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

The burden of innovation in the pediatric heart center

PURPOSE OF REVIEW

The purpose of this review is to elucidate the growing complexity involved in providing pediatric cardiac care in the contemporary era of innovation. Aiming to highlight the phenomenon of chronic critical illness in a pediatric heart center, this review outlines the burdens placed on those caring for these uniquely challenging patients and poses considerations for alleviating those burdens.

RECENT FINDINGS

As care advancements drive improved survival for children with heart disease, heart centers face a growing population of chronically critically ill patients with high resource utilization and uncertain trajectories. Preterm infants, single ventricles, and complex heart failure patients require significant interventions and expertise. Their lengthy courses challenge care delivery systems and resources, in addition to placing significant emotional and cognitive burdens on the multidisciplinary teams.

SUMMARY

The growing population of chronically critically ill cardiac patients are some of the most challenging both at the system level and on the team members. While undertaking innovative therapies, we must recognize that survival as an outcome cannot be separated from associated costs of achieving that outcome; the resultant burdens of innovation cannot be ignored. Heart centers must take a proactive stance in optimizing care for children with prolonged illness while also addressing the needs of those who care for them.

Acute Kidney Injury (AKI) After Pediatric Tonsillectomy: An Opportunity for Quality Improvement

PURPOSE

There is emerging evidence showing even a single episode of transient acute kidney injury (AKI) in children can have negative long-term health consequences. AKI may be under-recognized in children undergoing tonsillectomy because of unique risk factors, such as recommended use of NSAIDs and restricted oral intake pre- and postoperatively.

METHODS

A consecutive case series with chart review was performed for patients under age 18 years at a single tertiary care institution who underwent tonsillectomy between July 1, 2013 and May 17, 2024, identified by CPT codes for tonsillectomy. ED visits within 30 days of surgery were documented. Serum creatinine values at ED visit were recorded, if available, and incidence of elevated serum creatinine and AKI were determined.

RESULTS

Charts of 3018 pediatric tonsillectomy patients were reviewed. About 295 (9.8% of 3018) had an ED visit within 30 days for any reason, of whom 110 (37.3% of 295) had a serum creatinine value at this ED visit. Of these, 13 (11.8% of 110) had elevated serum creatinine, and 8 (7.3% of 110) had AKI by standardized criteria. One patient had a follow-up serum creatinine performed within 1 year which showed resolution of AKI.

CONCLUSION

Incidence of AKI following tonsillectomy has not been previously well recognized. Identification of previously unrecognized risks from post-tonsillectomy AKI represents an important potential area for quality improvement, including careful patient selection for use of non-steroidal anti-inflammatory drugs, close monitoring of those at higher risk for dehydration after surgery, and follow-up care for those diagnosed with AKI.

Framework for Kidney Health Follow-Up Among Neonates With Critical Cardiac Disease: A Report From the Neonatal Kidney Health Consensus Workshop

Acute kidney injury is common among neonates with critical cardiac disease. Risk factors and associations with kidney-related outcomes are heterogeneous and distinct from other neonates. As survival of children with critical cardiac disease increases to adulthood, the burden of chronic kidney disease is increasing. Thirty percent to 50% of adults with congenital heart disease have impaired kidney function, even in the absence of prior kidney injury episodes. This may be related to the current standardized acute kidney injury criteria, which may not fully capture clinically meaningful kidney injury and long-term kidney health risks. An improved understanding of which neonates with critical cardiac disease should undergo kidney health follow-up is imperative. During the National Institutes of Health-supported Neonatal Kidney Health Consensus Workshop to Address Kidney Health meeting conducted in February 2024, a panel of 51 neonatal nephrology experts focused on at-risk groups: (1) preterm infants, (2) critically ill infants with acute kidney injury, and (3) infants with critical cardiac disease. The critical cardiac disease subgroup, comprising multidisciplinary experts, used a modified Delphi process to achieve consensus on recommendations for kidney health follow-up. In this report, we review available data on kidney health follow-up in critical cardiac disease and summarize the 2 consensus-based recommendations. We introduce novel diagnostic and risk-stratification tools for acute kidney injury diagnosis in neonates with cardiac disease to guide follow-up recommendations. Finally, we identify important knowledge gaps, representing areas of focus for future research. These should be prioritized to understand and improve long-term kidney health in critical cardiac disease.

Pediatric Considerations in Post Acute Kidney Injury Care

Acute kidney injury in children is associated with adverse outcomes. These include longer hospital stays, increased mortality, and nonrecovery of kidney function in the short term and increased health care utilization, new onset hypertension, and chronic kidney disease in the long term. Systematic post acute kidney injury care may help mitigate some of the complications that follow acute kidney injury. Patient, family, and health care team education is a key aspect of post acute kidney injury care. This includes individualized education to the patient and family, ideally prior to hospital discharge, provision of a discharge summary with details of the acute kidney injury episode and follow-up plan, and communication with the primary care provider. Given that severe acute kidney injury may often be seen in patients with other underlying medical conditions, partnership between the primary care provider, non-nephrology specialist and the nephrologist, and the use of telehealth may facilitate follow-up without increasing caregiver burden. Ongoing surveillance includes monitoring kidney function, proteinuria, and hypertension. There are no guidelines on the frequency of this evaluation or the duration of follow-up. These decisions should be individualized based on the characteristics of the index acute kidney injury episode and underlying risk factors for chronic kidney disease.

Relationship between intra-operative urine output and postoperative acute kidney injury in paediatric cardiac surgery: A retrospective observational study

BACKGROUND

Intra-operative urine output (UO) has been shown to predict postoperative acute kidney injury (AKI) in adults; however, its significance in children undergoing cardiac surgery remains unknown.

OBJECTIVE

To explore the association between intra-operative UO and postoperative AKI in children with congenital heart disease.

DESIGN

A retrospective observational study.

SETTING

A tertiary hospital.

PATIENTS

Children aged >28 days and <6 years who underwent cardiac surgery at Fuwai Hospital from 1 April 2022 to 30 August 2022.

MAIN OUTCOME MEASURES

AKI was identified by the highest serum creatinine value within postoperative 7 days using Kidney Disease Improving Global Outcomes (KDIGO) criteria.

RESULTS

In total, 1184 children were included. The incidence of AKI was 23.1% (273/1184), of which 17.7% (209/1184) were stage 1, 4.2% (50/1184) were stage 2, and others were stage 3 (1.2%, 14/1184). Intra-operative UO was calculated by dividing the total intra-operative urine volume by the duration of surgery and the actual body weight measured before surgery. There was no significant difference in median [IQR] intra-operative UO between the AKI and non-AKI groups (2.6 [1.4 to 5.4] and 2.7 [1.4 to 4.9], respectively, P  = 0.791), and multivariate logistic regression analyses showed that intra-operative UO was not associated with postoperative AKI [adjusted odds ratio (OR) 0.971; 95% confidence interval (CI), 0.930 to 1.014; P  = 0.182]. Regarding the clinical importance of severe forms of AKI, we further explored the association between intra-operative UO and postoperative moderate-to-severe AKI (adjusted OR 0.914; 95% CI, 0.838 to 0.998; P  = 0.046).

CONCLUSIONS

Intra-operative UO was not associated with postoperative AKI during paediatric cardiac surgery. However, we found a significant association between UO and postoperative moderate-to-severe AKI. This suggests that reductions in intra-operative urine output below a specific threshold may be associated with postoperative renal dysfunction.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT05489263.

Long-Term Kidney Outcomes after Pediatric Acute Kidney Injury

Key Points

Among 4173 children with AKI, 18% had major adverse kidney events (death, kidney failure, or CKD) during a median 10-year follow-up. AKI survivors were at 2–4 times higher risk of major adverse kidney events, hypertension, and subsequent AKI versus matched hospitalized comparators. This justifies improved surveillance after pediatric AKI to detect CKD and hypertension early and improve long-term kidney health.

Background

AKI is common in hospitalized children. Pediatric AKI receiving acute KRT is associated with long-term CKD, hypertension, and death. We aim to determine the outcomes after AKI in children who did not receive acute KRT because these remain uncertain.

Methods

Retrospective cohort study of all hospitalized children (0–18 years) surviving AKI without acute KRT between 1996 and 2020 in Ontario, Canada, identified by validated diagnostic codes in provincial administrative health databases. Children with prior KRT, CKD, or AKI were excluded. Cases were matched with up to four hospitalized comparators without AKI by age, neonatal status, sex, intensive care unit admission, cardiac surgery, malignancy, hypertension, hospitalization era, and a propensity score for AKI. Patients were followed until death, provincial emigration, or censoring in March 2021. The primary outcome was long-term major adverse kidney events (a composite of all-cause mortality, long-term KRT, or incident CKD).

Results

We matched 4173 pediatric AKI survivors with 16,337 hospitalized comparators. Baseline covariates were well-balanced following propensity score matching. During a median 9.7-year follow-up, 18% of AKI survivors developed long-term major adverse kidney event versus 5% of hospitalized comparators (hazard ratio [HR], 4.0; 95% confidence interval [CI], 3.6 to 4.4). AKI survivors had higher rates of long-term KRT (2% versus <1%; HR, 11.7; 95% CI, 7.5 to 18.4), incident CKD (16% versus 2%; HR, 7.9; 95% CI, 6.9 to 9.1), incident hypertension (17% versus 8%; HR, 2.3; 95% CI, 2.1 to 2.6), and AKI during subsequent hospitalization (6% versus 2%; HR, 3.7; 95% CI, 3.1 to 4.5), but no difference in all-cause mortality (3% versus 3%; HR, 0.9; 95% CI, 0.7 to 1.1).

Conclusions

Children surviving AKI without acute KRT were at higher long-term risk of CKD, long-term KRT, hypertension, and subsequent AKI versus hospitalized comparators.

Risk of acute kidney injury after lower urinary tract reconstruction with early NSAID therapy: A propensity matched retrospective analysis

INTRODUCTION

The opioid epidemic response led to increased use of postoperative, non-opioid analgesia. Some pediatric urologists do not routinely use non-steroidal anti-inflammatory drugs (NSAIDs) for fear of causing acute kidney injury (AKI). While previous studies have demonstrated the safety and efficacy of NSAIDs in children, safety after lower urinary tract reconstruction has not been well characterized.

OBJECTIVE

ptUsing the Kidney Disease: Improving Global Outcomes (KDIGO) criteria for AKI (increase in creatinine ≥0.3 mg/dL or increase in creatinine ≥1.5x baseline or urine output <0.5 mL/kg/hr for 6 h), we hypothesized there would be a difference in the incidence of postoperative AKI between patients who did and did not receive NSAIDs following surgery.

STUDY DESIGN

Patients 2-18 years old who underwent lower urinary tract reconstruction (i.e., bladder augmentation and/or creation of a catheterizable channel) from 2009 to 2021 and had documented urine output were retrospectively reviewed. Chronic kidney disease (CKD) stage was calculated from creatinine and cystatin C within 6 months of surgery using the CKiD U25 equations. Patients who received NSAIDs were propensity matched on 11 characteristics with patients undergoing similar surgeries who did not receive NSAIDs. The primary outcome was incidence of AKI within 48 h of surgery.

RESULTS

The unmatched cohorts included 243 patients. Propensity matching identified 166 patients in the NSAID arm and 41 in the no NSAID arm. 26 patients with CKD stage 2-3 were included. There was no significant difference in the incidence of postoperative AKI based on any KDIGO criteria (17.1% no NSAID versus 16.3% NSAID, p = 0.87). Median postoperative opioids fell from 0.88 mg/kg in the no NSAID arm to 0.37 mg/kg morphine equivalents in the NSAID arm, although this was not statistically significant. Log-rank testing by Kaplan-Meier analysis demonstrated no difference in time to incidence of low urine output between the groups (p = 0.32). In the whole population not stratified by NSAID use, no differences were seen in AKI between those with and without CKD (16.7% with versus 17.9% without CKD).

DISCUSSION

There was no difference in the incidence of postoperative AKI among patients who did and did not receive NSAIDs after lower urinary tract reconstruction, excluding those with advanced CKD.

CONCLUSION

These results support that postoperative NSAIDs were an unlikely source of AKI. However, AKI remained a risk following these surgeries, regardless of NSAID use, likely owing to underlying disease, longer operations, and fluid shifts.

Prediction of Acute Kidney Injury After Coronary Artery Bypass Graft From Preoperative Serum Uric Acid

OBJECTIVE

To examine the association of an elevated level of uric acid (UA) in the bloodstream with an increased likelihood of acute kidney injury (AKI) following coronary artery bypass grafting (CABG) surgery.

DESIGN

Retrospective cohort study using a multivariate logistic regression model.

SETTING

Single institution.

PARTICIPANTS

Recipients of CABG surgery.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

A total of 761 individuals who underwent CABG were included in the study. The participants were categorized into 4 groups based on their UA level: Q1 group (UA <292.5 μmol/L), Q2 group (292.5 ≤ UA <353 μmol/L), Q3 group (353 ≤ UA < 423 μmol/L), and Q4 group (UA ≥423 μmol/L). A total of 167 patients, accounting for 21.9% of the sample, experienced postoperative AKI. The study found a significantly higher risk of AKI in the Q4 group compared to the Q1 group (40.4% v 8.9%; p < 0.001). After adjustment for confounding variables, an independent association between serum UA concentration and an elevated risk of AKI post-CABG was identified (odds ratio, 6.41; 95% confidence interval, 3.49-12.32; p < 0.001; p for trend < 0.001).

CONCLUSIONS

There is a relationship between preoperative blood UA level and the occurrence of AKI following CABG surgery.

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.

Selected 2022 Highlights in Congenital Cardiac Anesthesia

This article is a review of the highlights of pertinent literature of interest to the congenital cardiac anesthesiologist, and was published in 2022. After a search of the United States National Library of Medicine PubMed database, several topics emerged in which significant contributions were made in 2022. The authors of this manuscript considered the following topics noteworthy to be included in this review-intensive care unit admission after congenital cardiac catheterization interventions, antifibrinolytics in pediatric cardiac surgery, the current status of the pediatric cardiac anesthesia workforce in the United States, and kidney injury and renal protection during congenital heart surgery.