Comparison of three early biomarkers for acute kidney injury after cardiac surgery under cardiopulmonary bypass

Low dimensional nanomaterials for treating acute kidney injury

Acute kidney injury (AKI) is one of the most common severe complications among hospitalized patients. In the absence of specific drugs to treat AKI, hemodialysis remains the primary clinical treatment for AKI patients. AKI treatment has received significant attention recently due to the excellent drug delivery capabilities of low-dimensional nanomaterials (LDNs) and their unique therapeutic effects. Diverse LDNs have been proposed to treat AKI, with promising results and the potential for future clinical application. This article aims to provide an overview of the pathogenesis of AKI and the recent advances in the treatment of AKI using different types of LDNs. In addition, it is intended to provide theoretical support for the design of LDNs and implications for AKI treatment.

Acute Kidney Injury following Cardiopulmonary Bypass: A Challenging Picture

Recent studies have recognized several risk factors for cardiopulmonary bypass- (CPB-) associated acute kidney injury (AKI). However, the lack of early biomarkers for AKI prevents practitioners from intervening in a timely manner. We reviewed the literature with the aim of improving our understanding of the risk factors for CPB-associated AKI, which may increase our ability to prevent or improve this condition. Some novel early biomarkers for AKI have been introduced. In particular, a combinational use of these biomarkers would be helpful to improve clinical outcomes. Furthermore, we discuss several interventions that are aimed at managing CPB-associated AKI, may increase the effect of renal replacement therapy (RRT), and may contribute to preventing CPB-associated AKI. Collectively, the conclusions of this paper are limited by the availability of clinical trial evidence and conflicting definitions of AKI. A guideline is urgently needed for CPB-associated AKI.

Daily Urinary Sodium Excretion Monitoring in Critical Care Setting: A Simple Method for an Early Detection of Acute Kidney Injury

Introduction:

Making an early diagnosis of acute kidney injury (AKI) is crucial. Classical biomarkers are not capable of early detection of AKI, but novel biomarkers that do have this capability are expensive and not universally available. This prospective study attempts to mitigate these limitations through the evaluation of daily urine analysis on patient admitted to a critical care unit in order to detect early AKI.

Methods:

Daily urinary indices were measured on every patient admitted to the intensive care unit (ICU) from the time of admission until his/her discharge from the ICU or death. This renal monitoring consisted of daily blood and spot morning urine samples in order to measure creatinine, urea, sodium, chloride and potassium in order to calculate the fractional excretion of sodium (FENa), chloride, urea and potassium. The data collected on these patients in the previous days was analyzed to determine whether or not there was a significant statistical difference in the urinary indices one day before the clinical diagnosis of AKI (day – 1) and 2 days before the diagnosis (day – 2). The statistical test applied was a single rank test, using as a limit of significance a value of P < 0.05.

Results:

Of the 203 patients included, 61 developed AKI. A statistical significant difference was documented only in the value of urinary sodium (UNa) and FENa between day-1 (one day before AKI clinical diagnosis) and day-2 (two days before AKI clinical diagnosis).

Conclusion:

Daily monitoring of UNa and FENa detected a significant change in their basal values 24 hours before clinical diagnosis of AKI was made.

Will urinary biomarkers provide a breakthrough in diagnosing cardiac surgery-associated AKI? - A systematic review

Introduction: Acute kidney injury following cardiac surgery is a dreaded complication contributing to early mortality. Diagnosing AKI using serum creatinine usually results in a delay. To combat this, certain kidney damage specific biomarkers were investigated to identify if they can serve as early predictors of cardiac surgery-associated AKI (CSA-AKI). This study systematically reviews three such biomarkers; NGAL, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein-7 (IGFBP7) to identify if they can serve as early predictors of CSA-AKI.Methods: Systematic search was carried out on literature reporting the diagnostic ability of the three biomarkers from databases in accordance with PRISMA guidelines.Results: We found 43 articles reporting urinary-NGAL levels (n = 34 in adults, n = 9 in children) and 10 studies reporting TIMP-2 and IGFBP7 levels among adults. Interestingly, NGAL showed high diagnostic value in predicting AKI in children (seven among nine studies with AUROC > 0.8). The cell cycle arrest biomarkers, namely TIMP-2 and IGFBP7, showed high diagnostic value in predicting AKI in adults (five among ten studies with AUROC > 0.8).Conclusion: In predicting CSA-AKI; the diagnostic value of NGAL is high in the paediatric population while the diagnostic value of TIMP-2 and IGFBP7 is high in adults.

Dynamic 2-deoxy-2[18F] fluoro-D-glucose PET/MRI in human renal allotransplant patients undergoing acute kidney injury

Patients after solid organ kidney transplantation (KTX) often suffer from acute kidney injury (AKI). Parameters as serum creatinine indicate a loss of kidney function, although no distinction of the cause and prognosis can be made. Imaging tools measuring kidney function have not been widely in clinical use. In this observational study we evaluated 2-deoxy-2[18F] fluoro-D-glucose (FDG) PET/MRI in thirteen patients after KTX with AKI as a functional assessment of the graft. Twenty-four healthy volunteers served as control. General kidney performance (GKP), initial flow (IF) and renal response function (RF) were calculated by standardized uptake values (SUV) and time activity curves (TAC). The GKP measured for the total kidney and medulla was significantly higher in healthy patients compared to patients after KTX (p = 0.0002 and p = 0.0004, respectively), but no difference was found for the GKP of the cortex (p = 0.59). The IF in KTX patients correlated with renal recovery, defined as change in serum creatinine 10 days after PET/MRI (r = 0.80, p = 0.001). With regard to the RF, a negative correlation for tubular damage was found (r = -0.74, p = 0.004). In conclusion, parameters obtained from FDG PET/MRI showed a possible predictive feature for renal recovery in KTX patients undergoing AKI.

Clinical and subclinical acute kidney injury in multidrug-resistant septic patients treated with colistimethate sodium: Incidence and clinical outcomes

AIM

Colistimethate sodium (CMS) has been postulated as the principal cause of high incidence of clinical acute kidney injury (AKI) in multidrug-resistance (MDR) septic patients with normal baseline serum creatinine (sCr) who were treated with CMS. This prospective observational study was conducted to examine the incidence and clinical outcomes of clinical and subclinical AKI in MDR septic patients receiving CMS.

METHODS

Forty-two MDR septic patients with normal sCr who required CMS were included. Clinical AKI was diagnosed by increased sCr levels according to the KDIGO2012 criteria while subclinical AKI was identified by elevated levels of urinary neutrophil gelatinase-associated lipocalin (uNGAL > 150 ng/mL) or urinary liver-type fatty-acid-binding protein (uL-FABP > 10.5 ng/mL).

RESULTS

Clinical AKI was noted in 47.6% of patients on day 5 and 38.1% on day 7 after initiating CMS. By using uL-FABP, subclinical AKI was observed in 45.2% and 54.8% on day 5 and 7, respectively. At baseline prior to CMS treatment, subclinical AKI was already present in 90%. The baseline uL-FABP was superior to the baseline uNGAL in early prediction of clinical AKI on day 5. The subclinical AKI patients had comparable worse outcomes as clinical AKI patients.

CONCLUSION

The incidence of subclinical AKI in MDR septic patients before CMS treatment was extremely high. The baseline uL-FABP provided the best predictive capacity of clinical AKI. The causes of clinical AKI might include the persistence of sepsis process, subclinical AKI and CMS nephrotoxicity. Proper management of subclinical AKI patients before CMS initiation should be concerned to prevent further renal damage and improve patient and renal outcomes.

Biomarkers of Acute Kidney Injury after Cardiac Surgery: A Narrative Review

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a major and serious complication in patients undergoing cardiac surgery and is independently associated with perioperative mortality and mortality. Therapeutic intervention aiming at reversing kidney dysfunction seems disappointing across multiple settings. Consequently, attention has shifted from treatment to prevention and early detection. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines have unified diagnostic standards mainly based on the serum creatinine (Scr) level or urine output, but neither marker is kidney specific. Efforts have been made to identify novel biomarkers with high sensitivity and specificity. The diagnostic capabilities of neutrophil gelatinase-associated lipocalin (NGAL) and G1 cell cycle arrest biomarker as biomarkers have been confirmed in a large number of clinical trials. The utility of biomarkers of cardiac function and inflammation has been validated in clinical studies. Aiming to offer valuable information for further research, we summarize the progress in defining current markers relevant to CSA-AKI in the last three years.

High levels of cell-free DNA accurately predict late acute kidney injury in patients after cardiac surgery

Use of cardiopulmonary bypass in cardiac surgery triggers systemic inflammation by neutrophil activation leading to neutrophil extracellular traps (NETs) release. Hence, nuclear DNA released by necrotic and apoptotic cells might contribute to an increase in circulating cell-free DNA (cfDNA). cfDNA/NETs might induce endothelial damage and organ dysfunction. This study focuses on the accuracy of cfDNA to predict acute kidney injury (AKI) after on-pump surgery. 58 cardiac patients undergoing on-pump surgery were prospectively enrolled. Blood samples were taken preoperatively, immediately after surgery, at day 1, 2, 3 and 5 from patients with (n = 21) or without (n = 37) postoperative AKI development. Levels of cfDNA, neutrophil gelatinase-associated lipocalin (NGAL) and creatinine in patients’ plasma were quantified. ROC curves were used to assess the predictive value of the biomarkers for AKI. Further baseline characteristics and perioperative variables were analyzed.cfDNA and NGAL levels highly increased in AKI patients and significant intergroup differences (vs. non-AKI) were found until day 3 and day 5 after surgery, respectively. cfDNA levels were significantly elevated in patients who developed late AKI (>24 hours), but not in those with AKI development during the first 24 hours (early AKI). NGAL and creatinine, which were highest in patients with early AKI, accurately predicted during the first 24 postoperative hours (early AKI). At day 3, at a threshold of 260.53 ng/ml cfDNA was the best predictor for AKI (AUC = 0.804) compared to NGAL (AUC = 0.699) and creatinine (AUC = 0.688). NGAL, but not cfDNA, was strongly associated with AKI stages and mortality. Monitoring of cfDNA levels from the first postoperative day might represent a valuable tool to predict late AKI after on-pump surgery.

Acute Kidney Injury after Cardiac Surgery: Risk Factors and Novel Biomarkers

Acute kidney injury (AKI) is a common and severe complication after cardiac surgery. Currently, a series of novel biomarkers have favored the assessment of AKI after cardiac surgery in addition to the conventional indicators. The biomartkers, such as urinary liver fatty acid binding protein (L-FABP), urinary neutrophil gelatinase-associated lipocalin (NGAL), serum L-FABP, heart-type FABP, kidney injury molecule 1 (KIM-1), and interleukin-18 were found to be significantly higher in patients who developed AKI after cardiac surgery than those who did not. Apart from urinary interleukin-18, the novel biomarkers have been recognized as reliable indicators for predicting the diagnosis, adverse outcome, and even mortality of AKI after cardiac surgery. The timing of the renal replacement therapy is a significant predictor relating to patients’ prognoses. In patients with AKI after cardiac surgery, renal replacement therapy should be performed as early as possible in order to achieve promising outcomes. In children, AKI after cardiac surgery can be managed with peritoneal dialysis. AKI after cardiac surgery has received extensive attention as it may increase early mortality and impact long-term survival of patients as well. The purpose of this article was to analyze the changes of the pertinent biomarkers, to explore the related risk factors leading to the occurrence of AKI after cardiac surgery, and to provide a basis for the clinical prevention and reduction of AKI.

Urine neutrophil gelatinase-associated lipocalin predicts outcome and renal failure in open and endovascular thoracic abdominal aortic aneurysm surgery

Urine neutrophil gelatinase–associated lipocalin (uNGAL) has been evaluated as a biomarker for AKI detection and adverse outcome in open and endovascular thoracoabdominal aortic aneurysm surgery. This observational, retrospective study included 52 patients. UNGAL was measured peri-operatively (48 h) and correlated with AKI requiring dialysis, tracheotomy and adverse outcome. Mean patients’ age was 64.5 years. A total of 26.9% (n = 14) developed AKI, and 21.1% (n = 11) required dialysis, tracheotomy rate was 19.2% (n = 10) and in-hospital mortality rate was 7.6% (n = 4). uNGAL levels were related to AKI requiring dialysis at ICU (p = 0.0002), need for tracheotomy at baseline and admission on ICU (p = 0.0222, p = 0.0028, respectively), as well as adverse discharge modality (p = 0.0051, p = 0.0048, respectively). Diagnostic quality was good for uNGAL levels at admission to ICU regarding AKI requiring dialysis (sensitivity: 81.8% [48.2–97.7]; specificity: 87.8% [73.8–95.9]; area under the curve (AUC): 0.874 [0.752–0.949]). The diagnostic quality of uNGAL was favorable for the prediction of tracheotomy (sensitivity: 70.0% [34.8–93.3]; specificity: 83.3% [68.6–93.0]; AUC: 0.807 [0.674–0.903]) and adverse discharge (sensitivity: 77.8% [40.0–97.2]; specificity: 83.7% [69.3–93.2]; AUC: 0.817 [0.685–0.910]). uNGAL may be valuable as an post-operative predictor of AKI and adverse outcome after open and endovascular TAAA repair.

Renal Angina Is a Sensitive, but Nonspecific Identifier of Postcardiac Surgery Acute Kidney Injury

OBJECTIVES

Acute kidney injury (AKI) is a common complication of cardiac surgery, and early detection is difficult. This study was performed to determine the sensitivity, specificity, positive predictive value, negative predictive value, and statistical performance of renal angina (RA) as an early predictor of AKI in an adult cardiac surgical patient population.

DESIGN

Retrospective, nonrandomized, observational study.

SETTING

A single, university-affiliated, quaternary medical center.

PARTICIPANTS

The study comprised 324 consecutive patients undergoing coronary artery bypass grafting or cardiac valvular surgery from February 1 through July 30, 2014.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred-seven patients at moderate or high risk of developing postoperative renal injury were identified, 82 of whom met criteria for RA. The occurrence of RA was found to have an 80.9% sensitivity and 30.8% specificity for the prediction of AKI using Acute Kidney Injury Network criteria and 89.3% sensitivity and 27.8% specificity when paired with the Risk, Injury, Failure, Loss, End Stage Renal Disease criteria. A receiver operating characteristic area under the curve analysis revealed a nonsignificant predictive ability of 55.8% (95% confidence interval 0.47-0.65) when RA was paired with Acute Kidney Injury Network criteria; however, the receiver operating characteristic area under the curve was significant when paired with Risk, Injury, Failure, Loss, End Stage Renal Disease criteria, with a predictive ability of 0.586 (0.509-0.662).

CONCLUSIONS

RA is a sensitive, but nonspecific, predictor of postcardiac surgery AKI, with clinical utility most suited as a screening tool.

Diagnosis of cardiac surgery-associated acute kidney injury from functional to damage biomarkers

PURPOSE OF REVIEW

Acute kidney injury (AKI) occurs in up to 30% after cardiac surgery and is associated with adverse outcome. Currently, cardiac surgery-associated acute kidney injury (CSA-AKI) is diagnosed by Kidney Disease: Improving Global Outcomes criteria based on creatinine and urine output. To detect and treat AKI earlier, various biomarkers have been evaluated. This review addresses the current position of the two damage biomarkers neutrophil gelatinase-associated lipocalin (NGAL) and [TIMP-2] [IGFBP7] in clinical practice.

RECENT FINDINGS

We present an updated review on the use of blood and urinary NGAL in CSA-AKI. NGAL is a good predictor, and performs better in children than adults. There is a large variation in predictive ability, possibly caused by diversity of AKI definitions used, different time of measurement of NGAL, and lack of specificity of NGAL assays.Similarly, there are conflicting data on the predictive ability of urinary [TIMP-2] [IGFBP7] for CSA-AKI.Recently, both for NGAL and for urinary [TIMP-2] [IGFBP7], a set of actions, based on pretest assessment of risk for CSA-AKI and biomarker test results, was developed. These scores should be evaluated in prospective trials.

SUMMARY

NGAL and urinary [TIMP-2] [IGFBP7], in combination with pretest assessment, are promising tools for early detection and treatment in CSA-AKI.

Epidemiology and outcome of acute kidney injury in children, a single center study

BACKGROUND

Information on the epidemiology of Acute Kidney Injury (AKI) in children is scarce. We performed a single center retrospective cohort study to analyze the incidence of AKI, the male/female ratio, the underlying etiology, and age at presentation. We also aimed to assess outcome measured by mortality, duration of PICU stay, and development of Chronic Kidney Disease (CKD).

METHODS

Records were searched for children presenting with or developing AKI between 1st January 2008 and 1st January 2015. AKI was classified according to the pediatric Rifle criteria while the cause of AKI was defined as the major underlying disease.

RESULTS

Of the 28,295 children admitted, 167 episodes of AKI were identified, equaling 5.9 cases per 1000 children. Patients classified as Failure at presentation according to pRifle criteria where significantly more likely to need dialysis (27/50, 54%) compared to those presenting with Injury (12/57, 21.1%) or Risk (6/60, 10 %). Diarrhea-associated Hemolytic Uremic Syndrome (D+HUS) was the most frequent cause (20.3 %) peaking during the summer months, followed by cardiac surgery (13.7%), medication-related nephrotoxicity (13.2%), and acute Glomerulonephritis (12%). The median age of children admitted with AKI was 6.1 years (range 0.1-17) and 50.8% of cases were male. Twenty five (15%) children died while 27 (16.1%) developed CKD.

CONCLUSIONS

Pediatric AKI poses a significant problem and strategies aimed at prevention, early detection, treatment, and adequate follow-up are needed. D+HUS is the most common underlying cause and effective surveillance of Enterohemorrhagic E. coli infections in association with additional measures is highly recommended.

Biomarkers of acute kidney injury: the pathway from discovery to clinical adoption

Acute kidney injury (AKI) is a common complication of critical illnesses and has a significant impact on outcomes, including mortality and morbidities. Unfortunately, apart from prophylactic measures, no effective treatment for this syndrome is known. Therefore, early recognition of AKI not only can provide better opportunities for preventive interventions, but also opens many gates for research and development of effective therapeutic options. Over the last few years, several new AKI biomarkers have been discovered and validated to improve early detection, differential diagnosis, and differentiation of patients into risk groups for progressive renal failure, need for renal replacement therapy (RRT), or death. These novel AKI biomarkers complement serum creatinine (SCr) and urine output, which are the standard diagnostic tools for AKI detection. In this article, we review the available literature on characteristics of promising AKI biomarkers that are currently the focus of preclinical and clinical investigations. These biomarkers include neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), liver-type fatty acid-binding protein, interleukin 18 (lL-18), insulin-like growth factor-binding protein 7, tissue inhibitor of metalloproteinase 2 (TIMP-2), calprotectin, urine angiotensinogen (AGT), and urine microRNA. We then describe the clinical performance of these biomarkers for diagnosis and prognostication. We also appraise each AKI biomarker's advantages and limitations as a tool for early AKI recognition and prediction of clinical outcomes after AKI. Finally, we review the current and future states of implementation of biomarkers in the clinical practice.