Long-term mortality associated with acute kidney injury in children following congenital cardiac surgery

Prediction of cardiac surgery associated acute kidney injury using response to loop diuretic and urine neutrophil gelatinase associated lipocalin

BACKGROUND

Cardiac surgery associated acute kidney injury (CS-AKI) is common. Urine response to loop diuretic and urine neutrophil gelatinase associated lipocalin (uNGAL) are separately associated with CS-AKI. We aimed to determine whether urine response to loop diuretic and uNGAL together were associated with postoperative day 2-4 CS-AKI.

METHODS

Two-center prospective observational study (ages 0-18 years). uNGAL (8-12 h after admission) (ng/mL) and urine response to loop diuretic (6 h for bolus furosemide and 12 h for infusion bumetanide) (mL/kg/hr) were measured. All diuretic doses were converted to furosemide equivalents. The primary outcome was day 2-4 CS-AKI. Patients were sub-phenotyped using a priori cutoffs (uNGAL +  ≥ 100 ng/mL and UOP +  < 1.5 mL/kg/hr) and optimal cutoffs (uNGAL +  ≥ 127 ng/mL and UOP +  ≤ 0.79 mL/kg/hr): 1) uNGAL-/UOP-, 2) uNGAL-/UOP + , 3) uNGAL + /UOP-, and 4) uNGAL + /UOP + . Multivariable regression was used to assess the association of uNGAL, UOP and each sub-phenotype with outcomes.

RESULTS

476 patients were included. CS-AKI occurred in 52 (10.9%). uNGAL was associated with 2.59-fold greater odds (95%CI: 1.52-4.41) of CS-AKI. UOP was not associated with CS-AKI. Compared with uNGAL + alone, uNGAL + /UOP + improved prediction of CS-AKI using a priori and optimal cutoffs respectively (AUC 0.70 vs. 0.75). Both uNGAL + /UOP + (IQR OR:4.63, 95%CI: 1.74-12.32) and uNGAL + /UOP- (IQR OR:5.94, 95%CI: 2.09-16.84) were associated with CS-AKI when compared with uNGAL-/UOP-.

CONCLUSIONS

uNGAL is associated with CS-AKI. The sub-phenotype association was largely driven by uNGAL. Future studies standardizing diuretic dose and timing may be needed to refine the combined performance for clinical decision making.

Expanding treatment horizons: transcatheter mitral valve-in-valve replacement in bridging to heart transplant

Transcatheter mitral valve (MV) replacement is an option in complex MV disease with potentially more predictable treatment outcomes and less invasiveness that increases the treatment spectrum to high-risk or non-surgical patients. We present an interesting case of failed MV bioprosthesis who presented with progressively worsening heart failure for heart transplant evaluation, but was successfully managed with transcatheter mitral valve-in-valve replacement (TMViVR). This case illustrates the pivotal role of TMViVR utilization in addressing complex cardiac scenarios, particularly when re-operative surgical MV replacement poses a high risk and also bridging the gap between the present and future heart transplantation preparations by paving the way for a well-prepared patient in the subsequent phase. The lifetime disease management and patient-centric approach with meticulous risk assessment reinforces the importance of shared decision-making in complex cases.

Persistent acute kidney injury and fluid accumulation with outcomes after the Norwood procedure: report from NEPHRON

BACKGROUND

Cardiac surgery-associated acute kidney injury (CS-AKI) is common, but its impact on clinical outcomes is variable. Parsing AKI into sub-phenotype(s) and integrating pathologic positive cumulative fluid balance (CFB) may better inform prognosis. We sought to determine whether durational sub-phenotyping of CS-AKI with CFB strengthens association with outcomes among neonates undergoing the Norwood procedure.

METHODS

Multicenter, retrospective cohort study from the Neonatal and Pediatric Heart and Renal Outcomes Network. Transient CS-AKI: present only on post-operative day (POD) 1 and/or 2; persistent CS-AKI: continued after POD 2. CFB was evaluated per day and peak CFB during the first 7 postoperative days. Primary and secondary outcomes were mortality, respiratory support-free and hospital-free days (at 28, 60 days, respectively). The primary predictor was persistent CS-AKI, defined by modified neonatal Kidney Disease: Improving Global Outcomes criteria.

RESULTS

CS-AKI occurred in 59% (205/347) neonates: 36.6% (127/347) transient and 22.5% (78/347) persistent; CFB > 10% occurred in 18.7% (65/347). Patients with either persistent CS-AKI or peak CFB > 10% had higher mortality. Combined persistent CS-AKI with peak CFB > 10% (n = 21) associated with increased mortality (aOR: 7.8, 95% CI: 1.4, 45.5; p = 0.02), decreased respiratory support-free (predicted mean 12 vs. 19; p < 0.001) and hospital-free days (17 vs. 29; p = 0.048) compared to those with neither.

CONCLUSIONS

The combination of persistent CS-AKI and peak CFB > 10% after the Norwood procedure is associated with mortality and hospital resource utilization. Prospective studies targeting intra- and postoperative CS-AKI risk factors and reducing CFB have the potential to improve outcomes.

Immune urinary biomarkers predict infant cardiac surgery-associated acute kidney injury

BACKGROUND

Acute kidney injury (AKI) occurs frequently after infant cardiac surgery and is associated with poor outcomes, including mortality and prolonged length of stay. AKI mechanisms are poorly understood, limiting therapeutic targets. Emerging data implicates dysregulated immune activation in post-cardiac surgery AKI development. We sought to identify immune-mediated AKI biomarkers after infant cardiopulmonary bypass (CPB)-assisted cardiac surgery.

METHODS

A single-center prospective study of 126 infants less than 1 year old undergoing CPB-assisted surgery enrolled between 10/2017 and 6/2019. Urine samples were collected before CPB and at 6, 24, 48, and 72 h after surgery. Immune-mediated biomarkers were measured using commercial ELISA and Luminex™ multiplex kits. Based on subject age, neonatal KDIGO (< 1 month) or KDIGO criteria defined AKI. The Kruskal-Wallis rank test determined the relationship between urinary biomarker measurements and AKI.

RESULTS

A total of 35 infants (27%) developed AKI. AKI subjects were younger, underwent more complex surgery, and had longer CPB time. Subjects with AKI vs. those without AKI had higher median urinary chemokine 10 (C-X-C motif) ligand levels at 24, 48, and 72 h, respectively: 14.3 pg/ml vs. 5.3 pg/ml, 3.4 pg/ml vs. 0.8 pg/ml, and 1.15 pg/ml vs. 0.22 pg/ml (p < 0.05) post-CPB. At 6 h post-CPB, median vascular cell adhesion protein 1 (VCAM) levels (pg/mL) were higher among AKI subjects (491 pg/ml vs. 0 pg/ml, p = 0.04).

CONCLUSIONS

Urinary CXCL10 and VCAM are promising pro-inflammatory biomarkers for early AKI detection and may indicate eventual AKI therapeutic targets. A higher resolution version of the Graphical abstract is available as Supplementary information.

Long-term outcomes of acute kidney injury in children

PURPOSE OF REVIEW

Acute kidney injury (AKI) affects up to 35% of all critically ill children and is associated with substantial short-term morbidity and mortality. However, the link between paediatric AKI and long-term adverse outcomes remains incompletely understood. This review highlights the most recent clinical data supporting the role of paediatric AKI as a risk factor for long-term kidney and cardiovascular consequences. In addition, it stresses the need for long-term surveillance of paediatric AKI survivors.

RECENT FINDINGS

Recent large-scale studies have led to an increasing understanding that paediatric AKI is a significant risk factor for adverse outcomes such as hypertension, cardiovascular disease and chronic kidney disease (CKD) over time. These long-term sequelae of paediatric AKI are most often observed in vulnerable populations, such as critically ill children, paediatric cardiac surgery patients, children who suffer from severe infections and paediatric cancer patients.

SUMMARY

A growing body of research has shown that paediatric AKI is associated with long-term adverse outcomes such as CKD, hypertension and cardiovascular disease. Although therapeutic pathways tailored to individual paediatric AKI patients are yet to be validated, we provide a framework to guide monitoring and prevention in children at the highest risk for developing long-term kidney dysfunction.

Transcatheter mitral valve replacement versus redo surgery for mitral prosthesis failure: A systematic review and meta-analysis

Background

Transcatheter mitral valve replacement (TMVR) has emerged as an alternative to redo surgery. TMVR compared with redo surgical mitral valve replacement (SMVR) in patients with mitral prosthesis failure remains limited. In this study, we performed a meta-analysis to assess the outcomes of TMVR (including valve-in-valve and valve-in-ring) versus redo surgery for mitral prosthesis failure.

Methods

We comprehensively searched the PubMed, Embase, and Cochrane library databases according to predetermined inclusion and exclusion criteria, and then we extracted data. We compared the outcomes of TMVR and redo SMVR for mitral prosthesis failure in terms of the in-hospital mortality, stroke, renal dysfunction, vascular complication, pacemaker implantation, exploration for bleeding, paravalvular leak, mean mitral valve gradient, 30-day mortality, and 1-year mortality.

Results

Nine retrospective cohort studies and a total of 3,038 patients were included in this analysis. Compared with redo SMVR for mitral prosthesis failure, TMVR was associated with lower in-hospital mortality [odds ratios (OR): 0.44; 95% confidence interval (CI): 0.30-0.64; P < 0.001], stroke (OR: 0.44; 95% CI: 0.29-0.67; P = 0.0001), renal dysfunction (OR: 0.52; 95% CI: 0.37-0.75; P = 0.0003), vascular complication (OR: 0.58; 95% CI: 0.43-0.78; P = 0.004), pacemaker implantation (OR: 0.23; 95% CI: 0.15-0.36; P < 0.00001), and exploration for bleeding (OR: 0.24; 95% CI: 0.06-0.96; P = 0.04). Conversely, redo SMVR had lower paravalvular leak (OR: 22.12; 95% CI: 2.81-174.16; P = 0.003). There was no difference in mean mitral valve gradient (MD: 0.04; 95% CI: -0.47 to 0.55; P = 0.87), 30-day mortality (OR: 0.65; 95% CI: 0.36-1.17; P = 0.15), and 1-year mortality (OR: 0.96; 95% CI: 0.63-1.45; P = 0.84).

Conclusion

In patients with mitral prosthesis failure, TMVR is associated with lower in-hospital mortality and lower occurrence of postoperative complications, except for paravalvular leak. TMVR offers a viable alternative to the conventional redo surgery in selected patients.

Long-Term Consequences of Acute Kidney Injury After Pediatric Cardiac Surgery: A Systematic Review

OBJECTIVE

The objective of this study was to evaluate the available data on long-term kidney dysfunction, hypertension, and mortality after cardiac surgery-associated acute kidney injury (AKI) in the pediatric population.

STUDY DESIGN

PubMed/MEDLINE, Embase, Scopus, and reference lists of relevant articles were searched for eligible studies published from inception through March 2022. Long-term outcomes after pediatric cardiac surgery complicated by AKI and those without were investigated.

RESULTS

We identified 14 studies published between 2013 and 2022 that included a total of 6701 patients (AKI: 1376 patients; no AKI: 5325 patients). These studies used different well-established classifications to define AKI. All the studies suggested that AKI after heart surgery is common in the pediatric patient population and reported a potential link between cardiac surgery-associated AKI and important clinical outcomes. However, only 4 out of 11 studies found a strong association between (absence of recovery from) cardiac surgery-associated AKI and risk of developing chronic kidney disease, and 3 out of 5 studies found a significant increase in mortality rates for pediatric patients who developed AKI after cardiac surgery. Only 1 out of 4 studies found an association between AKI and hypertension at 12 months postoperatively, but found no association at later follow-up times.

CONCLUSIONS

Although there is a trend, evidence on the long-term consequences of cardiac surgery-associated AKI in the pediatric population is mixed. Genetic syndromes, preexisting kidney disease, univentricular or cyanotic heart conditions, and/or high-complexity surgery may be more important for the development of kidney dysfunction by adolescence and early adulthood. Regardless, these children may benefit from a long-term kidney follow-up.

Filtering Down to Risks and Solutions: Risk Factors and Stratification After Pediatric Cardiac Surgery

Acute kidney injury after cardiac surgery (CS-AKI) is common in neonatal and pediatric populations and is a risk factor for poor outcomes, such as mortality and increased hospital resource utilization. This review presents a summary of CS-AKI risk factors, integration of biomarkers, and the need to improve risk stratification for targeting future clinical trials. To date, studies examining CS-AKI risk factors cannot be generalized easily owing to variability in patient age, surgical complexity or population, AKI definition, and center-specific practices. However, certain risk associations, such as younger age at surgery, history of prematurity, cardiopulmonary bypass time, and surgical complexity, have been identified across multiple, but not all, studies. CS-AKI appears to have different severity and duration phenotypes, and serum creatinine is limited in its ability to identify CS-AKI early and predict CS-AKI course. Treatment strategies are largely supportive, and efforts are ongoing to use biomarkers and clinical features to risk-stratify patients, which in turn may facilitate differential CS-AKI phenotyping and management with supportive care bundles, clinical decision support techniques, and modulation of modifiable risk factors.

Blood pressure variability during pediatric cardiac surgery is associated with acute kidney injury

BACKGROUND

Blood pressure variability (BPV), defined as the degree of variation between discrete blood pressure readings, is associated with poor outcomes in acute care settings. Acute kidney injury (AKI) is a common and serious postoperative complication of cardiac surgery with cardiopulmonary bypass (CPB) in children. No studies have yet assessed the association between intraoperative BPV during cardiac surgery with CPB and the development of AKI in children.

METHODS

A retrospective chart review of children undergoing cardiac surgery with CPB was performed. Intraoperative BPV was calculated using average real variability (ARV) and standard deviation (SD). Multiple regression models were used to examine the association between BPV and outcomes of AKI, hospital and intensive care unit (PICU) length of stay, and length of mechanical ventilation.

RESULTS

Among 231 patients (58% males, median age 8.6 months) reviewed, 51.5% developed AKI (47.9% Stage I, 41.2% Stage II, 10.9% Stage III). In adjusted models, systolic and diastolic ARV were associated with development of any stage AKI (OR 1.40, 95% CI 1.08-1.8 and OR 1.4, 95% CI 1.05-1.8, respectively). Greater diastolic SD was associated with longer PICU length of stay (β 0.94, 95% CI 0.62-1.2). When stratified by age, greater systolic ARV and SD were associated with AKI in infants ≤ 12 months, but there was no relationship in children > 12 months.

CONCLUSIONS

Greater BPV during cardiac surgery with CPB was associated with development of postoperative AKI in infants, suggesting that BPV is a potentially modifiable risk factor for AKI in this high-risk population.

Biomarkers of acute kidney injury in pediatric cardiac surgery

Acute kidney injury (AKI) is characterized by a sudden decrease in kidney function. Children with congenital heart disease are a special group at risk of developing AKI. We performed a systematic review of the literature to search for studies reporting the usefulness of novel urine, serum, and plasma biomarkers in the diagnosis and progression of AKI and their association with clinical outcomes in children undergoing pediatric cardiac surgery. In thirty studies, we analyzed the capacity to predict AKI and poor outcomes of five biomarkers: Cystatin C, Neutrophil gelatinase-associated lipocalin, Interleukin-18, Kidney injury molecule-1, and Liver fatty acid-binding protein. In conclusion, we suggest the need for further meta-analyses with the availability of additional studies.

Association between Elevated Urine Neutrophil Gelatinase-Associated Lipocalin and Postoperative Acute Kidney Injury in Neonates

OBJECTIVE

To examine the incidence of postoperative neonatal acute kidney injury (AKI) following general surgical procedures and to test the hypothesis that postoperative urine neutrophil gelatinase-associated lipocalin (uNGAL) concentrations predict AKI. The secondary objective was to evaluate for an association between AKI and hospital mortality.

STUDY DESIGN

Prospective observational study of infants undergoing abdominal and thoracic surgical procedures in the neonatal intensive care unit from October 2018 to March 2020. The primary outcome was incidence of neonatal AKI (defined by the neonatal modified Kidney Diseases Improving Global Outcomes criteria) following each procedure to postoperative day 5. Severe AKI was defined as stage 2 or 3 AKI. Urine samples were obtained pre- and postoperatively at 6 time points to evaluate for levels of uNGAL. Secondary outcomes were in-hospital mortality and length of stay.

RESULTS

Subjects (n = 141) underwent a total of 192 general surgical procedures during the study period. Neonatal AKI and severe AKI occurred following 36 (18%) and 15 (8%) procedures (n = 33 subjects). Percent change of uNGAL from 24 hours preoperatively to 24 hours postoperatively was greater in subjects with neonatal AKI (190.2% [IQR 0.0, 1666.7%] vs 0.7% [IQR -31.2%,140.2%], P = .0374). The strongest association of uNGAL and AKI occurred at 24 hours postoperatively (area under the receiver operator curves of 0.81, 95% CI 0.72, 0.89). Increased mortality risk was observed in subjects with any postoperative AKI (aOR 11.1 95% CI 2.0, 62.8, P = .0063) and severe AKI (aOR 13.8; 95% CI 3.0, 63.1, P = .0007).

CONCLUSION

Elevation in uNGAL 24 hours postoperative was associated with AKI. Neonates with postoperative AKI had increased mortality.

Association of pediatric cardiac surgery-associated acute kidney injury with post-discharge healthcare utilization, mortality and kidney outcomes

BACKGROUND

Acute kidney Injury (AKI) in children undergoing cardiac surgery (CS) is strongly associated with hospital morbidity. Post-discharge CS AKI outcomes are less clear. We evaluated associations between AKI and post-discharge (a) healthcare utilization, (b) chronic kidney disease (CKD) or hypertension and (c) mortality.

METHODS

This is a retrospective two-centre cohort study of children surviving to hospital discharge after CS. Primary exposures were post-operative ≥Stage 1 AKI and ≥Stage 2 AKI defined by Kidney Disease Impoving Global Outcomes. Association of AKI with time to outcomes was determined using multivariable Cox-Proportional Hazards analysis.

RESULTS

Of 350 participants included (age 3.1 (4.5) years), 180 [51.4%] developed AKI and 60 [17.1%] developed ≥Stage 2 AKI. Twenty-eight (9%) participants developed CKD or hypertension (composite outcome), and 17 (5%) died within 5 years of discharge. Post-operative ≥Stage 1 and ≥Stage 2 AKI were not associated with post-discharge hospitalizations, emergency room (ER) visits, physician visits or CKD or hypertension in adjusted analyses. A trend was observed between ≥Stage 2 AKI and mortality but was not statistically significant. In unadjusted stratified analyses, AKI was associated with post-discharge hospitalizations in children with RACHS-1 score ≥3, complex chronic disease classification and children living in urban areas.

CONCLUSIONS

Post-CS AKI is not associated with post-discharge healthcare utilization, death and CKD or hypertension, though it may be associated with healthcare utilization in more complex paediatric CS children. Studies should aim to better understand post-CS healthcare utilization patterns and non-AKI risk factors for CKD, hypertension and mortality, to reduce adverse long-term outcomes after CS.

Acute Kidney Injury Post-cardiac Surgery in Infants and Children: A Single-Center Experience in a Developing Country

Introduction: The incidence of acute kidney injury (AKI) in pediatric patients following cardiac surgery varies between 15 and 64%, with a mortality rate of 10-89% among those requiring dialysis. This variation in the incidence and mortality of AKI across studies is probably due to the inconsistent definitions used for AKI. The purpose of this study is to present our experience with AKI post-cardiac surgery with emphasis on predisposing or aggravating factors. Patients and Methods: We evaluated the incidence of AKI using the KDIGO criteria in 150 infants and children undergoing cardiac surgeries between 2015 and 2017. Post-operatively, all patients were admitted to the pediatric intensive care unit (PICU) at a tertiary care center in a developing country. This is a retrospective chart review in which data collected included age, gender, type of heart disease, prior cardiac surgeries, RACHS-1 category, and pre- and post-operative creatinine levels. Neonates were not included in this study. Results: Six percent of the studied patients were below 1 year of age, 84% 1-10 years, and 10% 10-18 years. Fourteen patients (9.3%) developed AKI. Patients with cyanotic heart disease were more prone to develop AKI (78%) compared to those with non-cyanotic heart disease (44%). Children with AKI had a higher length of stay in PICU, 2.56 ± 1.44 vs. 4 ± 2.66 (p- 0.02). Serum lactic acid was higher in patients who developed AKI with a mean value of 6.8 ± 6.9 vs. 2.85 ± 1.55 mmol/l in the non-AKI group (p- 0.03). Lower hemoglobin levels and hyperlactic acidemia were significantly more prevalent in the AKI group. There were five deaths in this series (3.3%), and four of those (80%) were in the AKI group. Conclusion: Using the KDIGO criteria, the incidence of AKI in infants and children following cardiac surgery was 9.3%. This is slightly lower than in previously published studies where the range was between 15 and 64%. Children with cyanotic cardiac disease, hyperlactic acidemia, and anemia were more prone to developing AKI. Identifying patients at risk might help decrease the risk of post-operative AKI.

The association of acute kidney injury with hospital readmission and death after pediatric cardiac surgery

Background

Acute kidney injury (AKI) in children undergoing cardiac surgery (CS) is strongly associated with increased hospital mortality and length of stay. The association of AKI with postdischarge outcomes is unclear. We evaluated the association of AKI with all-cause readmissions and death within 30 days and 1 year of CS discharge.

Methods

This was a prospective, 3-center cohort study of children after CS with cardiopulmonary bypass. The primary exposures were postoperative ≥stage 1 AKI and ≥stage 2 AKI defined by Kidney Disease: Improving Global Outcomes AKI definition. Two separate outcomes were hospital readmission and death within 30 days and 1 year of discharge. Association of AKI with time to outcomes was determined using multivariable Cox-proportional hazards analysis. Age, The Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery risk adjustment tool score ≥3, cardiopulmonary bypass >120 minutes, and cyanotic heart disease were evaluated as effect modifiers.

Results

Of 402 participants included (median age 1.8 years [interquartile range 0.4, 5.2]), 32 (8.0%) and 109 (27.1%) were readmitted; 7 (1.7%) and 9 (2.2%) died within 30 days and 1 year of CS, respectively. AKI was not associated with readmission at 30 days or 1 year postdischarge. ≥Stage 2 AKI (adjusted hazard ratio, 11.68 [1.88, 72.61]) was associated with mortality 30 days post-CS.

Conclusions

Postoperative AKI was not associated with readmission at 30 days and 1-year postdischarge. However, more severe AKI (≥stage 2) appears to be associated with increased morality risk at 30 days post-CS.

Effect of Prophylactic Levosimendan on All-Cause Mortality in Pediatric Patients Undergoing Cardiac Surgery-An Updated Systematic Review and Meta-Analysis

Background: Levosimendan, a calcium sensitizer, enhances the myocardial function by generating more energy-efficient myocardial contractility than that achieved through adrenergic stimulation with catecholamines. We conducted this meta-analysis to primarily investigate the effects of levosimendan on all-cause mortality in pediatric patients undergoing cardiac surgery under cardiopulmonary bypass. Methods: The databases of Pubmed, Embase, and Cochrane Library were searched till 21st March 2020. The eligible criteria were participants with age<18 year and undergoing cardiac surgery for congenital heart disease (CHD), and studies of comparison between levosimendan and placebo or other inotropes. Stata version 12.0 was used to perform statistical analyses. Results: Six randomized controlled trials (RCTs) and 1 case-control trial (CCT) including 436 patients were included. The results showed that levosimendan did not significantly decrease all-cause mortality compared with control drugs (and placebo) in children undergoing cardiac surgery (P = 0.403). Perioperative prophylactic levosimendan administration strikingly decreased the low cardiac output syndrome (LCOS) incidence (P = 0.016) but did not significantly reduce acute kidney injury (AKI) incidence (P = 0.251) and shorten mechanical ventilation and ICU stay time compared with other inotropes and placebo by analyzing the included literatures [mechanical ventilation (or intubation) time: P = 0.188; ICU stay time: P = 0.620]. Conclusions: Compared with other inotropes and placebo, perioperative prophylactic administration of levosimendan did not decrease the rates of mortality and AKI and shorten the time of mechanical ventilation (or intubation) and ICU stay but demonstrated a significant reduction in LCOS incidence after corrective surgery in pediatric patients for CHD. Due to limited number of included studies, the current data were insufficient to make the conclusions.

Long-term Mortality After Acute Kidney Injury in the Pediatric ICU

OBJECTIVES

(1) To evaluate the association between acute kidney injury (AKI) in the PICU and long-term mortality and (2) to determine the extent to which adding the urine output (UO)-defined AKI alters the association.

METHODS

A 2-center retrospective cohort study of children (≤18 years old) admitted to the PICU between 2003 and 2005 for noncardiac surgery, with follow-up until 2010. Patients with end stage renal disease, no provincial health insurance number, who died during hospitalization, or could not be linked to administrative data were excluded. One hospitalization per patient was included. AKI was defined by using serum creatinine criteria and/or UO criteria. Mortality was ascertained by using administrative data. Cox regression analysis was performed to evaluate the association between AKI and long-term mortality.

RESULTS

The study population included 2041 patients (55.7% male, mean admission age 6.5 ± 5.8 years). Of 2041 hospital survivors, 9 (0.4%) died within 30 days, 51 (2.5%) died within 1 year, and 118 (5.8%) died within 5 to 7 years postdischarge. AKI was independently associated with 5- to 7-year mortality (adjusted hazard ratio [95% confidence interval]: 3.10 [1.46-6.57] and 3.38 [1.63-7.02], respectively). Including UO did not strengthen the association.

CONCLUSIONS

AKI is associated with 5- to 7-year mortality. Because this is an observational study we cannot determine if AKI is causative of mortality or of the pathophysiology. However, patients with AKI represent a high-risk group. It is reasonable that these patients be considered for targeted follow-up until future researchers better elucidate these relationships.

Acute Kidney Injury and Fluid Overload in Pediatric Cardiac Surgery

PURPOSE OF REVIEW

Acute kidney injury (AKI) and fluid overload affect a large number of children undergoing cardiac surgery, and confers an increased risk for adverse complications and outcomes including death. Survivors of AKI suffer long-term sequelae. The purpose of this narrative review is to discuss the short and long-term impact of cardiac surgery associated AKI and fluid overload, currently available tools for diagnosis and risk stratification, existing management strategies, and future management considerations.

RECENT FINDINGS

Improved risk stratification, diagnostic prediction tools and clinically available early markers of tubular injury have the ability to improve AKI-associated outcomes. One of the major challenges in diagnosing AKI is the diagnostic imprecision in serum creatinine, which is impacted by a variety of factors unrelated to renal disease. In addition, many of the pharmacologic interventions for either AKI prevention or treatment have failed to show any benefit, while peritoneal dialysis catheters, either for passive drainage or prophylactic dialysis may be able to mitigate the detrimental effects of fluid overload.

SUMMARY

Until novel risk stratification and diagnostics tools are integrated into routine practice, supportive care will continue to be the mainstay of therapy for those affected by AKI and fluid overload after pediatric cardiac surgery. A viable series of preventative measures can be taken to mitigate the risk and severity of AKI and fluid overload following cardiac surgery, and improve care.

Risk Factors for Recurrent Acute Kidney Injury in Children Who Undergo Multiple Cardiac Surgeries: A Retrospective Analysis

OBJECTIVES

Determine the risk factors for repeated episodes of acute kidney injury in children who undergo multiple cardiac surgical procedures.

DESIGN

Single-center retrospective chart review.

SETTING

Cardiac ICU at a quaternary pediatric care center.

PATIENTS

Birth to 18 years who underwent at least two cardiac surgical procedures with cardiopulmonary bypass.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One-hundred eighty patients underwent two cardiac surgical procedures and 89 underwent three. Acute kidney injury was defined by the Kidney Disease: Improving Global Outcomes serum creatinine criteria. Acute kidney injury frequency was 26% (n = 46) after surgery 1, 20% (n = 36) after surgery 2, and 24% (n = 21) after surgery 3, with most acute kidney injury occurring on postoperative days 1 and 2. The proportion of patients with severe acute kidney injury increased from surgery 1 to surgery 3. Patients with acute kidney injury had a significantly longer duration of ventilation and length of stay after each surgery. The odds of acute kidney injury after surgery 3 was 2.40 times greater if acute kidney injury was present after surgery 1 or 2 (95% CI, 1.26-4.56; p = 0.008) after adjusting for confounders. The time between surgeries was not significantly associated with acute kidney injury (p = 0.85).

CONCLUSIONS

In a heterogeneous population of pediatric patients with congenital heart disease undergoing multiple cardiopulmonary bypass surgeries, odds of acute kidney injury after a third surgery was increased by the presence of acute kidney injury after prior procedures. Time between surgery did not play a role in increasing odds of acute kidney injury. Further studies in a larger multicenter investigation are necessary to confirm these findings.

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.

Neonatal and Paediatric Heart and Renal Outcomes Network: design of a multi-centre retrospective cohort study

BACKGROUND

Cardiac surgery-associated acute kidney injury is common. In order to improve our understanding of acute kidney injury, we formed the multi-centre Neonatal and Pediatric Heart and Renal Outcomes Network. Our main goals are to describe neonatal kidney injury epidemiology, evaluate variability in diagnosis and management, identify risk factors, investigate the impact of fluid overload, and explore associations with outcomes.

METHODS

The Neonatal and Pediatric Heart and Renal Outcomes Network collaborative includes representatives from paediatric cardiac critical care, cardiology, nephrology, and cardiac surgery. The collaborative sites and infrastructure are part of the Pediatric Cardiac Critical Care Consortium. An acute kidney injury module was developed and merged into the existing infrastructure. A total of twenty-two participating centres provided data on 100-150 consecutive neonates who underwent cardiac surgery within the first 30 post-natal days. Additional acute kidney injury variables were abstracted by chart review and merged with the corresponding record in the quality improvement database. Exclusion criteria included &gt;1 operation in the 7-day study period, pre-operative renal replacement therapy, pre-operative serum creatinine &gt;1.5 mg/dl, and need for extracorporeal support in the operating room or within 24 hours after the index operation.

RESULTS

A total of 2240 neonatal patients were enrolled across 22 centres. The incidence of acute kidney injury was 54% (stage 1 = 31%, stage 2 = 13%, and stage 3 = 9%).

CONCLUSIONS

Neonatal and Pediatric Heart and Renal Outcomes Network represents the largest multi-centre study of neonatal kidney injury. This new network will enhance our understanding of kidney injury and its complications.

Acute kidney injury after pediatric cardiac surgery

Acute kidney injury (AKI) is a common complication of pediatric cardiac surgery and is associated with increased morbidity and mortality. Literature of AKI after pediatric cardiac surgery is comprehensively reviewed in terms of incidence, risk factors, biomarkers, treatment and prognosis. The novel RIFLE (pediatric RIFLE for pediatrics), Acute Kidney Injury Network (AKIN) and Kidney Disease Improving Global Outcomes (KDIGO) criteria have brought about unified diagnostic standards and comparable results for AKI after cardiac surgery. Numerous risk factors, either renal or extrarenal, can be responsible for the development of AKI after cardiac surgery, with low cardiac output syndrome being the most pronounced predictor. Early fluid overload is also crucial for the occurrence of AKI and prognosis in pediatric patients. Three sensitive biomarkers, neutrophil gelatinase-associated lipocalin, cystatin C (CysC) and liver fatty acid-binding protein, are regarded as the earliest (increase at 2-4 h), and another two, kidney injury molecule-1 and interleukin-18 represent the intermediate respondents (increase at 6-12 h after surgery). To ameliorate the cardiopulmonary bypass techniques, improve renal perfusion and eradicate the causative risk factors are imperative for the prevention of AKI in pediatric patients. The early and intermediate biomarkers are helpful for an early judgment of occurrence of postoperative AKI. Improved survival has been achieved by prevention, renal support and modifications of hemofiltration techniques. Further development is anticipated in small children.

Associations of Perioperative Renal Oximetry Via Near-Infrared Spectroscopy, Urinary Biomarkers, and Postoperative Acute Kidney Injury in Infants After Congenital Heart Surgery: Should Creatinine Continue to Be the Gold Standard?

OBJECTIVES

Examine the relationship between perioperative renal regional tissue oximetry, urinary biomarkers, and acute kidney injury in infants after congenital cardiac surgery with cardiopulmonary bypass.

DESIGN

Prospective, observational.

SETTING

Cardiac operating room and cardiac ICU.

PATIENTS

Neonates and infants without history of kidney injury or anatomic renal abnormality.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Renal regional tissue oximetry was measured intraoperatively and for 48 hours postoperatively. Urinary levels of neutrophil gelatinase-associated lipocalin and tissue inhibitor of metalloproteinases 2 together with insulin-like growth factor-binding protein 7 were measured preoperatively, 2, 12, and 24 hours postoperatively. Patients were categorized as no acute kidney injury, stage 1, or Stage 2-3 acute kidney injury using the Kidney Disease: Improving Global Outcomes criteria with 43 of 70 (61%) meeting criteria for any stage acute kidney injury. Stage 2-3 acute kidney injury patients had higher tissue inhibitor of metalloproteinases 2, insulin-like growth factor-binding protein 7 at 2 hours (0.3 vs 0.14 for stage 1 acute kidney injury and 0.05 for no acute kidney injury; p = 0.052) and 24 hours postoperatively (1.71 vs 0.27 for stage 1 acute kidney injury and 0.19 for no acute kidney injury, p = 0.027) and higher neutrophil gelatinase-associated lipocalin levels at 24 hours postoperatively (10.3 vs 3.4 for stage 1 acute kidney injury and 6.2 for no acute kidney injury, p = 0.019). Stage 2-3 acute kidney injury patients had lower mean cardiac ICU renal regional tissue oximetry (66% vs 79% for stage 1 acute kidney injury and 84% for no acute kidney injury, p = 0.038). Regression analyses showed that tissue inhibitor of metalloproteinases 2, insulin-like growth factor-binding protein 7 at 2 hours postoperatively and nadir intraoperative renal regional tissue oximetry to be independent predictors of postoperative kidney damage as measured by urinary neutrophil gelatinase-associated lipocalin.

CONCLUSIONS

We observed modest differences in perioperative renal regional tissue oximetry and urinary biomarker levels compared between acute kidney injury groups classified by creatinine-dependent Kidney Disease: Improving Global Outcomes criteria, but there were significant correlations between renal regional tissue oximetry, tissue inhibitor of metalloproteinases 2, insulin-like growth factor-binding protein 7, and postoperative neutrophil gelatinase-associated lipocalin levels. Kidney injury after infant cardiac surgery may be undetectable by functional assessment (creatinine) alone, and continuous monitoring of renal regional tissue oximetry may be more sensitive to important subclinical acute kidney injury.

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.

Association Between Early Postoperative Acetaminophen Exposure and Acute Kidney Injury in Pediatric Patients Undergoing Cardiac Surgery

IMPORTANCE

Acute kidney injury (AKI) is a common and serious complication for pediatric cardiac surgery patients associated with increased morbidity, mortality, and length of stay. Current strategies focus on risk reduction and early identification because there are no known preventive or therapeutic agents. Cardiac surgery and cardiopulmonary bypass lyse erythrocytes, releasing free hemoglobin and contributing to oxidative injury. Acetaminophen may prevent AKI by reducing the oxidation state of free hemoglobin.

OBJECTIVE

To test the hypothesis that early postoperative acetaminophen exposure is associated with reduced risk of AKI in pediatric patients undergoing cardiac surgery.

DESIGN, SETTING, AND PARTICIPANTS

In this retrospective cohort study, the setting was 2 tertiary referral children's hospitals. The primary and validation cohorts included children older than 28 days admitted for cardiac surgery between July 1, 2008, and June 1, 2016. Exclusion criteria were postoperative extracorporeal membrane oxygenation and inadequate serum creatinine measurements to determine AKI status.

EXPOSURES

Acetaminophen exposure in the first 48 postoperative hours.

MAIN OUTCOMES AND MEASURES

Acute kidney injury based on Kidney Disease: Improving Global Outcomes serum creatinine criteria (increase by ≥0.3 mg/dL from baseline or at least 1.5-fold more than the baseline [to convert to micromoles per liter, multiply by 88.4]) in the first postoperative week.

RESULTS

The primary cohort (n = 666) had a median age of 6.5 (interquartile range [IQR], 3.9-44.7) months, and 341 (51.2%) had AKI. In unadjusted analyses, those with AKI had lower median acetaminophen doses than those without AKI (47 [IQR, 16-88] vs 78 [IQR, 43-104] mg/kg, P < .001). In logistic regression analysis adjusting for age, cardiopulmonary bypass time, red blood cell distribution width, postoperative hypotension, nephrotoxin exposure, and Risk Adjustment for Congenital Heart Surgery score, acetaminophen exposure was protective against postoperative AKI (odds ratio, 0.86 [95% CI, 0.82-0.90] per each additional 10 mg/kg). Findings were replicated in the validation cohort (n = 333), who had a median age of 14.1 (IQR, 3.9-158.2) months, and 162 (48.6%) had AKI. Acetaminophen doses were 60 (95% CI, 40-87) mg/kg in those with AKI vs 70 (95% CI, 45-94) mg/kg in those without AKI (P = .03), with an adjusted odds ratio of 0.91 (95% CI, 0.84-0.99) for each additional 10 mg/kg.

CONCLUSIONS AND RELEVANCE

These results indicate that early postoperative acetaminophen exposure may be associated with a lower rate of AKI in pediatric patients who undergo cardiac surgery. Further analysis to validate these findings, potentially through a prospective, randomized trial, may establish acetaminophen as a preventive agent for AKI.

Hemodynamic Profile of Acute Kidney Injury Following the Fontan Procedure: Impact of Renal Perfusion Pressure

BACKGROUND

Acute kidney injury (AKI) is common following cardiopulmonary bypass. Fontan completion may result in systemic venous hypertension and low cardiac output, reducing renal perfusion pressure (RPP) and further increasing the risk of AKI. We investigated the incidence and risk factors for post-Fontan AKI.

METHODS

Single-center retrospective study of children undergoing Fontan completion from 2005 to 2012. Demographic and hemodynamic variables were assessed for association with AKI. Subgroup analysis was performed on patients with high-grade AKI (creatinine increase of ≥2.0 × baseline). Vital sign data were collected hourly for the first postoperative day.

RESULTS

A total of 186 patients underwent Fontan at 3.1 (2.5-3.8) years of age and 13.5 kg (12.2-15.1). Acute kidney injury occurred in 97 (52%) patients, with high-grade AKI in 52 (28%). Univariate analysis identified reduced RPP in patients with AKI compared to those without AKI, 50 (45-56) mm Hg versus 58 (54-61) mm Hg ( P < .0001), due to lower mean arterial blood pressure, 63 (60-69) versus 70 (66-73) mm Hg ( P < .0001), and higher central venous pressure, 14 (12-16) versus 13 (11-14) mm Hg, ( p < .0001). Multivariable logistic regression and classification tree analyses further identified elements of RPP as significant predictors of AKI, especially high-grade AKI. Postoperative intubation was linked to AKI development. Patients with AKI had decreased postoperative urine output with increased colloid requirements, duration of chest tube insertion, and hospital length of stay.

CONCLUSION

Acute kidney injury occurs frequently following the Fontan procedure. Associated factors include reduced RPP, high colloid requirements, and postoperative intubation. Targeted hemodynamic interventions may serve to reduce the incidence of post-Fontan AKI.

AKI after pediatric cardiac surgery for congenital heart diseases-recent developments in diagnostic criteria and early diagnosis by biomarkers

Background

Acute kidney injury (AKI) after cardiac surgery in children with congenital heart disease is a common complication. AKI is also associated with high morbidity and mortality. The Kidney Diseases Improving Global Outcomes (KDIGO) criteria for AKI classification are now widely used for the definition of AKI. It is noteworthy that a statement about children was added to the criteria. Many studies aimed at finding useful biomarkers are now being performed by using these criteria. Clinicians should be aware of the recent progress in understanding AKI in children.

Main contents

Unlike adult patients, young age is one of the major risk factors for AKI in pediatric cardiac surgery. The mechanism of the development of AKI in children might be different from that in adults because the surgical procedure and CPB technique in pediatric patients are greatly different from those in adult patients.

There are many biomarkers for early detection of AKI, and some of them are widely used in hospitals. One of the major benefits of such biomarkers is the rapidness of expression for detecting increases in their expression levels. Neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, cystatin C, and albumin have been investigated in some studies, and the usefulness of these biomarkers for detection of AKI and diagnosis of disease severity has been shown.

Although there are many interventions for preventing and treating AKI after cardiac surgery in children, there is still no specific effective treatment. Peritoneal dialysis is effective for only maintaining a negative fluid balance early after cardiac surgery. The long-term prognosis of AKI is an issue of interest. Although mortality and morbidity of AKI in the acute phase of disease remain high, the long-term condition in pediatric patients is relatively acceptable unlike in adults.

Conclusions

KDIGO criteria are advocated as a diagnostic tool for common perception. Early recognition and intervention for AKI can be achieved by using several biomarkers. Further studies are needed to establish effective treatment for AKI.

Risk Factors and Outcome of Acute Kidney Injury after Congenital Heart Surgery: A Prospective Observational Study

Backgrounds and Aims:

Acute kidney injury (AKI) is a frequent event after congenital heart surgery with increased mortality and morbidity. We investigated frequency, risk factors, and associated morbidity and mortality of AKI after pediatric cardiac surgery at a single institution.

Methods:

Children undergoing congenital heart surgery from March 2013 to February 2016 were assessed for development of AKI based on modified pediatric Risk, Injury, Failure, Loss, and End-stage renal disease criteria. They were also investigated for predictive risk factors, associated mortality, and morbidity including duration of mechanical ventilation, Intensive Care Unit (ICU), and hospital length of stay.

Results:

Five hundred and nineteen patients were recruited during the study period including 259 (49.9%) males and 260 (50.1%) females. AKI was seen in 150 (28.9%) patients including 101 (67.3%), 42 (28%), and 7 (4.7%) cases with risk, injury, and failure stages, respectively. Patients with AKI had longer ventilation time (P = 0.002), ICU (P = 0.05), and hospital (P = 0.56) stay. Mortality was seen in 31 (2.7%) and 44 (11.9%) patients with and without AKI, respectively (P = 0.01). After multivariable logistic regression, there was an association between AKI and preoperative abnormal levels of creatinine (adjusted odds ratio [aOR] = 0.47, 95% confidence interval [CI] 0.22–1.01; P = 0.05), presence of cyanotic heart disease (aOR = 1.97, 95% CI = 1.15–3.2; P = 0.01), duration of surgery (aOR = 1.05/10 min, 95% CI = 1.01–1.08; P = 0.007), and elevated lactate level (aOR = 1.14, 95% CI = 1.03–1.3; P = 0.01).

Conclusion:

The presence of cyanotic heart disease, duration of surgery, elevated postoperative lactate level, and likely preoperative creatinine level were independent risk factors for the development of AKI after congenital heart surgery.

Acute Kidney Injury in Pediatric Heart Failure

Acute kidney injury (AKI) is very common in pediatric medical and surgical cardiac patients. Not only is it an independent risk factor for increased morbidity and mortality in the short run, but repeated episodes of AKI lead to chronic kidney disease (CKD) especially in the most vulnerable hosts with multiple risk factors, such as heart transplant recipients. The cardiorenal syndrome, a term coined to emphasize the bidirectional nature of simultaneous or sequential cardiac-renal dysfunction both in acute and chronic settings, has been recently described in adults but scarcely reported in children. Despite the common occurrence and clinical and financial impact, AKI in pediatric heart failure outside of cardiac surgery populations remains poorly studied and there are no large-scale pediatric specific preventive or therapeutic studies to date. This article will review pediatric aspects of the cardiorenal syndrome in terms of pathophysiology, clinical impact and treatment options.

Serum cystatin is a useful marker for the diagnosis of acute kidney injury in critically ill children: prospective cohort study

Background

Acute kidney injury (AKI) has been associated with high morbidity and mortality rates among critically ill children. Cystatin C is a protease inhibitor, and studies have shown that it is a promising marker for the early diagnosis of AKI. Our goal in this study was to assess whether serum cystatin C could serve as an accurate marker for the diagnosis of AKI.

Methods

This prospective study was undertaken in the pediatric intensive care unit at King Abdulaziz University Hospital. Serum creatinine and serum cystatin C levels were both measured in patients on admission (0 h) and at 6, 12, and 24 h after admission. AKI was diagnosed according to the modified pRIFLE criteria. Receiver operating characteristic (ROC) curve analysis was performed to assess the utility of serum cystatin C for diagnosing AKI.

Results

A total of 62 patients were enrolled in this study, and 32 were diagnosed with AKI according to the modified pRIFLE criteria (51.4 %). The area under the ROC curve for serum cystatin indicated that it was a good marker for the diagnosis of AKI at 0, 6, 12 and 24 h, with sensitivities of 78, 94, 94 and 83 %, respectively. However, the specificities of serum cystatin C at 0, 6, 12, and 24 h were 57, 57, 60 and 50 %, respectively. The optimal cutoff value was 0.645 mg/L. The area under the ROC for serum creatinine showed sensitivities of 50, 65.4, 69.2 and 57.7 % and specificities of 67.7, 70, 60 and 70 % at 0, 6, 12 and 24 h, respectively. The optimal cutoff value for serum creatinine was 30 μmol/l. Comparisons of ROC curves revealed that serum cystatin C was superior to serum creatinine for the diagnosis of AKI at 12 h (p = 0.03), but no differences were detected at 0, 6 or 24 h.

Conclusion

Serum cystatin is a sensitive, but not a specific, marker for the diagnosis of AKI in critically ill children.

Urinary NGAL-Positive Acute Kidney Injury and Poor Long-term Outcomes in Hospitalized Patients

Introduction

Neutrophil gelatinase−associated lipocalin (NGAL) is a widely studied biomarker of renal tubular injury. Urinary NGAL (uNGAL) during acute kidney injury (AKI) predicts short-term adverse outcomes. However, the long-term predictive value is unknown.

Methods

We performed a prospective observational study of 145 patients with hospital-acquired AKI according to Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) criteria and analyzed the long-term predictive value of uNGAL at the time of AKI. We defined a composite outcome of all-cause mortality and the development of end-stage renal disease (ESRD).

Results

In all, 61 AKI patients died and 22 developed ESRD within 6 months. The uNGAL levels were significantly higher in patients with poor long-term outcomes. uNGAL levels ≥362 μg/l (highest quartile) and uNGAL levels between 95 and 362 μg/l (third quartile) were associated with hazard ratios of 3.7 (95% confidence interval, 2.1–6.5) and 1.9 (1.1–3.5), respectively, compared with uNGAL levels <95 μg/l (lower quartiles). After 6 months, 67% and 43% of patients within the highest and third uNGAL quartile, respectively, had either progressed to ESRD or died, compared to only 21% of patients with uNGAL in the lower 2 quartiles (P < 0.001). In multivariable Cox regression analyses accounting for conventional predictors, uNGAL was the strongest independent predictor of adverse long-term outcomes. The association of uNGAL levels and poor long-term outcomes remained significant in the subgroup of 107 AKI survivors discharged without requiring dialysis (P = 0.002).

Discussion

These data indicate that elevated uNGAL levels at AKI diagnosis predict poor long-term outcomes.

PROGRESSION OF CHRONIC KIDNEY DISEASE AFTER ACUTE KIDNEY INJURY

The incidence of chronic kidney disease (CKD) in children and adults is increasing. Cardiologists have become indispensable members of the care provider team for children with CKD. This is partly due to the high incidence of CKD in children and adults with congenital heart disease, with current estimates of 30-50%. In addition, the high incidence of acute kidney injury (AKI) due to cardiac dysfunction or following pediatric cardiac surgery that may progress to CKD is also well documented. It is now apparent that AKI and CKD are uniquely intertwined as interconnected syndromes. Furthermore, the well-known long-term cardiovascular morbidity and mortality associated with CKD require the joint attention of both nephrologists and cardiologists. Children with both congenital heart disease and CKD are increasingly surviving to adulthood, with synergistically negative medical, financial, and quality of life impact. An improved understanding of the epidemiology, mechanisms, early diagnosis, and preventive measures is of importance to cardiologists, nephrologists, scientists, economists, and policy makers alike. Herein, we report the current definitions, epidemiology, and complications of CKD in children, with an emphasis on children with congenital heart disease. We then focus on the clinical and experimental evidence for the progression of CKD after episodes of AKI commonly encountered in children with heart disease, and explore the role of novel biomarkers for the prediction of CKD progression.

Early detection of acute kidney injury after pediatric cardiac surgery

Acute kidney injury (AKI) is increasingly recognized as a common problem in children undergoing cardiac surgery, with well documented increases in morbidity and mortality in both the short and the long term. Traditional approaches to the identification of AKI such as changes in serum creatinine have revealed a large incidence in this population with significant negative impact on clinical outcomes. However, the traditional diagnostic approaches to AKI diagnosis have inherent limitations that may lead to under-diagnosis of this pathologic process. There is a dearth of randomized controlled trials for the prevention and treatment of AKI associated with cardiac surgery, at least in part due to the paucity of early predictive biomarkers. Novel non-invasive biomarkers have ushered in a new era that allows for earlier detection of AKI. With these new diagnostic tools, a more consistent approach can be employed across centers that may facilitate a more accurate representation of the actual prevalence of AKI and more importantly, clinical investigation that may minimize the occurrence of AKI following pediatric cardiac surgery. A thoughtful management approach is necessary to mitigate the effects of AKI after cardiac surgery, which is best accomplished in close collaboration with pediatric nephrologists. Long-term surveillance for improvement in kidney function and potential development of chronic kidney disease should also be a part of the comprehensive management strategy.