studies are required to define the cut-off and predictive value for the T/I Ca(2+) ratio. This ratio is associated with hepatic and/or multi-organ dysfunction and therefore an important therapeutic target.

Acute renal failure following lung transplantation: risk factors, mortality, and long-term consequences

OBJECTIVE

Acute renal failure (ARF) frequently complicates lung transplantation. This study determined the prevalence, predictive factors, and consequences of ARF on long-term renal function and survival.

METHODS

One hundred and seventy-four lung transplantation recipients were divided into two groups based on the presence or absence of ARF defined as a 50% decrease in creatinine clearance from baseline (group I: 67 patients with ARF; group II: 107 patients without ARF). Multivariate analysis compared pre-operative, operative, and post-operative risk factors to assess predictive factors. Renal function over time was assessed by two-way repeated measures analysis of variance (ANOVA).

RESULTS

ARF developed in 67 (39%) of patients. Multivariate analysis identified aprotinin (OR 2.20 (1.11; 4.36), p=0.02) and double lung transplantation (OR 2.61 (1.32; 5.15), p=0.006) as risk factors for post-operative renal failure. At 5 years following transplant, creatinine clearance was similar between the two groups (group I CrCl: 73 ml s(-1); group II CrCl: 53 ml s(-1); p=0.54). Survival at 5 years was the same in the two groups. Multivariate analysis associated age at the time of transplantation (HR 1.030 (1.004; 1.057), p=0.02) and intensive care unit (ICU) length of stay (HR 1.029 (1.008; 1.051), p=0.007) with decreased survival.

CONCLUSIONS

The use of aprotinin and double lung transplantation are associated with ARF following lung transplantation. Age at the time of transplantation and a longer intensive care stay predict decreased survival. ARF after lung transplantation is not predictive of late renal dysfunction or decreased long-term survival.

Acute kidney injury network criteria as a predictor of hospital mortality in cirrhotic patients with ascites

BACKGROUND

Acute kidney injury (AKI) is frequent in cirrhotic patients but its best definition is unclear. Recently, the Acute Kidney Injury Network (AKIN) proposed criteria to define AKI. The aims of this study were to apply AKIN criteria to cirrhotic patients with ascites and to evaluate its association to hospital mortality.

STUDY

In this retrospective study, cirrhotic patients with ascites admitted to a university hospital in Brazil between November 2003 and December 2007 were included. AKIN criteria were applied in the first 48 hours of hospitalization, considering 2 values of creatinine in this period. Association of AKI at admission and hospital mortality was analyzed.

RESULTS

Of the 198 patients in the study, 91 (46%) presented AKI at hospital admission. Overall hospital mortality was 40.4%. Patients without AKI had a hospital mortality rate of 29.9%, whereas the same rate for patients with this complication was 52.7% (odds ratio=2.6; 95% confidence interval, 1.5-4.7; P=0.001). In a logistic regression analysis, 4 variables were independently associated to hospital mortality: infection, hepatic encephalopathy, Child score, and AKI. A receiver operating characteristic curve analysis revealed that the variation in creatinine proposed by AKIN had the best combination of sensitivity and specificity in relation to hospital mortality.

CONCLUSIONS

In cirrhotic patients with ascites, prevalence of AKI at hospital admission is high. Patients with renal dysfunction defined by AKIN have significant higher hospital mortality. AKIN criteria are useful in cirrhotic patients with ascites, as it identifies earlier patients with worse prognosis.

A systematic review of RIFLE criteria in children, and its application and association with measures of mortality and morbidity

The RIFLE criteria were developed to improve consistency in the assessment of acute kidney injury. The high face validity, collaborative development method, and validation against mortality have supported the widespread adoption of the RIFLE to evaluate adult patients; however, its inconsistent application in adult studies is associated with significant effects on the estimated incidence of acute kidney injury. As the RIFLE criteria are now being used to determine acute kidney injury in children, we conducted a systematic review to describe its application and assess associations between the RIFLE and measures of mortality and morbidity in pediatric patients. In 12 studies we found wide variation in the application of the RIFLE, including the range of assessed RIFLE categories, omission of urine output criteria, varying definitions of baseline renal function, and methods for handling missing baseline measurements. Limited and conflicting associations between the RIFLE and mortality, length of stay, illness severity, and measures of kidney function were found. Thus, although the RIFLE was developed to improve the consistency of defining acute kidney injury, there are still major discrepancies in its use in pediatric patients that may undermine its potential utility as a standardized measure of acute kidney injury in children.

Outcome of critically ill patients with acute kidney injury using the Acute Kidney Injury Network criteria

OBJECTIVE

Acute kidney injury affects 5% to 7% of all hospitalized patients with a much higher incidence in the critically ill. The Acute Kidney Injury Network proposed a definition in which serum creatinine rises (>0.3 mg/dL) and/or oliguria (<0.5 mL/kg/hr) for a period of 6 hrs are used to detect acute kidney injury. Accurate urine output measurements as well as serum creatinine values from our database were used to detect patients with acute kidney injury and calculate their corresponding mortality risk and length of stay.

DESIGN

Retrospective cohort study.

SETTING

Seven intensive care units at a large, academic, tertiary medical center.

PATIENTS

Adult patients without evidence of end-stage renal disease with more than two creatinine measurements and at least a 6-hr urine output recording who were admitted to the intensive care unit between 2001 and 2007.

INTERVENTIONS

Medical records of all the patients were reviewed. Demographic information, laboratory results, charted data, discharge diagnoses, physiological data, and patient outcomes were extracted from the Multiparameter Intelligent Monitoring in Intensive Care II database using a SQL query.

MEASUREMENTS AND MAIN RESULTS

From 19,677 adult patient records, 14,524 patients met the inclusion criteria. Fifty-seven percent developed acute kidney injury during their intensive care unit stay. Inhospital mortality rates were: 13.9%, 16.4%, 33.8% for acute kidney injury 1, 2, and 3, respectively, compared with only 6.2% in patients without acute kidney injury (p < .0001). After adjusting for multiple covariates, acute kidney injury was associated with increased hospital mortality (odds ratio 1.4 and 1.3 for acute kidney injury 1 and acute kidney injury 2 and 2.5 for acute kidney injury 3; p < .0001). Using multivariate logistic regression, we found that in patients who developed acute kidney injury, urine output alone was a better mortality predictor than creatinine alone or the combination of both.

CONCLUSIONS

More than 50% of our critically ill patients developed some stage of acute kidney injury resulting in a stagewise increased mortality risk. However, the mortality risk associated with acute kidney injury stages 1 and 2 does not differ significantly. In light of these findings, re-evaluation of the Acute Kidney Injury Network staging criteria should be considered.

Established markers of renal and hepatic failure are not appropriate to predict mortality in the acute stage before extracorporeal life support implantation

OBJECTIVES

End-organ function, especially of the kidney and liver, actual inflammation and acid-base balance affect the outcome in extracorporeal life support (ECLS) patients. However, the often unexpected necessity of ECLS implies that information on patients is scarce. Even established global scores are not always useful in the rapid decision process for ECLS. Therefore, we evaluated laboratory parameters for kidney or liver function and for inflammation and acid-base balance with regard to outcome.

METHODS

The retrospective analysis includes 69 consecutive adult patients with veno-arterial ECLS. Laboratory markers for function of kidney (creatinine, urea) and liver (total bilirubin in plasma, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase) as well as for inflammation (C-reactive protein, leucocyte counts) and acid-base balance (pH, lactate) were acquired within 24 h before ECLS implantation.

RESULTS

A total of 38 patients (55%) could be weaned or bridged. Bridged patients were switched to ventricular assist devices, n=10, or total artificial hearts, n=2, and one patient underwent heart transplantation. Overall, 26 ECLS patients (38%) survived for >4 weeks. Thirty-one patients (45%) died on ECLS. About three out of four patients presented with impaired renal or hepatic performance, approximately two-thirds with signs of increased inflammatory state, and more than a half with deranged acid-base balance. Neither signs of hepatic or renal failure nor of inflammation or impaired acid-base balance allowed a prediction of survival in these patients. The outcome did also not depend on indication for ECLS implantation. However, there was a significant correlation between the patients' age and mortality (P=0.006).

CONCLUSIONS

Our data indicate that renal and hepatic insufficiency, increased inflammatory state and deranged acid-base balance as determined by pre-operative laboratory data are not associated with poor outcome of ECLS. Further, survival is not related to indications for ECLS. In a number of patients, ECLS allows for successful bridging to other treatment options.

Are enterococci playing a role in postoperative peritonitis in critically ill patients?

This prospective non-interventional study is aimed at evaluating the role of enterococci in the postoperative course of postoperative peritonitis (POP) and the predictive factors for isolating Enterococcus spp. All adult patients, hospitalized in intensive care, who had POP between September 2006 and February 2010 were analysed. The patients' baseline clinical characteristics and microbiological and surgical characteristics of the first episode of POP were recorded. The rates of surgical and non-surgical complications and mortality were studied. A total of 139 patients were analysed and Enterococcus spp. were recovered in 61 patients (43%). The presence of enterococci was associated with significantly more intra-abdominal abscesses (26% vs 12%, p=0.025), but did not affect the rate of reoperation or mortality. Antibiotic use before reoperation was the only independent predictive factor for isolating enterococci (OR=2.19, CI95%: 1.02-4.70, p<0.043). Although mortality was not affected by the presence of Enterococcus spp., a higher rate of intra-abdominal abscess was found, suggesting that enterococci play a significant role in postoperative peritonitis, but the need to treat them remains to be determined. Previous antibiotic use before reoperation was a key factor in predicting the subsequent recovery of enterococci.

AKI in the ICU: definition, epidemiology, risk stratification, and outcomes

Acute kidney injury (AKI) has emerged as a major public health problem that affects millions of patients worldwide and leads to decreased survival and increased progression of underlying chronic kidney disease (CKD). Recent consensus criteria for definition and classification of AKI have provided more consistent estimates of AKI epidemiology. Patients, in particular those in the ICU, are dying of AKI and not just simply with AKI. Even small changes in serum creatinine concentrations are associated with a substantial increase in the risk of death. AKI is not a single disease but rather a syndrome comprising multiple clinical conditions. Outcomes from AKI depend on the underlying disease, the severity and duration of renal impairment, and the patient's renal baseline condition. The development of AKI is the consequence of complex interactions between the actual insult and subsequent activation of inflammation and coagulation. Contrary to the conventional view, recent experimental and clinical data argue against renal ischemia-reperfusion as a sine qua non condition for the development of AKI. Loss of renal function can occur without histological signs of tubular damage or even necrosis. The detrimental effects of AKI are not limited to classical well-known symptoms such as fluid overload and electrolyte abnormalities. AKI can also lead to problems that are not readily appreciated at the bedside and can extend well beyond the ICU stay, including progression of CKD and impaired innate immunity. Experimental and small observational studies provide evidence that AKI impairs (innate) immunity and is associated with higher infection rates.

Acute kidney injury: not just acute renal failure anymore?

Until recently, no uniform standard existed for diagnosing and classifying acute renal failure. To clarify diagnosis, the Acute Dialysis Quality Initiative group stated its consensus on the need for a clear definition and classification system of renal dysfunction with measurable criteria. Today the term acute kidney injury has replaced the term acute renal failure, with an understanding that such injury is a common clinical problem in critically ill patients and typically is predictive of an increase in morbidity and mortality. A classification system, known as RIFLE (risk of injury, injury, failure, loss of function, and end-stage renal failure), includes specific goals for preventing acute kidney injury: adequate hydration, maintenance of renal perfusion, limiting exposure to nephrotoxins, drug protective strategies, and the use of renal replacement therapies that reduce renal injury.

Severe acute kidney injury according to the RIFLE (risk, injury, failure, loss, end stage) criteria affects mortality in lung transplantation

BACKGROUND

The RIFLE criteria (risk, injury, failure, loss, end stage) are new consensus definitions for acute kidney injury (AKI) associated with increased mortality; however, they have not been applied in lung transplantation (LTx). Using the RIFLE criteria, we examined the effect of AKI on outcomes and cost in LTx.

METHODS

We retrospectively reviewed all LTx patients at our institution since the lung allocation score (LAS) system was initiated (May 2005-August 2010). Using the Modification of Diet in Renal Disease formula, we assigned appropriate RIFLE class (R, I, F) comparing baseline creatinine to peak levels in the first 7 days after LTx. Generalized linear models assessed the effect of AKI on in-hospital and 1-year mortality. Hospital charges were used to examine the financial effect of AKI.

RESULTS

During the study, 106 LTx were performed. Excluding patients bridged to LTx with extracorporeal membrane oxygenation, 84 (86%) lived 1 year. Median LAS was 37.1 (interquartile range, 34.1-45.2). RIFLE status was I or F in 39 (36.7%), and 14 (13.2%) required renal replacement therapy (RRT). After adjusting for LAS, RIFLE-F had an increased relative rate (RR) of in-hospital mortality (RR, 4.76, 95% confidence interval [CI], 1.65-13.7, p = 0.004) and 1-year mortality (RR, 3.17, 95% CI 1.55-6.49, p = 0.002). RIFLE-R and I were not associated with higher in-hospital or 1-year mortality. Post-operative RRT was associated with increased in-hospital (RR, 28.2; 95% CI, 6.18-128.1; p < 0.001) and 1-year mortality (RR, 4.97; 95% CI, 1.54-16.0; p < 0.001). AKI patients had higher median hospital charges of $168,146 vs $143,551 for no AKI (p = 0.02).

CONCLUSIONS

This study shows high rates of AKI using the new RIFLE criteria in LTx. RIFLE-F is associated with higher in-hospital and 1-year mortality. Less severe degrees of AKI are not associated with increased mortality. The financial burden associated with AKI is significant.

Challenges of defining acute kidney injury

BACKGROUND

Until recently, there was a lack of a uniform definition for acute kidney injury (AKI). The 'acute renal injury/acute renal failure syndrome/severe acute renal failure syndrome' criteria, the Risk - Injury - Failure - Loss of kidney function - End stage renal disease (RIFLE) criteria and the Acute Kidney Injury Network (AKIN) classification were the most recent proposals.

AIM

To compare the performance of the different AKI definitions.

DESIGN AND METHODS

Application of the three most recent AKI definitions to 41 972 critically ill ICU patients and comparison of their performance.

RESULTS

Incidence and outcome of AKI varied depending on the criteria. The RIFLE and AKIN classification led to similar total incidences of AKI (35.9 vs. 35.4%) but different incidences and outcomes of the individual AKI stages. Multivariate analysis showed that the different stages of AKI were independently associated with mortality. The worst stage of AKI was associated with an increased odds ratio for mortality of 1.59-2.27. Non-surgical admission, maximum number of associated failed organ systems, emergency surgery and mechanical ventilation were consistently associated with the highest risk of hospital mortality. The proposed AKI definitions differ in the cut-off values of serum creatinine, the suggested time frame, the approach towards patients with missing baseline values and the method of classifying patients on renal replacement therapy. All classifications can miss patients with definite AKI.

CONCLUSION

The three most recent definitions of AKI confirmed a correlation between severity of AKI and outcome but have limitations and the potential to miss patients with definite AKI. These limitations need to be considered when using the criteria in clinical practice.