Postoperative biomarkers predict acute kidney injury and poor outcomes after pediatric cardiac surgery

The need for disruptive innovation in acute kidney injury

Acute kidney injury (AKI) is a threatening medical condition associated with poor outcomes at different settings. The development of standardized diagnostic criteria and new biomarkers addressed significant clinical impacts of AKI and the need for an early AKI detection, respectively. There have been some breakthroughs in understanding the pathogenesis of AKI through basic research; however, treatments against AKI aside from renal replacement therapy (RRT) have not shown adequate successful results. Biomarkers that could identify good responders to certain treatment are expected to facilitate translation of basic research findings. Most patients with severe AKI treated with RRT died due to multiple-organ failure, not renal dysfunction. Hence, it is essential to identify other organ dysfunctions induced by AKI as organ crosstalk. Also, a multidisciplinary approach of critical care nephrology is needed to evaluate a complex organ crosstalk in AKI. For disruptive innovation for AKI, we further explore these new aspects of AKI, which previously were considered outside the scope of nephrology.

Extracardiac Complications in Intensive Care Units after Surgical Repair for Congenital Heart Disease: Imaging Review with a Focus on Ultrasound and Radiography

Pediatric patients show various extracardiac complications after cardiovascular surgery, and radiography and ultrasound are routinely performed in the intensive care unit to detect and evaluate these complications. This review presents images of these complications, sonographic approach, and timing of occurrence that are categorized based on their extracardiac locations and include complications pertaining to the central nervous system, mediastinum, thorax and lung parenchyma, diaphragm, liver and biliary system, and kidney along with pleural effusion and iatrogenic complications. This pictorial review will make it easier for medical doctors in intensive care units to identify and manage various extracardiac complications in pediatric patients after cardiovascular surgery.

Patterns of Urinary Neutrophil Gelatinase-Associated Lipocalin and Acute Kidney Injury in Neonates Receiving Cardiopulmonary Bypass

Elevated urinary neutrophil gelatinase-associated lipocalin (uNGAL) predicts acute kidney injury (AKI) in children following cardiopulmonary bypass (CPB) during cardiac surgery, but little is known about uNGAL’s predictive ability in neonates in this setting. We sought to determine the relationship between AKI and post-CPB uNGAL in neonates in the first 72 post-operative hours. Methods: Urine samples for uNGAL analysis were collected at preoperative baseline and serially post-operatively from 76 neonates undergoing CPB. Mixed-effects regression models and logistic models assessed associations between uNGAL and AKI (controlling for sex, gestational age, CPB time, surgical complexity, and age at surgery). Receiver-operator curves were applied to define optimal uNGAL cut-off values for AKI diagnosis. Results: Between 0 and 4 h post-operatively, uNGAL values did not differ between neonates with and without AKI. After 4 h until 16 h post-operatively, significant time-wise separation occurred between uNGAL values of neonates with AKI and those without AKI. Odds ratios at each time point significantly exceeded unity, peaking at 10 h post-operatively (3.48 (1.58, 8.71)). Between 4 and 16 h post-operatively, uNGAL discriminated AKI from no-AKI, with a sensitivity of 0.63 (0.49, 0.75) and a specificity of 0.68 (0.62, 0.74) at a cut-off value of 100 ng/mL. Conclusion: After 4 h until 16 h post-operatively, elevated uNGAL is associated with AKI in neonates receiving CPB during cardiac surgery; however, this relationship is more complex than in older children.

Remote Ischemic Preconditioning and Contrast-Induced Acute Kidney Injury in Patients Undergoing Elective Percutaneous Coronary Intervention: A Randomized Clinical Trial

Background

Contrast-induced acute kidney injury (CI-AKI) is a common cause of hospital-acquired AKI and a serious complication of percutaneous coronary intervention.

Objective

The aim of the present study was to assess whether remote ischemic preconditioning (RIPC) reduces the incidence of CI-AKI.

Methods

We conducted a prospective, randomized, sham-controlled clinical study. The study included 101 patients admitted to the Intensive Cardiac Therapy Clinic of Medical University of Lodz for elective percutaneous coronary intervention. The participants were randomly assigned in a 1:1 ratio to either a control group (n = 51) or an RIPC group (n = 50). In the latter, RIPC was achieved before percutaneous coronary intervention by 4 cycles of 5-minute inflation of a cuff on the left upper arm to 200 mm Hg followed by 5-minute deflation. In the control group, a deflated cuff was placed on the left arm for 40 minutes. Serum creatinine concentration was measured to check for the presence of CI-AKI within 48 to 72 hours of percutaneous coronary intervention. Serum neutrophil gelatinase-associated lipocalin level was also measured within 3 hours.

Results

CI-AKI occurred in 2 patients from the RIPC group (4%) and 3 patients from the control group (5.9%), but the difference was not significant (P = 0.98). The patients who developed CI-AKI also demonstrated increased serum neutrophil gelatinase-associated lipocalin concentrations (the area under the receiver operator characteristic curve = 0.97; 95% CI, 0.938–1.00; P < 0.00) and the optimal cutoff point value was 118.9 ng/mL.

Conclusions

The use of RIPC before elective percutaneous coronary intervention was not found to prevent CI-AKI. ClinicalTrials.gov identifier: NCT03761368. (Curr Ther Res Clin Exp. 2020; 81:XXX–XXX)

Tubular injury and cell-cycle arrest biomarkers to predict acute kidney injury in noncritically ill children receiving aminoglycosides

Aim: NGAL, IL-18, KIM-1 as well as urinary TIMP2 and IGFBP7 and their mathematical product (TIMP2*IGFBP7) were evaluated for detecting pediatric aminoglycoside acute kidney injury (AG-AKI). Methods: In a prospective study, noncritically ill children received aminoglycosides (AG) ≥3 days. The area under the curve (AUC) for biomarkers to detect AKI was calculated by a) days before AKI onset; b) treatment days. Results: There were 113 AG episodes (68% febrile neutropenia). The AKI group had a higher proportion with febrile neutropenia. The AKI group had significantly lower NGAL 3 days before AKI, as patients with febrile neutropenia had a lower NGAL during AG treatment (p < 0.05). NGAL, IL-18 and TIMP2*IGFBP7 had AUC ≥0.73 at 3, 2 and 2 days before AKI onset. Conclusion: NGAL, IL-18 and TIMP2*IGFBP7 were modest early biomarkers of AG-AKI. Febrile neutropenia was associated with lower NGAL.

The Many Faces of Matrix Metalloproteinase-7 in Kidney Diseases

Matrix metalloproteinase-7 (MMP-7) is a secreted zinc-dependent endopeptidase that is implicated in regulating kidney homeostasis and diseases. MMP-7 is produced as an inactive zymogen, and proteolytic cleavage is required for its activation. MMP-7 is barely expressed in normal adult kidney but upregulated in acute kidney injury (AKI) and chronic kidney disease (CKD). The expression of MMP-7 is transcriptionally regulated by Wnt/β-catenin and other cues. As a secreted protein, MMP-7 is present and increased in the urine of patients, and its levels serve as a noninvasive biomarker for predicting AKI prognosis and monitoring CKD progression. Apart from degrading components of the extracellular matrix, MMP-7 also cleaves a wide range of substrates, such as E-cadherin, Fas ligand, and nephrin. As such, it plays an essential role in regulating many cellular processes, such as cell proliferation, apoptosis, epithelial-mesenchymal transition, and podocyte injury. The function of MMP-7 in kidney diseases is complex and context-dependent. It protects against AKI by priming tubular cells for survival and regeneration but promotes kidney fibrosis and CKD progression. MMP-7 also impairs podocyte integrity and induces proteinuria. In this review, we summarized recent advances in our understanding of the regulation, role, and mechanisms of MMP-7 in the pathogenesis of kidney diseases. We also discussed the potential of MMP-7 as a biomarker and therapeutic target in a clinical setting.

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.

Novel biomarkers of acute kidney injury in children: an update on recent findings

PURPOSE OF REVIEW

The clinical diagnosis of acute kidney injury (AKI) relies largely on changes in serum creatinine; a delayed biomarker. Research in children has been focused on developing novel AKI biomarkers, which can improve the prediction, early detection and diagnosis of kidney injury, as well as our understanding of AKI pathophysiology. In this review, we describe recently published studies on urine or blood biomarkers of AKI. The mechanistic relevance of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1, interleukin (IL)-18, liver-type fatty acid binding protein, tissue inhibitor of metalloproteinase (TIMP)-2/insulin-like growth factor-binding protein (IGFBP)-7, uromodulin, as well as other inflammatory biomarkers are discussed in the context of AKI pathophysiology, as well as their performance predicting or diagnosing AKI.

RECENT FINDINGS

Biomarkers of tubular injury, cell cycle arrest and inflammation are presented in this review. NGAL continues to be the most frequently studied biomarker and continues to have good performance in a variety of clinical settings, most notably after cardiopulmonary bypass. We also found promising results with less studied biomarkers for the prediction of AKI in children, including TIMP2, IGFBP7, uromodulin, tumor necrosis factor-α and IL-8.

SUMMARY

Identifying new AKI biomarkers is a priority in pediatric nephrology research because of the morbidity associated with AKI, as well as the lack of therapies for AKI. Recent research suggests that novel AKI biomarkers have the potential to predict the development of AKI and diagnose AKI earlier than changes in serum creatinine. The diverse causes of AKI, the different settings where patients develop AKI and the changing biomarker reference ranges throughout childhood remain challenges in biomarker development.

Biomarkers of Acute and Chronic Kidney Disease

The current unidimensional paradigm of kidney disease detection is incompatible with the complexity and heterogeneity of renal pathology. The diagnosis of kidney disease has largely focused on glomerular filtration, while assessment of kidney tubular health has notably been absent. Following insult, the kidney tubular cells undergo a cascade of cellular responses that result in the production and accumulation of low-molecular-weight proteins in the urine and systemic circulation. Modern advancements in molecular analysis and proteomics have allowed the identification and quantification of these proteins as biomarkers for assessing and characterizing kidney diseases. In this review, we highlight promising biomarkers of kidney tubular health that have strong underpinnings in the pathophysiology of kidney disease. These biomarkers have been applied to various specific clinical settings from the spectrum of acute to chronic kidney diseases, demonstrating the potential to improve patient care.

Current Status of Novel Biomarkers for the Diagnosis of Acute Kidney Injury: A Historical Perspective

Acute kidney injury (AKI) is a common and serious medical condition associated with significant increases in morbidity, mortality, and cost of care. Because of the high incidence and poor outcomes associated with AKI, there has been significant interest in the development of new therapies for the prevention and treatment of the disease. A lack of efficacy in drug trials led to the concern that AKI was not being diagnosed early enough for an effective intervention and that a rise in serum creatinine itself is not a sensitive-enough marker. Researchers have been searching for novel biomarkers that can not only assess a decline in kidney function but also demonstrate structural damage to the kidney and at time points earlier than increases in serum creatinine measurements allow. Over the past 10 years, there have been 3300 new publications and hundreds of new biomarkers investigated, yet concern still remains regarding AKI biomarker performance. The AKI biomarkers are yet to be widely utilized in clinical practice, leading some to question whether AKI biomarkers will ever reach their initial promise. However, we believe that biomarkers are an important part of current and future AKI research and clinical management. In this review, we compare the historical contexts of acute myocardial ischemia and AKI biomarker development to illustrate the progress that has been made within AKI biomarker research in a relatively short period of time and also to point out key differences between the disease processes that have been barriers to widespread AKI biomarker adoption. Finally, we discuss potential paths by which biomarkers can lead to appropriate AKI treatment responses that lower morbidity and mortality.

Acute Kidney Injury in Children after Hematopoietic Cell Transplantation Is Associated with Elevated Urine CXCL10 and CXCL9

Acute kidney injury (AKI) is nearly universally associated with worse outcomes, especially among children after hematopoietic stem cell transplant (HCT). Our objective was to examine urinary immune biomarkers of AKI after HCT to provide insights into novel mechanisms of kidney injury in this population. Studying patients undergoing allogeneic HCT provides a unique opportunity to examine immune markers of AKI because the risk of AKI is high and the immune system newly develops after transplant. Children (>2 years old) and young adults undergoing their first allogeneic HCT and enrolled in a prospective, observational cohort study at 2 large children's hospitals had urine collected pre-HCT and monthly for the first 4 months after HCT. Urine samples at each monthly time point were assayed for 8 immune-related biomarkers. AKI was defined as a 1.5-fold increase in the monthly serum creatinine value, which was recorded ±1 day from when the research urine sample was obtained, as compared with the pre-HCT baseline. Generalized estimating equation regression analysis evaluated the association between the monthly repeated measures (urinary biomarkers and AKI). A total of 176 patients were included from 2 pediatric centers. Thirty-six patients from 1 center were analyzed as a discovery cohort and the remaining 140 patients from the second center were analyzed as a validation cohort. AKI rates were 18% to 35% depending on the monthly time point after HCT. Urine CXCL10 and CXCL9 concentrations were significantly higher among children who developed AKI compared with children who did not (P < .01) in both cohorts. In order to gain a better understanding of the cellular source for these biomarkers in the urine, we also analyzed in vitro expression of CXCL10 and CXCL9 in kidney cell lines after stimulation with interferon-γ and interferon-α. HEK293-epithelial kidney cells demonstrated interferon-induced expression of CXCL10 and CXCL9, suggesting a potential mechanism driving the key finding. CXCL10 and CXCL9 are associated with AKI after HCT and are therefore promising biomarkers to guide improved diagnostic and treatment strategies for AKI in this high-risk population.

Kidney Biomarkers of Injury and Repair as Predictors of Contrast-Associated AKI: A Substudy of the PRESERVE Trial

RATIONALE & OBJECTIVE

The PRESERVE trial used a 2 × 2 factorial design to compare intravenous saline solution with intravenous sodium bicarbonate solution and oral N-acetylcysteine with placebo for the prevention of 90-day major adverse kidney events and death (MAKE-D) and contrast-associated acute kidney injury (CA-AKI) among patients with chronic kidney disease undergoing angiography. In this ancillary study, we evaluated the predictive capacities of preangiography injury and repair proteins in urine and plasma for MAKE-D, CA-AKI, and their impact on trial design.

STUDY DESIGN

Longitudinal analysis.

SETTING & PARTICIPANTS

A subset of participants from the PRESERVE trial.

EXPOSURES

Injury (KIM-1, NGAL, and IL-18) and repair (MCP-1, UMOD, and YKL-40) proteins in urine and plasma 1 to 2 hours preangiography.

OUTCOMES

MAKE-D and CA-AKI.

ANALYTICAL APPROACH

We analyzed the associations of preangiography biomarkers with MAKE-D and with CA-AKI. We evaluated whether the biomarker levels could enrich the MAKE-D event rate and improve future clinical trial efficiency through an online biomarker prognostic enrichment tool available at prognosticenrichment.com.

RESULTS

We measured plasma biomarkers in 916 participants and urine biomarkers in 797 participants. After adjusting for urinary albumin-creatinine ratio and baseline estimated glomerular filtration rate, preangiography levels of 4 plasma (KIM-1, NGAL, UMOD, and YKL-40) and 3 urine (NGAL, IL-18, and YKL-40) biomarkers were associated with MAKE-D. Only plasma KIM-1 level was significantly associated with CA-AKI after adjustment. Biomarker levels provided modest discriminatory capacity for MAKE-D. Screening patients using the 50th percentile of preangiography plasma KIM-1 or YKL-40 levels would have reduced the required sample size by 30% (∼2,000 participants).

LIMITATIONS

Evaluation of prognostic enrichment does not account for changing trial costs, time needed to screen patients, or loss to follow-up. Most participants were male, limiting the generalizability of our findings.

CONCLUSIONS

Preangiography levels of injury and repair biomarkers modestly predict the development of MAKE-D and can be used to improve the efficiency of future CA-AKI trials.

Near-Infrared-Based Cerebral Oximetry for Prediction of Severe Acute Kidney Injury in Critically Ill Children After Cardiac Surgery

Supplemental Digital Content is available in the text.

Cerebral oximetry by near-infrared spectroscopy is used frequently in critically ill children but guidelines on its use for decision making in the PICU are lacking. We investigated cerebral near-infrared spectroscopy oximetry in its ability to predict severe acute kidney injury after pediatric cardiac surgery and assessed its additional predictive value to routinely collected data.

IL-6-mediated hepatocyte production is the primary source of plasma and urine neutrophil gelatinase-associated lipocalin during acute kidney injury

Neutrophil gelatinase associated lipocalin (NGAL, Lcn2) is the most widely studied biomarker of acute kidney injury (AKI). Previous studies have demonstrated that NGAL is produced by the kidney and released into the urine and plasma. Consequently, NGAL is currently considered a tubule specific injury marker of AKI. However, the utility of NGAL to predict AKI has been variable suggesting that other mechanisms of production are present. IL-6 is a proinflammatory cytokine increased in plasma by two hours of AKI and mediates distant organ effects. Herein, we investigated the role of IL-6 in renal and extra-renal NGAL production. Wild type mice with ischemic AKI had increased plasma IL-6, increased hepatic NGAL mRNA, increased plasma NGAL, and increased urine NGAL; all reduced in IL-6 knockout mice. Intravenous IL-6 in normal mice increased hepatic NGAL mRNA, plasma NGAL and urine NGAL. In mice with hepatocyte specific NGAL deletion (Lcn2hep-/-) and ischemic AKI, hepatic NGAL mRNA was absent, and plasma and urine NGAL were reduced. Since urine NGAL levels appear to be dependent on plasma levels, the renal handling of circulating NGAL was examined using recombinant human NGAL. After intravenous recombinant human NGAL administration to mice, human NGAL in mouse urine was detected by ELISA during proximal tubular dysfunction, but not in pre-renal azotemia. Thus, during AKI, IL-6 mediates hepatic NGAL production, hepatocytes are the primary source of plasma and urine NGAL, and plasma NGAL appears in the urine during proximal tubule dysfunction. Hence, our data change the paradigm by which NGAL should be interpreted as a biomarker of AKI.

Kidney Disease: Improving Global Outcomes in neonates with acute kidney injury after cardiac surgery

BACKGROUND

Acute kidney injury (AKI) after cardiac surgery (CS-AKI) in children with congenital heart disease is a serious complication closely associated with high morbidity and mortality. Kidney Disease: Improving Global Outcomes (KDIGO) AKI staging demonstrates high sensitivity for detecting AKI and predicting associated in-hospital mortality. However, neonatal-modified KDIGO criteria (n-KDIGO), recently introduced as a standard diagnostic tool, for CS-AKI have not been fully validated. Here, we evaluated the incidence of risk factors and postoperative outcomes of neonatal CS-AKI.

METHODS

We retrospectively studied 114 consecutive neonates who underwent cardiac surgery at the Kagoshima University Hospital. CS-AKI was classified using the n-KDIGO criteria. Risk adjustment in congenital heart surgery (RACHS-1) score was used to predict the complexity-adjusted mortality and % fluid overload (%FO) was used to monitor fluid balance in pediatric cardiac surgery.

RESULTS

Among 81 patients, neonatal CS-AKI occurred in 57 (70.4%) patients according to n-KDIGO criteria. Of these, 28 (34.6%) patients reached n-KDIGO 1, 17 (21.0%) reached n-KDIGO 2, and 12 (14.8%) reached n-KDIGO 3. Patients with CS-AKI had significantly higher vasoactive-inotropic score levels, longer operative times, and higher %FO than patients without CS-AKI. Notably, increased duration of cardiopulmonary bypass times and %FO were risk factors for the development of neonatal CS-AKI. The n-KDIGO-based severe AKI grade had higher risk of in-hospital mortality; however, the n-KDIGO-based mild AKI grade was not associated with any postoperative outcomes.

CONCLUSIONS

CS-AKI based on n-KDIGO criteria is common in neonates and is closely associated with higher mortality, especially in patients with severe CS-AKI.

Plasma Neutrophil Gelatinase-Associated Lipocalin Is Associated With Acute Kidney Injury and Clinical Outcomes in Neonates Undergoing Cardiopulmonary Bypass

OBJECTIVES

Acute kidney injury is a frequent complication following neonatal cardiac surgery and is associated with significant morbidity and mortality. The objectives of this study were to determine if plasma neutrophil gelatinase-associated lipocalin levels were associated with acute kidney injury and clinical outcomes in neonates with congenital heart disease undergoing cardiopulmonary bypass.

DESIGN

Retrospective single-center observational study.

SETTING

A pediatric cardiac ICU within a tertiary-care academic hospital.

PATIENTS

Patients age less than 30 days undergoing cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma neutrophil gelatinase-associated lipocalin peaked at 12 hours postcardiopulmonary bypass and more than doubled compared with preoperative levels. Higher preoperative and 24-hour postoperative neutrophil gelatinase-associated lipocalin levels were associated with acute kidney injury (r = 0.30, r = 0.49), longer duration of mechanical ventilation (r = 0.40, r = 0.51), ICU (r = 0.32, r = 0.33) and hospital lengths of stay (r = 0.28, r = 0.32), and total hospital charges (r = 0.35, r = 0.30; all p values < 0.05).

CONCLUSIONS

Both preoperative and 24-hour postoperative plasma neutrophil gelatinase-associated lipocalin levels are associated with acute kidney injury and worse clinical outcomes in neonates undergoing cardiac surgery. Plasma neutrophil gelatinase-associated lipocalin levels may have a role in risk stratification for predicting postoperative renal dysfunction as well as providing a potential clinical trajectory in the postoperative period.

The Association Between Cardiac Biomarker NT-proBNP and 30-Day Readmission or Mortality After Pediatric Congenital Heart Surgery

BACKGROUND

Very little is known about clinical and biomarker predictors of readmissions following pediatric congenital heart surgery. The cardiac biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP) can help predict readmission in adult populations, but the estimated utility in predicting risk of readmission or mortality after pediatric congenital heart surgery has not previously been studied. Our objective was to evaluate the association between pre- and postoperative serum biomarker levels and 30-day readmission or mortality for pediatric patients undergoing congenital heart surgery.

METHODS

We measured pre- and postoperative NT-proBNP levels in two prospective cohorts of 522 pediatric patients <18 years of age who underwent at least one congenital heart operation from 2010 to 2014. Blood samples were collected before and after surgery. We evaluated the association between pre- and postoperative NT-proBNP with readmission or mortality within 30 days of discharge, using multivariate logistic regression, adjusting for covariates based on the Society of Thoracic Surgeons (STS) Congenital Heart Surgery Mortality Risk Model.

RESULTS

The Johns Hopkins Children's Center cohort and the Translational Research Investigating Biomarker Endpoints in Acute Kidney Injury (TRIBE-AKI) cohort demonstrate event rates of 12.9% and 9.4%, respectively, for the composite end point. After adjustment for covariates in the STS congenital risk model, we did not find an association between elevated levels of NT-proBNP and increased risk of readmission or mortality following congenital heart surgery for either cohort.

CONCLUSIONS

In our two cohorts, preoperative and postoperative values of NT-proBNP were not significantly associated with readmission or mortality following pediatric congenital heart surgery. These findings will inform future studies evaluating multimarker risk assessment models in the pediatric population.

Prognostic value of neutrophil gelatinase-associated lipocalin and glycosylated hemoglobin for non-ST-segment elevation myocardial infarction patients with single concomitant chronic total occlusion following primary percutaneous coronary intervention: A prospective observational study

To investigate factors predicting the onset of major adverse cardiovascular and cerebrovascular events (MACCEs) after primary percutaneous coronary intervention (pPCI) for patients with non-ST-segment elevation infarction (NSTEMI) and single concomitant chronic total occlusion (CTO). Neutrophil gelatinase-associated lipocalin (NGAL) and glycosylated hemoglobin (HbA1c) both play essential role in cardiovascular and cerebrovascular homoeostasis. However, current knowledge of its predictive prognostic value is limited.422 patients with NSTEMI and CTO (59.7 ± 12.4 years, 74.2% men) who underwent successful pPCI were enrolled and followed for 2 years. Multivariate cox regression analysis and receiver operating characteristic (ROC) curve analysis were performed to determine the factors predicting MACCEs.140 patients (33.2%) experienced MACCEs in the follow-up period. Multivariate cox regression analysis found when we process the model with NGAL at admission, low left ventricular ejection fraction (LVEF, HR = 0.963, 95% CI 0.940 to 0.987, P = .003) and fasting blood glucose (HR = 1.078, 95% CI 1.002 to 1.159, P = .044), but not NGAL at admission, were independent predictors of 2 years MACCEs. While HbA1C (HR = 1.119, 95% CI 1.014 to 1.234, P = .025), LVEF (HR = 0.963, 95% CI 0.939 to 0.987, P = .003), estimated glomerular filtration rate (HR = 1.020, 95% CI 1.006 to 1.035, P = .006) and NGAL value 7 day (HR = 1.020, 95% CI 1.006 to 1.035, P = .006) showed their predictive value in another model. ROC analysis indicated NGAL 7 day (AUC = 0.680, P = .0054 and AUC = 0.622, P = .0005) and LVEF (AUC = 0.691, P = .0298 and AUC = 0.605, P = .0021) could predict both in-hospital and 2 years MACCEs, while higher NGAL at admission could only predict poorer in-hospital prognosis (AUC = 0.665, P = .0103). Further analysis showed the prognostic value of NGAL was particularly remarkable among those HbA1C<6.5%.Patients with NSTEMI and single concomitant CTO receiving pPCI with higher NGAL on 7 days during hospitalization are more likely to suffer 2 years MACCEs, particularly in those with lower HbA1C.

Found in Translation: Reasons for Optimism in the Pursuit to Prevent Chronic Kidney Disease After Acute Kidney Injury

Purpose of review:

The current review will discuss on the progress of studying the transition phase between acute kidney injury (AKI) and chronic kidney disease (CKD) through improved animal models, common AKI and CKD pathways, and how human studies may inform different translational approaches.

Sources of information:

PubMed and Google Scholar.

Methods:

A narrative review was performed using the main terms “acute kidney injury,” “chronic kidney disease,” “end-stage renal disease,” “animal models,” “review,” “decision-making,” and “translational research.”

Key findings:

The last decade has shown much progress in the study of AKI, including evidence of a pathophysiological link between AKI and CKD. We are now in a phase of redesigning animal models and discovering mechanisms that can replicate the pathological conditions of the AKI-to-CKD continuum. Translating these findings into the clinic is a barrier that must be overcome. To this end, current efforts include prediction of AKI onset and maladaptive repair, detecting patients susceptible to the progression of chronic maladaptive repair, and understanding shared signaling mechanisms between AKI and CKD.

Limitations:

This is a narrative review of the literature that is partially influenced by the knowledge, perspectives, and experiences of the authors and their research background.

Implications:

Overall, this new knowledge from the AKI-to-CKD continuum will help bridge the discontinuity that exists between animal models and patients, resulting in more effective translational biomarkers and therapeutics to test in known AKI pathologies thereby preventing the chronicity of kidney injury progression.

The role of kidney injury molecule-1 in predicting cardiorenal syndrome type 1 after diuretic treatment

Introduction

Cardiorenal syndrome (CRS) is defined as acute or chronic dysfunction in the heart and kidney due to important interactions between the heart and kidney disease. The aim of this study was to evaluate prediction of CRS type 1 by measuring kidney injury molecule-1 (KIM-1) and to establish early diagnosis of acute kidney injury (AKI).

Material and methods

During 2015–2016, 146 patients who were admitted to the emergency service with acute decompensated HF were included in the study. We investigated urinary KIM-1 levels in 146 consecutive patients with decompensated heart failure before and after diuretic treatment. Statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS – version 21.0)/Windows Statistical Software. P-values less than < 0.05 were considered significant.

Results

There was a moderate negative correlation between the percentage change of creatinine values and the percentage change of KIM-1 values (r = –0.357, p = 0.016). There was no statistically significant relationship between KIM-1 and the development of CRS type 1 (p = 0.011).

Conclusions

No statistically significant relationship was observed between KIM-1 levels and the development of CRS type 1. In addition, there was no correlation between mortality in patients and KIM-1 values. It is thought that KIM-1 is not a potential prognostic indicator because renal tubular damage is only one of many factors in the pathophysiology of CRS type 1 and heart failure.

Predictive value of plasma neutrophil gelatinase-associated lipocalin in acute charcoal-burning carbon monoxide poisoning

This study aimed to assess the feasibility of using the plasma neutrophil gelatinase-associated lipocalin (NGAL) level at the time of presentation in the emergency department (ED) to predict acute kidney injury (AKI) and the long-term neurological outcomes of acute charcoal-burning carbon monoxide (CO) poisoning. This retrospective study included 260 patients who suffered acute charcoal-burning CO poisoning. The median plasma NGAL concentration at the time of presentation in the ED after acute charcoal-burning CO poisoning was 78 (54–115) ng/ml. The NGAL level was an independent predictor of AKI development and could be used to stratify the severity of AKI. However, the area under the receiver operating characteristic curve (AUC) of the predictive model for AKI that included both the plasma NGAL level and clinical parameters was comparable to that of the predictive model including only the clinical parameters. The plasma NGAL level at the time of presentation in the ED was an independent factor predicting long-term neurological outcomes in patients who did not develop AKI. In these patients, the plasma NGAL level significantly improved the predictive accuracy of the model when used in combination with clinical parameters. In contrast, the plasma NGAL level was not associated with long-term neurological outcomes in patients who developed AKI. Measurement of the plasma NGAL level at the time ED presentation might improve the prediction of long-term neurological outcomes in patients who do not develop AKI after acute charcoal-burning CO poisoning. However, it might not offer additional benefit for AKI prediction compared to previously used markers.

Acute kidney injury overview: From basic findings to new prevention and therapy strategies

Acute kidney injury (AKI) is defined as a decrease in kidney function within hours, which encompasses both injury and impairment of renal function. AKI is not considered a pathological condition of single organ failure, but a syndrome in which the kidney plays an active role in the progression of multi-organ dysfunction. The incidence rate of AKI is increasing and becoming a common (8-16% of hospital admissions) and serious disease (four-fold increased hospital mortality) affecting public health costs worldwide. AKI also affects the young and previously healthy individuals affected by infectious diseases in Latin America. Because of the multifactorial pathophysiological mechanisms, there is no effective pharmacological therapy that prevents the evolution or reverses the injury once established; therefore, renal replacement therapy is the only current alternative available for renal patients. The awareness of an accurate and prompt recognition of AKI underlying the various clinical phenotypes is an urgent need for more effective therapeutic interventions to diminish mortality and socio-economic impacts of AKI. The use of biomarkers as an indicator of the initial stage of the disease is critical and the cornerstone to fulfill the gaps in the field. This review discusses emerging strategies from basic science toward the anticipation of features, treatment of AKI, and new treatments using pharmacological and stem cell therapies. We will also highlight bioartificial kidney studies, addressing the limitations of the development of this innovative technology.

Validation of acute kidney injury according to the modified KDIGO criteria in infants after cardiac surgery for congenital heart disease

AIM

We aimed to validate the incidence of, risk factors for, and postoperative outcomes of acute kidney injury (AKI) according to the modified Kidney Disease Improving Global Outcomes (m-KDIGO) criteria and compare this criteria with both the paediatric Risk, Injury, Failure, Loss, End-stage disease (pRIFLE) and Acute Kidney Injury Network (AKIN) criteria in infants after cardiac surgery.

METHODS

We retrospectively enrolled 145 consecutive infants who underwent open-heart surgery at Kagoshima University Hospital.

RESULTS

Acute kidney injury was present in 55 (37.9%), 111 (75.9%), and 95 (65.5%) patients according to the m-KDIGO, pRIFLE, and AKIN criteria, respectively. Among these, 71.9% of patients pRIFLE Risk patients and 60.5% of AKIN 1 patients were categorized in the 'no-AKI' group according to the m-KDIGO criteria. Low body weight (m-KDIGO odds ratio [OR], 0.73; P = 0.015; pRIFLE OR, 0.66; P = 0.001; AKIN OR 0.69, P = 0.002) and prolonged cross-clamp time (m-KDIGO OR, 1.02; <P = 0.001; pRIFLE OR, 1.02; P = 0.003; AKIN OR, 1.02; P = 0.001) were independent risk factors for the development of AKI. Further, m-KDIGO-based AKI grade was more strongly associated with higher incidence of requiring renal replacement therapy and mortality than both the pRIFLE- and AKIN- based AKI grade.

CONCLUSION

Application of the three criteria resulted in different AKI incidences, but each criterion could be useful for detecting risk factors for AKI. Notably, using m-KDIGO criteria provides more important subsequent postoperative outcomes. The m-KDIGO AKI criteria describe clinically relevant AKI in infants after cardiac surgery.

Acute Kidney Injury Following Cardiothoracic Surgery

This article reviews acute kidney injury following cardiothoracic surgery, addressing the full spectrum of the perioperative environment including preoperative, intraoperative, and postoperative factors for acute kidney injury. Topics discussed include pathophysiology, risk prediction scoring, diagnosis, prevention, treatment, and new directions for research.

Cyclophosphamide treatment for hypertension and renal injury in an experimental model of systemic lupus erythematosus

Cardiovascular disease is the major cause of mortality among patients with the autoimmune disorder systemic lupus erythematosus (SLE). Our laboratory previously reported that immunosuppression with mycophenolate mofetil, a common therapy in patients with SLE, attenuates the development of hypertension in an experimental model of SLE. Cyclophosphamide (CYC) is another common therapy for patients with SLE that has contributed to improved disease management; however, its impact on the development of hypertension associated with SLE is not clear. We tested whether treatment with CYC (25 mg/kg, once/week, IP injection) for 4 weeks would attenuate hypertension in an established female mouse model of SLE with hypertension (30-week-old NZBWF1 females). Plasma anti-dsDNA IgG levels, pathogenic for the disease, were lower in CYC-treated SLE mice compared to vehicle-treated SLE mice, suggesting efficacy of the therapy to suppress aberrant immune system function. Mean arterial pressure (MAP) was assessed by carotid artery catheters in conscious mice. Treatment did not attenuate the development of hypertension when compared to vehicle-treated SLE mice; however, urinary albumin excretion was lower in CYC-treated animals. Corresponding with the reduction in autoantibodies, data suggest that CYC treatment lowered circulating CD45R+ B cells. Paradoxically, circulating CD11b+ Ly6G+ neutrophils were increased in CYC-treated SLE mice compared to vehicle treated. Estrus cycling data also suggest that CYC treatment had an impact on ovarian function that may be consistent with reduced circulating estrogen levels. Taken together, these data suggest that CYC treatment attenuates autoantibody production and renal disease during SLE, but that the potential to affect MAP may be blunted by the increase in circulating neutrophils and CYC's impact on ovarian function.

[Biomarkers of cardiac surgery-associated acute kidney injury: a narrative review]

Cardiac surgery-related acute kidney injury (CSA-AKI) is a common and serious complication after cardiac surgery in adults. Currently, there is no specific examination method, and the diagnosis relying on serum creatinine and urine volume changes is of hysteresis. Biomarkers with the potential to predict CSA-AKI have become the focus in recent years. Clinical studies have shown that neutrophil gelatinase related lipid transporters and cell cycle inhibitors are of high diagnostic value; liver fatty acid binding protein can be used to assist in the diagnosis of CSA-AKI; microRNAs help to assess the poor prognosis of patients; the combined application of biomarkers may be used to predict the occurrence of CSA-AKI. CSA-AKI biomarkers provide the possibility for early clinical diagnosis and timely intervention, and are expected to become a new breakthrough in the diagnosis and treatment of CSA-AKI.

Biomarkers of Drug-Induced Kidney Toxicity

Blood urea nitrogen and serum creatinine are imperfect markers of kidney function because they are influenced by many renal and nonrenal factors independent of kidney function. A biomarker that is released directly into the blood or urine by the kidney in response to injury may be a better early marker of drug-induced kidney toxicity than blood urea nitrogen and serum creatinine. Urine albumin and urine protein, as well as urinary markers kidney injury molecule-1 (KIM-1), β2-microglobulin (B2M), cystatin C, clusterin, and trefoil factor-3 (TFF-3) have been accepted by the Food and Drug Administration and European Medicines Agency as highly sensitive and specific urinary biomarkers to monitor drug-induced kidney injury in preclinical studies and on a case-by-case basis in clinical trials. Other biomarkers of drug-induced kidney toxicity that have been detected in the urine of rodents or patients include IL-18, neutrophil gelatinase-associated lipocalin, netrin-1, liver-type fatty acid-binding protein (L-FABP), urinary exosomes, and TIMP2 (insulin-like growth factor-binding protein 7)/IGFBP7 (insulin-like growth factor-binding protein 7), also known as NephroCheck, the first Food and Drug Administration-approved biomarker testing platform to detect acute kidney injury in patients. In the future, a combined use of functional and damage markers may advance the field of biomarkers of drug-induced kidney toxicity. Earlier detection of drug-induced kidney toxicity with a kidney-specific biomarker may result in the avoidance of nephrotoxic agents in clinical studies and may allow for earlier intervention to repair damaged kidneys.

Early Postoperative Serum Creatinine Adjusted for Fluid Balance Precisely Predicts Subsequent Acute Kidney Injury After Cardiac Surgery

OBJECTIVES

Cumulative fluid overload may influence acute kidney injury (AKI) diagnosis due to the dilution effect. The authors hypothesized a small increase of early postoperative serum creatinine (SCr) adjusted for fluid balance might have superior discrimination ability in subsequent AKI prediction.

DESIGN

Retrospective analyses.

SETTING

A single-center study in a university hospital.

PARTICIPANTS

The study comprised 1,016 adult patients who underwent elective isolated or combined valve surgery in 2015.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Baseline characteristics, intraoperative parameters, and intraoperative and postoperative fluid balance were collected through a retrospective chart review. Early postoperative SCr level was drawn within 12 hours of surgical completion and then measured daily. Early relative changes of SCr were categorized as a cutoff value of 10% with or without adjustment for cumulative fluid balance. Kidney Disease: Improving Global Outcomes criteria were used to detect AKI. Logistic analyses were performed to determine risk factors for subsequent AKI with the inclusion of measured or fluid-adjusted early relative changes of SCr, respectively. In this study, 355 patients (34.9%) developed AKI. Multivariate logistic analyses showed age, weight, European System for Cardiac Operative Risk Evaluation II, and cardiopulmonary bypass duration were associated independently with the development of AKI. Model discrimination for AKI prediction was improved significantly when the addition of measured (area under the receiver operating characteristic curve [AUROC] 0.830) and fluid-adjusted early changes of SCr to the basic model (AUROC 0.850).

CONCLUSIONS

Early fluid-adjusted relative changes of SCr could improve the predictive ability for subsequent development of AKI in valve surgery patients.

Kidney Injury Molecule 1 (KIM-1) as an Early Predictor for Acute Kidney Injury in Post-Cardiopulmonary Bypass (CPB) in Open Heart Surgery Patients

INTRODUCTION

Postoperative acute kidney injury is associated with a higher mortality, a more complicated hospital course with longer hospital stay. Urinary kidney injury molecule 1 may play an important role as an early predictor of acute kidney injury post-cardiopulmonary in open heart surgery.

METHODS

We evaluated 45 patients who underwent open heart surgery from January 2016 to June 2016. Both urinary kidney injury molecule 1 and serum creatinine were evaluated before operation and 3hs and 24hs after operation. Acute kidney injury was diagnosed according to Kidney Disease: Improving Global Outcomes, 2012 guidelines.

RESULTS

In this study, 27 patients developed acute kidney injury. The three hour-post-surgery urinary kidney injury molecule 1 was significantly higher in the acute kidney injury group (P<0.015) and, at the same time, we did not find any significant difference in the serum creatinine levels between the two groups.

CONCLUSION

Although serum creatinine is still the gold standard for diagnosis of acute kidney injury searching for other new markers is mandatory. Urinary kidney injury molecule 1 can be used as simple noninvasive and specific biomarker for early diagnosis of acute kidney injury.

Pre-operative level of FGF23 predicts severe acute kidney injury after heart surgery in children

BACKGROUND

Early detection of acute kidney injury (AKI) after cardiac surgery has improved recently with the discovery and validation of novel urinary biomarkers. However, objective tools to predict the risk of AKI before the insult are still missing. We tested the hypothesis that pre-operative serum fibroblast growth factor 23 (FGF23) concentrations would be elevated in children who develop AKI after heart surgery with cardiopulmonary bypass (CPB). We also compared post-operative FGF23 concentrations to other biomarkers for early detection of AKI.

METHODS

Blood and urine samples were collected in a prospective observational study from 83 children with congenital heart disease. Severe AKI (sAKI) development (KDIGO stages II-III) in the first seven days after surgery was the primary outcome.

RESULTS

Thirty of 76 (39.5%) and 11/76 (14.5%) of patients developed AKI and sAKI, respectively. Pre-operative serum creatinine, cystatin C, and urine biomarker concentrations did not differ between sAKI patients and controls. Pre-operative serum FGF23 levels were higher in patients who developed sAKI (median [IQR] value of 819 RU/ml [397.7, 1196.8] vs. 324.3 RU/ml [124.6, 679.8] (p = 0.02). FGF23 12-24 h after the termination of CPB was also associated with sAKI in the first week after surgery (498 RU/ml [226, 928] vs. 1435 RU/ml [831, 12,996]).

CONCLUSIONS

Pre- and post-operative FGF23 levels are higher in children who develop sAKI after cardiac surgery. We suggest FGF23 may be able to detect sub-clinical kidney injury and can be used with demographic AKI risk factors to enhance post-operative sAKI risk prediction.

Acute Kidney Injury Biomarkers Predict an Increase in Serum Milrinone Concentration Earlier Than Serum Creatinine-Defined Acute Kidney Injury in Infants After Cardiac Surgery

BACKGROUND

Milrinone, an inotropic agent used ubiquitously in children after cardiac surgery, accumulates in acute kidney injury (AKI). We assessed if urinary AKI biomarkers are predictive of an increase in milrinone concentrations in infants after cardiac surgery.

METHODS

Multicenter prospective pilot study of infants undergoing cardiac surgery. Urinary AKI biomarkers were measured in the urine at specific time intervals after cardiopulmonary bypass initiation. AKI was defined using the Kidney Disease: Improving Global Outcomes serum creatinine criteria. Serum milrinone concentrations were measured at specific intervals after drug initiation, dose changes, and termination. Excessive milrinone activity was defined as a 20% increase in serum concentration between 6 and 36 hours after initiation. The temporal relationship between urinary AKI biomarker concentrations and a 20% increase in milrinone concentration was assessed.

RESULTS

AKI occurred in 31 (33%) of infants. Milrinone clearance was lower in patients with AKI (4.2 versus 5.6 L/h/70 kg; P = 0.02). Excessive milrinone activity was associated with development of serum creatinine-defined AKI [odds ratio (OR) 3.0; 95% confidence interval (CI), 1.21-7.39; P = 0.02]. Both tissue inhibitor metalloproteinase type 2 and insulin-like growth factor-binding protein type 7 (TIMP-2*IGFBP-7) ≥0.78 at 12 hours (OR 2.72; 95% CI, 1.01-7.38; P = 0.04) and kidney injury molecule 1 (KIM-1) ≥529.57 at 24 hours (OR 2.76; 95% CI, 1.06-7.17; P = 0.04) predicted excessive milrinone activity before a diagnosis of AKI.

CONCLUSIONS

In this pilot study, urine TIMP-2*IGFBP-7 and KIM-1 were predictive of AKI and excessive milrinone activity. Future studies that include a pharmacodynamics assessment of patient hemodynamics, excessive milrinone activity, and AKI biomarker concentrations may be warranted to integrate this concept into clinical practice.

The Japanese clinical practice guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention is necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

Efficacy of corticosteroids in prevention of acute kidney injury in neonates undergoing cardiac surgery-A randomized controlled trial

BACKGROUND

Heart surgery requiring cardiopulmonary bypass (CPB) causes an inflammatory response which may further induce acute kidney injury (AKI). In the present randomized controlled study we evaluated whether corticosteroids can prevent CPB related AKI in neonates undergoing heart surgery.

METHODS

Forty neonates were randomized to receive 2 mg/kg methylprednisolone followed by hydrocortisone infusion 0.2 mg/kg/h perioperatively with tapering doses for 5 days, or placebo administered in a similar fashion. The primary outcome was the inflammatory response (plasma concentrations of interleukins 6 and 10). The correspondence of the interleukin concentrations with AKI was analysed as secondary outcome. In addition, plasma and urine neutrophil gelatinase-associated lipocalin (NGAL), plasma cystatin C, and urine kidney injury molecule-1 (KIM-1) levels were measured.

RESULTS

Six patients (15%) developed post-operative AKI. No significant difference in the AKI occurrence between the treatment (n = 2) and the placebo (n = 4) groups could be found (risk ratio 2.00, 95% confidence interval 0.41-9.71; P = .661) despite significant reduction in inflammatory response in the treatment group. One patient in the treatment group and two patients in the placebo group required acute peritoneal dialysis. Plasma creatinine and cystatin C or urine NGAL and KIM-1 concentrations did not differ between the treatment and the placebo group.

CONCLUSIONS

Significantly reduced inflammatory reaction induced by corticosteroid treatment in neonates undergoing cardiac surgery did not reduce the incidence of AKI defined by KDIGO classification or decrease the rise of AKI biomarkers.

Cardiac Surgery-Associated Kidney Injury in Children and Renal Oximetry

OBJECTIVES

Cardiac surgery-associated acute kidney injury is common in children and associates with negative outcomes. Novel interventions to reduce cardiac surgery-associated acute kidney injury require knowledge of its pathophysiology. States of altered perfusion, oxygen delivery, and energy consumption occur during cardiopulmonary bypass and could protect against or contribute to renal cellular injury and recovery. Near-infrared spectroscopy is noninvasive technology for monitoring regional blood flow and tissue oxygenation. This study evaluated the relationship between renal regional oxygen saturation and cardiac surgery-associated acute kidney injury, using near-infrared spectroscopy monitoring before, during, and after cardiopulmonary bypass in children.

DESIGN

Prospective cohort study.

SETTING

Single-center, tertiary care pediatric hospital (Stollery Children's Hospital, Edmonton, AB, Canada).

PATIENTS

Children less than or equal to 10 kg undergoing congenital heart disease repair with cardiopulmonary bypass. Heart transplant, preoperative dialysis, sepsis, extracorporeal life support, congenital renal disease, and preoperative nephrotoxins were exclusions.

INTERVENTIONS

Renal regional near-infrared spectroscopy monitoring before, during, and after cardiopulmonary bypass.

MEASUREMENTS AND MAIN RESULTS

Outcome measure was cardiac surgery-associated acute kidney injury (defined according to Kidney Disease: Improving Global Outcomes criteria). Regional oxygen saturation was measured continuously using near-infrared spectroscopy (INVOS 5100C Cerebral/Somatic Oximeter; Medronic, Troy, MI) from time of anesthesia to time of transfer to intensive care. Cardiac surgery-associated acute kidney injury occurred in 65%. Lower baseline (precardiopulmonary bypass) regional oxygen saturation was associated with decreased risk of cardiac surgery-associated acute kidney injury (p = 0.01); children with baseline regional oxygen saturation in the highest tertile were 7.14 times more likely to get cardiac surgery- associated acute kidney injury (vs lowest tertile). Area under the curve for ability of baseline regional oxygen saturation to predict cardiac surgery-associated acute kidney injury was 0.73 (95% CI, 0.60-0.85). Children with lower baseline glomerular filtration rate had lower mean renal regional oxygen saturation.

CONCLUSIONS

Findings demonstrate that preoperative oxygen supply/demand balance is an important predictor of cardiac surgery-associated acute kidney injury, suggesting lower preoperative (and intraoperative) renal blood flow may be protective. There is not yet a definite link between remote ischemic preconditioning and prevention of cardiac surgery-associated acute kidney injury; however, renal protective effects of sublethal ischemia should continue to be explored.

The Japanese Clinical Practice Guideline for acute kidney injury 2016

Acute kidney injury (AKI) is a syndrome which has a broad range of etiologic factors depending on different clinical settings. Because AKI has significant impacts on prognosis in any clinical settings, early detection and intervention are necessary to improve the outcomes of AKI patients. This clinical guideline for AKI was developed by a multidisciplinary approach with nephrology, intensive care medicine, blood purification, and pediatrics. Of note, clinical practice for AKI management which was widely performed in Japan was also evaluated with comprehensive literature search.

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.

Prevention of Acute Kidney Injury in Children Undergoing Cardiac Surgery: A Narrative Review

Children undergoing cardiac surgery are at risk of developing acute kidney injury (AKI). Preventing cardiac surgery-associated AKI (CS-AKI) is important as it is associated with increased early- and long-term mortality and morbidity. Targeting modifiable risk factors (eg, avoiding poor renal perfusion, nephrotoxic drugs, and fluid overload) reduces the risk of CS-AKI. There is currently no strong evidence for the routine use of pharmacological approaches (eg, aminophylline, dexmedetomidine, fenoldopam, and steroids) to prevent CS-AKI. There is robust evidence to support the role of early peritoneal dialysis as a nonpharmacologic approach to prevent CS-AKI.

Biomarkers in acute kidney injury (AKI)

Acute kidney injury is common in critically ill patients and portends a significant impact on mortality, progressive chronic kidney disease, and cardiovascular disease and mortality. Though most physicians alter therapy depending on changes in serum creatinine, this often represents delayed intervention. Various AKI biomarkers have been discovered and validated to improve timely detection, differentiation and stratification into risk groups for progressive renal decline, need for renal replacement therapy or death. This chapter will review AKI biomarkers validated over the past decade. We also describe the clinical performance of the biomarkers. We suggest that using AKI biomarkers to complement serum creatinine (or cystatin C) and urine output will better integrate patient care through earlier recognition and clinical outcome prediction after AKI.

Urinary Tubular Injury Biomarkers Are Associated With ESRD and Death in the REGARDS Study

Introduction

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) and urinary kidney injury molecule-1 (uKIM-1) are established markers of subclinical acute kidney injury. In persons with reduced estimated glomerular filtration rate (eGFR) and albuminuria who are at high risk for end-stage renal disease (ESRD) and death, the associations of these urinary markers with incident ESRD or death is an area of active investigation.

Methods

Among 1472 black and white participants from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study with eGFR ≤60 ml/min per 1.73 m² (Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI] cystatin, 2012) and albumin-to-creatinine ratio (ACR) ≥30 mg/g, we evaluated the associations of baseline uNGAL and uKIM-1 with progression to ESRD and all-cause death. Cox models were sequentially adjusted for urinary creatinine, traditional risk factors, C-reactive protein, ACR, and eGFR.

Results

There were 257 ESRD events and 819 deaths over a median follow-up of 5.7 and 6.5 years, respectively. In demographic adjusted models, higher levels of uNGAL were associated with increased risk of ESRD and death, but these associations were attenuated in fully adjusted models including baseline eGFR for both ESRD (hazard ratio [HR] = 1.06 per doubling, 95% confidence interval [CI] 0.98-1.14) and death (HR = 1.04, 95% CI = 1.00-1.08). Higher levels of uKIM-1 were associated with increased risk of ESRD and death in demographic-adjusted models, and although attenuated in fully adjusted models, remained statistically significant for both ESRD (HR = 1.24 per doubling, 95% CI = 1.08-1.42) and death (HR = 1.10, 95% CI =1.03-1.19).

Conclusion

In this cohort of high-risk patients with baseline eGFR ≤60 ml/min per 1.73 m² and albuminuria, renal tubular injury is associated with higher mortality and progression to ESRD. Further studies are necessary to investigate the mechanism underlying this increased risk.

Kidney injury biomarkers 5 years after AKI due to pediatric cardiac surgery

BACKGROUND

We previously reported that children undergoing cardiac surgery are at high risk for long-term chronic kidney disease (CKD) and hypertension, although postoperative acute kidney injury (AKI) is not a risk factor for worse long-term kidney outcomes. We report here our evaluation of renal injury biomarkers 5 years after cardiac surgery to determine whether they are associated with postoperative AKI or long-term CKD and hypertension.

METHODS

Children aged 1 month to 18 years old undergoing cardiopulmonary bypass were recruited to this prospective cohort study. At 5 years after cardiac surgery, we measured urine interleukin-18, kidney injury molecule-1, monocyte chemoattractant protein-1, YKL-40, and neutrophil gelatinase-associated lipocalin (NGAL). Biomarker levels were compared between patients with AKI and those without. We also performed a cross-sectional analysis of the association between these biomarkers with CKD and hypertension.

RESULTS

Of the 305 subjects who survived hospitalization, four (1.3%) died after discharge, and 110 (36%) participated in the 5-year follow-up. Of these 110 patients, 49 (45%) had AKI. Patients with versus those without postoperative AKI did not have significantly different biomarker concentrations at 5 years after cardiac surgery. None of the biomarker concentrations were associated with CKD or hypertension at 5 years of follow-up, although CKD and hypertension were associated with a higher proportion of participants with abnormal NGAL levels.

CONCLUSIONS

Postoperative pediatric AKI is not associated with urinary kidney injury biomarkers 5 years after surgery. This may represent a lack of chronic renal injury after AKI, imprecise estimation of the glomerular filtration rate, the need for longer follow-up to detect chronic renal damage, or that our studied biomarkers are inadequate for evaluating subclinical chronic renal injury.