Neutrophil gelatinase-associated lipocalin reflects inflammation and is not a reliable renal biomarker in neonates and infants after cardiopulmonary bypass: a prospective case-control study

Gut microbiota and neonatal acute kidney injury biomarkers

One of the most frequent issues in newborns is acute kidney injury (AKI), which can lengthen their hospital stay or potentially raise their chance of dying. The gut-kidney axis establishes a bidirectional interplay between gut microbiota and kidney illness, particularly AKI, and demonstrates the importance of gut microbiota to host health. Since the ability to predict neonatal AKI using blood creatinine and urine output as evaluation parameters is somewhat constrained, a number of interesting biomarkers have been developed. There are few in-depth studies on the relationships between these neonatal AKI indicators and gut microbiota. In order to gain fresh insights into the gut-kidney axis of neonatal AKI, this review is based on the gut-kidney axis and describes relationships between gut microbiota and neonatal AKI biomarkers.

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.

Acute kidney injury in pediatrics: an overview focusing on pathophysiology

Acute kidney injury (AKI) is defined as an abrupt decline in glomerular filtration rate, with increased serum creatinine and nitrogenous waste products due to several possible etiologies. Incidence in the pediatric population is estimated to be 3.9 per 1,000 hospitalizations, and prevalence among children admitted to intensive care units is 26.9%. Despite being a condition with important incidence and morbimortality, further evidence on pathophysiology and management among the pediatric population is still lacking. This narrative review aimed to summarize and discuss current data on AKI pathophysiology in the pediatric population, considering all the physiological particularities of this age range and common etiologies. Additionally, we reported current diagnostic tools, novel biomarkers, and newly proposed medications that have been studied with the aim of early diagnosis and appropriate treatment of AKI in the future.

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.

Neutrophil gelatinase associated lipocalin in predicting postoperative acute kidney injury in elderly

BACKGROUND

Elderly patients are at increased risk of developing acute kidney injury (AKI) following major surgery and rapid diagnosis is essential.

AIM

This study aimed to examine the potential utility of plasma neutrophil gelatinase associated lipocalin levels in early prediction of AKI in geriatric patients undergoing laparotomic oncological surgery.

METHODS

This prospective single-center cohort study included 60 geriatric patients (≥ 65 years of age) that underwent major oncologic surgery with laparotomy. Perioperative measurements of plasma creatinine, blood urinary nitrogen, plasma lactate, urine output, and neutrophil gelatinase associated lipocalin (NGAL) were made. Patients were followed for AKI development, which is the primary outcome measure, and predictive role of NGAL was investigated.

RESULTS

At 48 h follow-up, AKI developed in 13 patients (21.7%). Significant differences in creatinine (p < 0.001), NGAL (p < 0.001), and urine output levels (p = 0.001) were evident over time between the two groups. High NGAL measurements at 6 and 24 h after surgery seem to be highly predictive of AKI development. At 6 h, a plasma NGAL level greater than 71.8 ng/mL has a sensitivity and specificity of 85% and 81% in predicting subsequent AKI development.

CONCLUSIONS

Plasma NGAL levels seem to represent an early and reliable marker for AKI in elderly patients undergoing laparotomic surgery with the potential to allow early diagnosis and prevent further renal deterioration. Further confirmatory studies are warranted.

TRIAL REGISTRATION

The study was registered to ClinicalTrials.gov (number, NCT05030727).

IMPLICATION STATEMENT

Elderly patients are at increased risk of postoperative acute kidney injury (AKI). This study shows that plasma neutrophil gelatinase associated lipocalin is a helpful marker to predict AKI in elderly patients undergoing laparotomic major surgery, which will allow early diagnosis and prevent further renal deterioration in this vulnerable patient group.

Early prediction of acute kidney injury in neonates with cardiac surgery

Background

Acute kidney injury (AKI) occurs in 42%–64% of the neonatal patients experiencing cardiac surgery, contributing to postoperative morbidity and mortality. Current diagnostic criteria, which are mainly based on serum creatinine and hourly urine output, are not sufficiently sensitive and precise to diagnose neonatal AKI promptly. The purpose of this review is to screen the recent literature, to summarize the novel and cost-effective biomarkers and approaches for neonatal AKI after cardiac surgery (CS-AKI), and to provide a possible research direction for future work.

Data sources

We searched PubMed for articles published before November 2019 with pertinent terms. Sixty-seven articles were found and screened. After excluding 48 records, 19 articles were enrolled for final analysis.

Results

Nineteen articles were enrolled, and 18 possible urinary biomarkers were identified and evaluated for their ability to diagnose CS-AKI. Urinary neutrophil gelatinase-associated lipocalin (uNGAL), serum cystatin C (sCys), urinary human kidney injury molecule-1 (uKIM-1), urinary liver fatty acid-binding protein (uL-FABP) and interleukin-18 (uIL-18) were the most frequently described as the early predictors of neonatal CS-AKI.

Conclusions

Neonates are vulnerable to CS-AKI. UNGAL, sCys, uL-FABP, uKIM-1 and uIL-18 are potential biomarkers for early prediction of neonatal CS-AKI. Renal regional oxygen saturation by near-infrared spectroscopy is a non-invasive approach for early identification of neonatal AKI. Further work should focus on exploring a sensitive and specific combined diagnostic model that includes novel biomarkers and other complementary methods.

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.

The Effect of Levosimendan Versus Milrinone on the Occurrence Rate of Acute Kidney Injury Following Congenital Heart Surgery in Infants: A Randomized Clinical Trial

OBJECTIVES

It has been shown that, in contrast to other inotropic agents, levosimendan improves glomerular filtration rate after adult cardiac surgery. The aim of this study was to investigate the efficacy of levosimendan, compared with milrinone, in preventing acute kidney dysfunction in infants after open-heart surgery with cardiopulmonary bypass.

DESIGN

Two-center, double-blinded, prospective, randomized clinical trial.

SETTING

The study was performed in two tertiary pediatric centers, one in Sweden (Gothenburg) and one in Finland (Helsinki).

PATIENTS

Infants between 1 and 12 months old, diagnosed with Tetralogy of Fallot, complete atrioventricular septal defect or nonrestrictive ventricular septal defect, undergoing total corrective cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

Seventy-two infants were randomized to receive a perioperative infusion of levosimendan (0.1 µg/kg/min) or milrinone (0.4 µg/kg/min). The infusion was initiated at the start of cardiopulmonary bypass and continued for 26 hours.

MEASUREMENTS AND MAIN RESULTS

The primary outcome variable was the absolute value of serum creatinine data on postoperative day 1. Secondary outcomes included the following: 1) acute kidney injury according to the serum creatinine criteria of the Kidney Diseases: Improving Global Outcomes; 2) acute kidney injury with serum creatinine corrected for fluid balance; 3) plasma neutrophil gelatinase-associated lipocalin; 4) cystatin C; 5) urea; 6) lactate; 7) hemodynamic variables; 8) use of diuretics in the PICU; 9) need of dialysis; 10) length of ventilator therapy; and 11) length of PICU stays. There was no significant difference in postoperative serum creatinine between the treatment groups over time (p = 0.65). The occurrence rate of acute kidney injury within 48 hours was 46.9% in the levosimendan group and 39.5% in the milrinone group (p = 0.70). There were no significant differences in other secondary outcome variables between the groups.

CONCLUSIONS

Levosimendan compared with milrinone did not reduce the occurrence rate of acute kidney injury in infants after total corrective heart surgery for atrioventricular septal defect, ventricular septal defect, or Tetralogy of Fallot.

The Relationship Between Neutrophil to Lymphocyte Ratio and Clinical Outcome in Pediatric Patients After Cardiopulmonary Bypass Surgery: A Retrospective Study

Background: The aim of this study was to investigate the prognostic role of the neutrophil to lymphocyte ratio (NLR) in pediatric patients undergoing open-heart surgery with cardiopulmonary bypass (CPB). Methods: A retrospective cohort study of 61 pediatric patients who underwent CPB in the First Affiliated Hospital of Nanjing Medical University from January 2017 to October 2018 was conducted. All perioperative clinical data, including neutrophil count, lymphocyte count, and C-reactive protein (CRP), were collected retrospectively. The prognostic value of NLR and its association with extubation time, duration of intensive care unit (ICU) stay and in-hospital stay were analyzed. Results: Neutrophil count, NLR, and CRP were significantly increased post-operative compared with pre-operative (p < 0.05). The increased post-operative levels of NLR were significantly associated with longer extubation time, as well as prolonged post-operative cardiac ICU stay (p < 0.05). Multivariate linear regression analysis revealed that elevated NLR displayed a significant independent association with extubation time and the duration of an ICU stay. Conclusion: Increased post-operative NLR followed by cardiac surgery with CPB in pediatric patients was associated with longer extubation time and a longer duration of an ICU stay.