Subphenotypes of acute kidney injury in children

Diuretic response after neonatal cardiac surgery: a report from the NEPHRON collaborative

BACKGROUND

Multicenter early diuretic response (DR) analysis of single furosemide dosing following neonatal cardiac surgery is lacking to inform whether early DR predicts adverse clinical outcomes.

METHODS

We performed a retrospective cohort study utilizing data from the NEPHRON registry. Random forest machine learning generated receiver operating characteristic-area under the curve (ROC-AUC) and odds ratios for mechanical ventilation (MV) and respiratory support (RS). Prolonged MV and RS were defined using ≥ 90th percentile of observed/expected ratios. Secondary outcomes were prolonged CICU and hospital length of stay (LOS) and kidney failure (stage III acute kidney injury (AKI), peritoneal dialysis, and/or continuous kidney replacement therapy on postoperative day three) assessed using covariate-adjusted ROC-AUC curves.

RESULTS

A total of 782 children were included. Cumulative urine output (UOP) metrics were lower in prolonged MV and RS patients, but DR poorly predicted prolonged MV (highest AUC 0.611, OR 0.98, sensitivity 0.67, specificity 0.53, p = 0.006, 95% OR CI 0.96-0.99 for cumulative 6-h UOP) and RS (highest AUC 0.674, OR 0.94, sensitivity 0.75, specificity 0.54, p < 0.001, 95% CI 0.91-0.97 UOP between 3 and 6 h). Secondary outcome results were similar. DR had fair discrimination for kidney failure (AUC 0.703, OR 0.94, sensitivity 0.63, specificity 0.71, 95% OR CI 0.91-0.98, p < 0.001, cumulative 6-h UOP).

CONCLUSIONS

Early DR poorly discriminated patients with prolonged MV, RS, and LOS in this cohort, though it may identify severe postoperative AKI phenotype. Future work is warranted to determine if early DR or late postoperative DR later, in combination with other AKI metrics, may identify a higher-risk phenotype.

Daily serum phosphate increase as early and reliable indicator of kidney injury in children with leukemia and lymphoma developing tumor lysis syndrome

BACKGROUND

Tumor lysis syndrome (TLS) and its most serious complication, acute kidney injury (AKI) are one of the emergency conditions in onco-hematology. It is difficult to predict the degree of kidney involvement. Therefore, we studied children with leukemia and lymphoma treated in four Hungarian tertiary centers (inpatient university clinics) retrospectively (2006-2016) from a nephrological aspect.

METHOD

Data of 31 pediatric patients were obtained from electronic- and paper-based medical records. Physical status, laboratory test results, treatments, and outcomes were assessed. Patients were analyzed according to both "traditional" TLS groupings, as laboratory TLS or clinical TLS, and nephrological aspect based on pRIFLE classification, as mild or severe AKI.

RESULTS

Significant differences were found between the changes in parameters of phosphate homeostasis and urea levels in both classifications. Compared to age-specific normal phosphate ranges, before the development of TLS, hypophosphatemia was common (19/31 cases), while in the post-TLS period, hyperphosphatemia was observed (26/31 cases) most frequently. The rate of daily change in serum phosphate level was significant in the nephrological subgroups, but peaks of serum phosphate level show only a moderate increase. The calculated cut-off value of daily serum phosphate level increased before AKI was 0.32 mmol/L per ROC analysis for severe TLS-AKI. The 24-h urinalysis data of eight patients revealed transiently increased phosphate excretion only in those patients with TLS in whom serum phosphate was elevated in parallel.

CONCLUSION

Daily serum phosphate level increase can serve as a prognostic factor for the severity of pediatric TLS, as well as predict the severity of kidney involvement. A higher resolution version of the Graphical abstract is available as Supplementary information.

Subphenotypes of Pediatric Acute Kidney Injury

Acute kidney injury (AKI) is seen frequently in hospitalized patients and is associated with increased risk of mortality and adverse short- and long-term renal and systemic complications. Emerging data suggest that AKI is a heterogenous syndrome with a variety of underlying causes, predisposing illnesses, and range of clinical trajectories and outcomes. This mini-review aims to discuss emerging AKI subphenotype classifications as our understanding of the heterogeneity and underlying pathophysiology has improved.

Association of Urine Biomarkers With Acute Kidney Injury and Fluid Overload in Infants After Cardiac Surgery: A Single Center Ancillary Cohort of the Steroids to Reduce Systemic Inflammation After Infant Heart Surgery Trial

To examine the association between three perioperative urine biomarker concentrations (urine cystatin C [uCysC], urine neutrophil gelatinase-associated lipocalin [uNGAL], and urine kidney injury molecule 1 [uKIM-1]), and cardiac surgery-associated acute kidney injury (CS-AKI) and fluid overload (FO) in infants with congenital heart disease undergoing surgery on cardiopulmonary bypass. To explore how urine biomarkers are associated with distinct CS-AKI phenotypes based on FO status.

DESIGN

Ancillary prospective cohort study.

SETTING

Single U.S. pediatric cardiac ICU.

PATIENTS

Infants less than 1 year old enrolled in the Steroids to Reduce Systemic Inflammation after Infant Heart Surgery trial (NCT03229538) who underwent heart surgery from June 2019 to May 2020 and opted into biomarker collection at a single center. Infants with preoperative CS-AKI were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Forty infants met inclusion criteria. Median (interquartile) age at surgery was 103 days (5.5-161 d). Modified Kidney Disease Improving Global Outcomes-defined CS-AKI was diagnosed in 22 (55%) infants and 21 (53%) developed FO. UCysC and uNGAL peaked in the early postoperative period and uKIM-1 peaked later. In unadjusted analysis, bypass time was longer, and Vasoactive-Inotropic Score at 24 hours was higher in infants with CS-AKI. On multivariable analysis, higher uCysC (odds ratio [OR], 1.023; 95% CI, 1.004-1.042) and uNGAL (OR, 1.019; 95% CI, 1.004-1.035) at 0-8 hours post-bypass were associated with FO. UCysC, uNGAL, and uKIM-1 did not significantly correlate with CS-AKI. In exploratory analyses of CS-AKI phenotypes, uCysC and uNGAL were highest in CS-AKI+/FO+ infants.

CONCLUSIONS

In this study, uCysC and uNGAL in the early postoperative period were associated with FO at 48 hours. UCysC, uNGAL, and uKIM-1 were not associated with CS-AKI. Further studies should focus on defining expected concentrations of these biomarkers, exploring CS-AKI phenotypes and outcomes, and establishing clinically meaningful endpoints for infants post-cardiac 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.

Neonatal AKI: An update

Neonatal acute kidney injury (AKI) is a common complication, especially in the neonatal intensive care unit, that is associated with long term consequences and poor outcomes. Early detection and treatment is critical. Currently, neonatal AKI is defined with urinary markers and serum creatinine, with limitations on early detection and individual treatment. There have been numerous biomarkers and risk factor scores that have been studied for their ability to predict neonatal AKI. To move towards personalized medicine, neonatal AKI must be categorized into phenotypes and subphenotypes that fully encapsulate the diverse causes and specific treatments. This review aims to advance our understanding of neonatal AKI detection through the use of biomarkers, subphenotypes, and phenotypes to move towards personalized treatment strategies.