Neonatal Acute Kidney Injury

Metabolomic profiling demonstrates evidence for kidney and urine metabolic dysregulation in a piglet model of cardiac surgery-induced acute kidney injury

Acute kidney injury (AKI) is a common cause of morbidity after congenital heart disease surgery. Progress on diagnosis and therapy remains limited, however, in part due to poor mechanistic understanding and a lack of relevant translational models. Metabolomic approaches could help identify novel mechanisms of injury and potential therapeutic targets. In the present study, we used a piglet model of cardiopulmonary bypass with deep hypothermic circulatory arrest (CPB/DHCA) and targeted metabolic profiling of kidney tissue, urine, and serum to evaluate metabolic changes specific to animals with histological acute kidney injury. CPB/DHCA animals with acute kidney injury were compared with those without acute kidney injury and mechanically ventilated controls. Acute kidney injury occurred in 10 of 20 CPB/DHCA animals 4 h after CPB/DHCA and 0 of 7 control animals. Injured kidneys showed a distinct tissue metabolic profile compared with uninjured kidneys (R² = 0.93, Q² = 0.53), with evidence of dysregulated tryptophan and purine metabolism. Nine urine metabolites differed significantly in animals with acute kidney injury with a pattern suggestive of increased aerobic glycolysis. Dysregulated metabolites in kidney tissue and urine did not overlap. CPB/DHCA strongly affected the serum metabolic profile, with only one metabolite that differed significantly with acute kidney injury (pyroglutamic acid, a marker of oxidative stress). In conclusion, based on these findings, kidney tryptophan and purine metabolism are candidates for further mechanistic and therapeutic investigation. Urine biomarkers of aerobic glycolysis could help diagnose early acute kidney injury after CPB/DHCA and warrant further evaluation. The serum metabolites measured at this early time point did not strongly differentiate based on acute kidney injury.

NEW & NOTEWORTHY This project explored the metabolic underpinnings of postoperative acute kidney injury (AKI) following pediatric cardiac surgery in a translationally relevant large animal model of cardiopulmonary bypass with deep hypothermic circulatory arrest. Here, we present novel evidence for dysregulated tryptophan catabolism and purine catabolism in kidney tissue and increased urinary glycolysis intermediates in animals who developed histological AKI. These pathways represent potential diagnostic and therapeutic targets for postoperative AKI in this high-risk population.

Improving acute kidney injury diagnostic precision using biomarkers

Acute kidney injury (AKI) is common in hospitalized patients of all ages and is associated with significant morbidity and mortality. Accurate prediction and early identification of AKI is of utmost importance because no therapy exists to mitigate AKI once it has occurred. Yet, serum creatinine lacks adequate sensitivity and specificity, and quantification of urine output is challenging in incontinent children without indwelling bladder catheters. Integration of clinically available biomarkers have the potential to delineate unique AKI phenotypes that could have important prognostic and therapeutic implications. Plasma Cystatin C, urine neutrophil gelatinase associated lipocalin (NGAL) and the urinary product of tissue inhibitor metalloproteinase (TIMP-2) and insulin growth factor binding protein-7 (IGFBP7) are clinically available. These biomarkers have been studied in heterogenous populations across the age spectrum and in a variety of clinical settings for prediction of AKI. The purpose of this review is to describe and discuss the clinically available AKI biomarkers including how they have been used to delineate AKI phenotypes.

Incidence, Risk Factors, and Outcomes of Acute Kidney Injury in Necrotizing Enterocolitis: A Prospective Single-Center Study

Necrotizing enterocolitis (NEC) is a significant cause of morbidity and mortality in the neonatal intensive care unit (NICU). Acute kidney injury (AKI) is considered to be one of the most well-established risk factors for mortality in neonates. The aim of this work was to study the incidence of AKI in neonates with NEC and to determine the associated conditions, risk factors, and outcomes. We carried out this prospective cross-sectional study on 104 neonates treated for NEC from September 2015 to September 2019. Diagnoses of AKI were made using the neonatal modified Kidney Disease: Improved Global Outcome criteria. AKI occurred in 63 neonates (61%), with 32 at Stage 1 (31%), 20 at Stage 2 (19%), and 11 at Stage 3 (11%), including three requiring dialysis. Vancomycin use and positive blood culture were risk factors for developing AKI in our NEC neonates (odds ratio: 2.47 and 2.41; P = 0.03 and 0.04, respectively). Neonates with AKI had a higher mortality rate (47.6% vs. 26.8 %, P = 0.03) and an increased length of stay (LOS) (69.8 days vs. 53.9 days, P <0.01) than the non-AKI group. Surgical intervention was required in 11 (10.5%) of our neonates. We concluded that AKI occurs in about 60% of neonates with NEC and is associated with higher mortality and LOS in the NICU. Therefore, it is very important to identify and manage all neonates who are at a high risk of developing AKI as quickly as possible.

Evaluation of acute kidney injury after surgery for congenital heart disease in neonates: a tertiary hospital experience

PURPOSE OF THE ARTICLE

Acute kidney injury (AKI) after cardiac surgery in children with congenital heart disease (CHD) is a serious complication closely associated with high morbidity and mortality. Despite numerous studies on AKI in children, most studies have excluded neonates. We sought to characterize AKI associated with cardiac surgery in neonates, determine its incidence, perioperative and postoperative risk factors, and short-term results.

MATERIALS AND METHODS

This retrospective study included 177 neonates who were operated on for CHD in our hospital between January 2015 and December 2019. Data of the patients were analyzed according to nKDIGO (neonatal Kidney Disease Improving Global Outcomes) and nRIFLE (neonatal Risk, Injury, Failure, Loss of function, End-stage kidney disease) criteria for evaluating AKI retrospectively. Data of groups with and without AKI were analyzed.

RESULTS

The average age of 177 neonates were 8.2 ± 6.1 (1-28) days. Twenty-two (12.4%) neonates had CS-AKI defined according to nKDIGO criteria. Four (2.3%) neonates reached nKDIGO stage I, 1 (0.6%) reached stage II, 17 (9.6%) reached stage III. Thirty-eight (21.5%) neonates had CS-AKI defined according to nRIFLE criteria. Twenty-four (13.6%) neonates reached nRIFLE stage risk(R), 6 (3.4%) reached stage injury(I), 8 (4.5%) reached stage failure (F). The incidence of cardiac surgery-associated acute kidney injury (CS-AKI) in neonates was 12.5% and 21.5% for nKDIGO and nRIFLE, respectively. The percentage difference between nKDIGO and nRIFLE for AKI assessment was due to the criteria for nRIFLE stage risk(R) urine output < 1.5 mL/kg/h for 24 h. In both classifications, the duration of cardiopulmonary bypass, operation, inotropic treatment, and mechanical ventilation, length of intensive care unit (ICU), and hospital stay were significantly higher in the AKI group than those without AKI group (p˂.05). The mortality rate in the groups with AKI was found to be significantly higher (p˂.05) than in the groups without AKI. In Kappa analysis, when two classifications were compared according to AKI stages, a significant agreement was found between nKDIGO and nRIFLE classifications (p˂.05) (Kappa: 0.299).

CONCLUSION

AKI and mortality rates were similar between groups according to the nKDIGO and nRIFLE criteria. For early prediction of AKI and adverse outcomes, diagnostic reference intervals might be specified in more detail in neonates undergoing cardiac surgery for CHD.

Transient and persistent acute kidney injury phenotypes following the Norwood operation: a retrospective study

BACKGROUND

Acute kidney injury is a common complication following the Norwood operation. Most neonatal studies report acute kidney injury peaking within the first 48 hours after cardiac surgery. The aim of this study was to evaluate if persistent acute kidney injury (>48 postoperative hours) after the Norwood operation was associated with clinically relevant outcomes.

METHODS

Two-centre retrospective study among neonates undergoing the Norwood operation. Acute kidney injury was initially identified as developing within the first 48 hours after cardiac surgery and stratified into transient (≤48 hours) and persistent (>48 hours) using the neonatal modification of the Kidney Disease: Improving Global Outcomes serum creatinine criteria. Severe was defined as stage ≥2. Primary and secondary outcomes were mortality and duration of ventilation and hospital length of stay.

RESULTS

One hundred sixty-eight patients were included. Transient and persistent acute kidney injuries occurred in 24 and 17%, respectively. Cardiopulmonary bypass and aortic cross clamp duration, and incidence of cardiac arrest were greater among those with persistent kidney injury. Mortality was four times higher (41 versus 12%, p < 0.001) and mechanical ventilation duration 50 hours longer in persistent acute kidney injury patients (158 versus 107 hours; p < 0.001). In multivariable analysis, persistent acute kidney injury was not associated with mortality, duration of ventilation or length of stay. Severe persistent acute kidney injury was associated with a 59% increase in expected ventilation duration (aIRR:1.59, 95% CI:1.16, 2.18; p = 0.004).

CONCLUSIONS

Future large studies are needed to determine if risk factors and outcomes change by delineating acute kidney injury into discrete timing phenotypes.

Brain injury in preterm infants with surgical necrotizing enterocolitis: clinical and bowel pathological correlates

BACKGROUND

The objective of this study was to determine the risk factors and outcomes of white matter brain injury (WMBI) on magnetic resonance imaging (MRI) at term-equivalent age in infants with surgical necrotizing enterocolitis (NEC).

METHODS

This retrospective study compared clinical/pathological information between infants with and those without WMBI.

RESULTS

Out of 69 infants with surgical NEC, 17 (24.6%) had mild WMBI, 13 (18.8%) had moderate WMBI, and six (8.7%) had severe WMBI on the brain MRI. Several clinical factors (gestational age, more red blood cell (RBC) transfusions before NEC onset, pneumoperitoneum, earlier NEC onset age, postoperative ileus, acute kidney injury (AKI) by serum creatinine, postnatal steroids, hospital stay) and histopathological findings (necrosis, hemorrhage) had univariate associations with WMBI. Associations with RBC transfusion (odds ratio (OR) 23.6 [95% confidence interval (CI): 4.73-117.97]; p = 0.0001), age at NEC onset (OR 0.30 [95%CI: 0.11-0.84]; p = 0.021), necrosis (OR 0.10 [95%CI: 0.01-0.90]; p = 0.040), and bowel hemorrhage (OR 7.79 [95%CI: 2.19-27.72]; p = 0.002) persisted in multivariable association with grade 3-4 WMBI. The infants with WMBI had lower mean motor, cognitive, language scores, and higher ophthalmic morbidity at 2 years of age.

CONCLUSIONS

The WMBI was most likely associated with earlier NEC onset, higher RBC transfusions, and less necrosis and greater hemorrhage lesions on intestinal pathology in preterm infants with surgical NEC.

IMPACT

In preterm infants with surgical NEC, brain MRI showed injury in the white matter in 52%, gray matter in 10%, and cerebellar region in 30%. Preterm infants with severe WMBI (grade 3-4) had less necrosis and greater hemorrhagic lesions on histopathology of the bowel. Preterm infants with WMBI were more likely to have a more severe postoperative course, AKI, and longer length of hospitalization. Neuroprotective strategies to prevent brain injury in preterm infants with surgical NEC are needed with the goal of improving the neurodevelopmental outcomes.

Clinical course of neonatal acute kidney injury: multi-center prospective cohort study

Background

Neonatal acute kidney injury (AKI) has been associated with unfavorable outcomes, including increased mortality. We aimed to describe the clinical course and outcomes during the first 7 days after diagnosis in newborns with AKI in three neonatal intensive care units in Popayán-Colombia.

Methods

Multi-center prospective cohort study conducted between June 2019 and December 2020 in three NICUs after ethical approval. We included newborns between 2 and 28 days of life, first diagnosed with AKI using the KDIGO classification modified for newborns which consider increased serum creatinine values over baseline values as well as urine output over time in hours or both. Patients with chromosomal abnormalities, major kidney malformations, and complex congenital heart disease were excluded. Patients were followed for up to 7 days after diagnosis and the maximum KDIGO stage, recovery of kidney function, need for renal replacement therapy and cumulative incidence of death were evaluated.

Results

Over the 18 months of the study, 4132 newborns were admitted to the NICUs, and 93 patients (2.25, 95% CI 1.82–2.75%) developed neonatal AKI. 59.1% of the newborns were premature and there were no differences in severity according to gestational age. During follow-up, the maximum KDIGO was 64.5% for AKI-stage 1, 11.8% for AKI-stage 2, and 23.7% for AKI-stage 3. Kidney function recovery was higher in AKI-stage 1 patients vs. AKI-severe (AKI-stage 2 and 3) (95% vs. 48.5%). Five patients (5.4%) received renal replacement therapy and 15 died (16.1%), four in AKI-stage 1 vs. 11 in AKI-severe (6.7% vs 33.3%).

Conclusions

Newborns admitted to the NICUs can develop AKI regardless of gestational age, and it is more frequent between the second and ninth days of life. More patients whit AKI-stage 1 recover and die less than those in a severe stage.

Systemic Hypertension in Infants with Bronchopulmonary Dysplasia

PURPOSE OF REVIEW

Neonatal hypertension is increasingly recognized as improvements in neonatal intensive care have led to increased survival of premature infants. Among infants with bronchopulmonary dysplasia (BPD), the rates of hypertension are much higher than the general neonatal population. However, the etiology and pathophysiology of this increased risk of hypertension in neonates with lung disease remain unclear.

RECENT FINDINGS

Among infants with bronchopulmonary dysplasia, the rates of hypertension are much higher than the general neonatal population. New studies suggest outcomes in neonates with BPD with hypertension are usually good, with resolution of hypertension in most infants with lung disease. Several potential mechanisms of hypertension in this patient population have been recently proposed. This review focuses on the recent epidemiologic data on prevalence of hypertension in neonates with bronchopulmonary dysplasia, reviews the typical clinical course, and discusses available strategies for management of infants with bronchopulmonary dysplasia that develop hypertension.

Accuracy of diagnosing acute kidney injury by assessing urine output within the first week of life in extremely preterm infants

BACKGROUND

Neonatal acute kidney injury (AKI) is associated with increased mortality and is often assessed with the neonatal modified Kidney Disease: improving Global Outcomes (KDIGO) classification, which uses changes in serum creatinine levels. However, because this classification has many drawbacks, a novel method, the neonatal Risk, Injury, Failure, Loss, and End-Stage Kidney Disease (nRIFLE) classification for diagnosing neonatal AKI according to urine output (UO), was recently proposed. To date, no data on the incidence of AKI according to nRIFLE are available for extremely preterm infants (born at gestational age less than 28 weeks). This study was conducted to clarify the association between incidence of AKI and in-hospital mortality in extremely preterm infants.

METHODS

Of 171 extremely preterm infants hospitalized from 2006 to 2020, 84 in whom indwelling bladder catheters were placed for UO measurements within 24 h of life were included. The incidence of AKI was assessed using the nRIFLE classification. In-hospital mortality was compared between patients with AKI and those without it.

RESULTS

The incidence of AKI during the first week of life was 56% and that of in-hospital mortality was significantly higher in patients with AKI (25.5%) than in those without it (2.8%). The odds ratio was 12.3 with 95% confidence interval ranging from 1.5 to 100.0.

CONCLUSION

The incidence of AKI according to nRIFLE was higher than reported in most previous studies using the neonatal modified KDIGO classification, suggesting that assessment by nRIFLE criteria using UO may improve diagnostic accuracy of AKI in extremely preterm infants.

Modifying the Renal Angina Index for Predicting AKI and Related Adverse Outcomes in Pediatric Heart Surgery

Background:Reliable prediction of severe acute kidney injury (AKI) and related poor outcomes has the potential to optimize treatment. The purpose of this study was to modify the renal angina index in pediatric cardiac surgery to predict severe AKI and related poor outcomes. Methods: We performed a multicenter retrospective study with the population divided into a derivation and validation cohort to assess the performance of a modified renal angina index assessed at 8 h after cardiac intensive care unit (CICU) admission to predict a complex outcome of severe day 3 AKI or related poor outcomes (ventilation duration >7 days, CICU length of stay >14 days, and mortality). The derivation sample was used to determine the optimal cut-off value. Results: There were 298 and 299 patients in the derivation and validation cohorts, respectively. The incidence of severe day 3 AKI and the complex outcome was 1.7% and 28% in the derivation and validation cohort. The sensitivity analysis for fulfillment of renal angina was a score >8 with a sensitivity of 63%, specificity of 73%, and negative predictive value of 83%. The cardiac renal angina index predicted the composite outcome with an area under the curve of 0.7 (95% confidence interval: 0.62-0.78). Renal angina patients had a significantly higher probability of the complex outcome when compared to individual risk and injury categories. Conclusions: We operationalized the renal angina index for use after cardiac surgery. Further revision and modification of the construct with integration of biomarkers in a prospective cohort are necessary to refine the prediction model.

Risk factors for acute kidney injury after pediatric cardiac surgery: a meta-analysis

BACKGROUND

Cardiac surgery-associated acute kidney injury (AKI) is associated with increased morbidity and mortality in both adults and children.

OBJECTIVES

This study aimed to identify clinical risk factors for AKI following cardiac surgery in the pediatric population.

DATA SOURCES

PubMed/MEDLINE, Embase, Scopus, and reference lists of relevant articles were searched for studies published by August 2020.

STUDY ELIGIBILITY CRITERIA

Studies were included if (1) the population consisted of pediatric patients (< 18 years old), (2) patients underwent cardiac surgery, (3) risk factors were compared between patients who developed AKI and those who did not, and (4) studies were prospective or retrospective observational studies or randomized controlled trials.

PARTICIPANTS AND INTERVENTIONS

Children undergoing pediatric cardiac surgery.

STUDY APPRAISAL AND SYNTHESIS METHODS

Random-effects meta-analysis was performed, comparing potential risk factors between pediatric patients who developed CS-AKI and those who did not.

RESULTS

Sixty-one publications including a total of 19,680 participants (AKI: 7257 participants; no AKI: 12,423 participants) were included from studies published between 2008 and 2020. The pooled estimated incidence of AKI was 34.3% (95% confidence interval 30.0-38.8%, I² = 96.8%). Binary risk factors that were significantly and consistently associated with AKI were the presence of pulmonary hypertension, cyanotic heart disease, univentricular heart, risk adjustment for congenital heart surgery 1 (RACHS-1) score ≥ 3, vasopressor use, cardiopulmonary bypass use, reoperation, and sepsis. Significant continuous risk factors included younger age, lower body weight, lower preoperative creatinine, higher preoperative estimated glomerular filtration rate (eGFR), higher RACHS-1 score, longer surgery time, longer cardiopulmonary bypass time, longer aortic cross-clamp time, and higher red blood cell transfusion volume.

LIMITATIONS

Results are limited by heterogeneity and potential residual confounding.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Our meta-analysis identified clinical risk factors that are associated with AKI in children undergoing cardiac surgery. This might help clinicians anticipate and manage more carefully this population and implement standardized preventive strategies.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42021262699. A higher resolution version of the Graphical abstract is available as Supplementary information.

Fluid Homeostasis and Diuretic Therapy in the Neonate

Understanding physiologic water balance and homeostasis mechanisms in the neonate is critical for clinicians in the NICU as pathologic fluid accumulation increases the risk for morbidity and mortality. In addition, once this process occurs, treatment is limited. In this review, we will cover fluid homeostasis in the neonate, explain the implications of prematurity on this process, discuss the complexity of fluid accumulation and the development of fluid overload, identify mitigation strategies, and review treatment options.

Neonatal Hypertension

Neonatal hypertension is uncommon but is becoming increasingly recognized. Normative blood pressure data are limited, as is research regarding the risks, treatment, and long-term outcomes. Therefore, there are no clinical practice guidelines and management is based on clinical judgment and expert opinion. Recognition of neonatal hypertension requires proper blood pressure measurement technique. When hypertension is present there should be a thorough clinical, laboratory, and imaging evaluation to promptly diagnose causes needing medical or surgical management. This review provides a practical overview for the practicing clinician regarding the identification, evaluation, and management of neonatal hypertension.

Prematurity and Low Birth Weight in Neonates as a Risk Factor for Obesity, Hypertension, and Chronic Kidney Disease in Pediatric and Adult Age

Low weight at birth may be due to intrauterine growth restriction or premature birth. Preterm birth is more common in low- and middle-income countries: 60% of preterm birth occur in sub-Saharan African or South Asian countries. However, in some higher-income countries, preterm birth rates appear to be increasing in relation to a reduction in the lower threshold of fetal viability. The cutoff is at 22–23 weeks, with a birth weight of approximately 500 g, although in developed countries such as Japan, the viability cutoff described is 21–22 weeks. There is evidence of the long-term consequences of prenatal programming of organ function and its relationship among adult diseases, such as hypertension (HT), central obesity, diabetes, metabolic syndrome, and chronic kidney disease (CKD). Premature delivery before the completion of nephrogenesis and intrauterine growth restriction leads to a reduction in the number of nephrons that are larger due to compensatory hyperfiltration and hypertrophy, which predisposes to the development of CKD in adulthood. In these patients, the long-term strategies are early evaluation and therapeutic interventions to decrease the described complications, by screening for HT, microalbuminuria and proteinuria, ultrasound monitoring, and renal function, with the emphasis on preventive measures. This review describes the effects of fetal programming on renal development and the risk of obesity, HT, and CKD in the future in patients with low birth weight (LBW), and the follow-up and therapeutic interventions to reduce these complications.

Improving the identification of acute kidney injury in the neonatal ICU: three centers' experiences

OBJECTIVE

To describe three different standardized approaches to improving neonatal acute kidney injury (AKI) identification and the impact on AKI identification, incidence, and nephrology consultation and referral.

STUDY DESIGN

A retrospective cohort study in three academic NICUs. We compared AKI identification, AKI incidence, nephrology consultation, and nephrology follow-up before and after implantation of local protocols to standardize neonatal AKI identification.

RESULT

Neonatal AKI identification improved in all three NICUs following protocol implementation (26-85%, P < 0.0001). Each center also saw increases in nephrology consultation (15-83%, P < 0.0001) and nephrology follow-up (7-73%, P < 0.0001). AKI incidence decreased significantly (21-12%, P < 0.0001).

CONCLUSION

Multiple strategies can be successfully operationalized to improve neonatal AKI identification. While different in approach, each strategy resulted in increased AKI identification and nephrology involvement. This study emphasizes the importance of local standardized approaches to AKI to improve AKI identification and nephrology involvement in the NICU.

Dosing of vancomycin and target attainment in neonates: a systematic review

INTRODUCTION

Neonatal infections caused by Gram-positive bacteria are commonly treated with vancomycin. However, there is a lack of agreement on the optimal vancomycin dosing regimen and corresponding vancomycin exposure to correlate with efficacy and toxicity.

OBJECTIVES

This review aimed to evaluate dosing of vancomycin in neonates, therapeutic target attainment and clinical toxicity and efficacy outcomes.

METHODS

Two electronic databases - Embase and PubMed (Medline) - were systematically searched between 1995-2020. Studies that reported dosing regimens, drug concentrations, toxicity, and efficacy of vancomycin in neonates were eligible for inclusion. Descriptive analysis and a narrative synthesis were performed.

RESULTS

The systematic review protocol was registered with the PROSPERO International Prospective Register of Systematic reviews in 2020 (registration number: CRD42020219568). Twenty-four studies were included for final analysis. Overall, the data from the included studies showed a great degree of heterogeneity. Therapeutic drug monitoring practices were different between institutions. Although most studies used trough concentration with a target range of 10-20 mg/L, target attainment was different across the studies. The probability of target attainment was < 80% in all tested dosing algorithms. Few studies reported on vancomycin efficacy and toxicity.

CONCLUSION

This is a comprehensive overview of dosing strategies of vancomycin in neonates. There was inadequate evidence to propose an optimal therapeutic regimen in the newborn population, based on the data obtained, due to the heterogeneity in the design and objectives of the included studies. Consistent and homogeneous comparative randomised clinical trials are needed to identify a dosing regimen with a probability of target attainment of > 90% without toxicity.

Acute kidney injury in premature and low birth weight neonates: a systematic review and meta-analysis

BACKGROUND

Acute kidney injury (AKI) is common and it is associated with poor clinical outcomes in premature and low birth weight neonates. This systematic review and meta-analysis was performed to summarize the literature and evaluate the prevalence, risk factors, and mortality of premature and low birth weight neonates with AKI.

METHODS

A systematic search in PubMed, Embase, and the Cochrane Library was performed. Studies on the prevalence, risk factors, diagnosis, and outcomes of acute kidney injury in preterm neonates and neonates with low birth weight were included and analyzed.

RESULTS

Fifty articles of 10,744 patients were included in this study. The overall rate of AKI from the pooled results of all patients was 25% (95% CI 20-30%) with heterogeneity among studies (I² = 97%; P < 0.01). Patients with AKI had significantly higher rate of mortality than patients without AKI (odds ratio (OR) = 7.13; 95% CI 5.91-8.60; P < 0.01).

CONCLUSIONS

AKI was prevalent and was associated with high mortality rate among preterm and low birth weight neonates.

Risk Factors and Consequences of Acute Kidney Injury After Noncardiac Surgery in Children

BACKGROUND

Postoperative acute kidney injury (AKI) is a serious complication that is associated with prolonged hospital stay, high risk of short-term postsurgical mortality, need for dialysis, and possible progression to chronic kidney disease. To date, very little data exist on the risk of postoperative AKI among children undergoing noncardiac surgical procedures. We used data from a large multicenter cohort to determine the factors associated with AKI among children who underwent inpatient noncardiac surgical procedures and its impact on the postoperative course.

METHODS

We utilized the National Surgical Quality Improvement Program Pediatric participant user files to identify a cohort of children who underwent inpatient surgery between 2012 and 2018 (n = 257,439). We randomly divided the study population into a derivation cohort of 193,082 (75%) and a validation cohort of 64,357 (25%), and constructed a multivariable logistic regression model to identify independent risk factors for AKI. We defined AKI as the occurrence of either acute renal failure or progressive renal insufficiency within the 30 days after surgery.

RESULTS

The overall rate of postoperative AKI was 0.10% (95% confidence interval [CI], 0.09-0.11). In a multivariable model, operating times longer than 140 minutes, preexisting hematologic disorder, and preoperative sepsis were the strongest independent predictors of AKI. Other independent risk factors for AKI were American Society of Anesthesiologists (ASA) physical status ≥III, preoperative inotropic support, gastrointestinal disease, ventilator dependency, and corticosteroid use. The 30-day mortality rate was 10.1% in children who developed AKI and 0.19% in their counterparts without AKI (P < .001). Children who developed AKI were more likely to require an extended hospital stay (≥75th percentile of the study cohort) relative to their peers without AKI (77.4% vs 21.0%; P < .001).

CONCLUSIONS

Independent preoperative risk factors for AKI in children undergoing inpatient noncardiac surgery were hematologic disorder, preoperative sepsis, ASA physical status ≥III, inotropic support, gastrointestinal disease, ventilator dependency, and steroid use. Children with AKI were 10 times more likely to die and nearly 3 times more likely to require an extended hospital stay, relative to their peers without AKI.

Are outcomes in congenital cardiac surgery better than ever?

BACKGROUND AND AIM OF THE STUDY

Congenital heart disease is the most common congenital defect among infants born in the United States. Within the first year of life, 1 in 4 of these infants will need surgery. Only one generation removed from an overall mortality of 14%, many changes have been introduced into the field. Have these changes measurably improved outcomes?

METHODS

The literature search was conducted through PubMed MEDLINE and Google Scholar from inception to October 31, 2021. Ultimately, 78 publications were chosen for inclusion.

RESULTS

The outcome of overall mortality has experienced continuous improvements in the modern era of the specialty despite the performance of more technically demanding surgeries on patients with complex comorbidities. This modality does not account for case-mix, however. In turn, clinical outcomes have not been consistent from center to center. Furthermore, variation in practice between institutions has also been documented. A recurring theme in the literature is a movement toward standardization and universalization. Examples include mortality risk-stratification that has allowed direct comparison of outcomes between programs and improved definitions of morbidities which provide an enhanced framework for diagnosis and management.

CONCLUSIONS

Overall mortality is now below 3%, which suggests that more patients are surviving their interventions than in any previous era in congenital cardiac surgery. Focus has transitioned from survival to improving the quality of life in the survivors by decreasing the incidence of morbidity and associated long-term effects. With the transformation toward standardization and interinstitutional collaboration, future advancements are expected.

Evaluation of Term Newborn Patients With Hypernatremic Dehydration

Aim

We aimed to evaluate the demographic, clinical, and laboratory findings and the management of newborns with hypernatremic dehydration (HDH).

Materials and Methods

A total of 85 term newborns with serum sodium (Na) levels higher than 145 mEq/L who admitted to our hospital between January 2011 and December 2018 were included in this study.

Results

Among all cases, 54.1% were female infants with the mean birth weight, weight loss ratio, and median age at diagnosis of 3095 ± 540 g, 13.6 ± 10%, and 8 (2-24) days, respectively. The most common presenting complaints were breastfeeding difficulties (90.5%), fever (63.5%), decreased urination (43.5%), jaundice (22.3%), and convulsion (15.3%). The mean sodium and potassium, and median blood urea and creatinine levels on admission were 167.9 ± 13.4 mEq/L, 5.4 ± 2.8 mmol/L, 213 mg/dL (11-476 mg/dL), and 2.4 mg/dL (0.52-9.96 mg/dL), respectively. There was metabolic acidosis in 67% and acute renal failure in 74.4% of patients, while peritoneal dialysis was performed in 12 of them. There was a positive correlation between weight loss ratio and admission age, serum urea, and creatinine levels; there was a negative correlation between weight loss and blood pH. Eight patients died (9.4%).

Conclusions

In our study, serum urea, creatinine, potassium, metabolic acidosis levels, convulsion, and dialysis requirements at the time of admission of the newborns with HDH were found to be higher in those who died compared to those who survived. Convulsion was a presenting complaint, and it was also observed during the treatment.

Extended Interval Aminoglycoside Treatment for Klebsiella Pneumoniae Endocarditis in an Extremely Low Birth Weight Neonate

Infective endocarditis (IE) in neonates is associated with high mortality and incidence has been increasing over the past two decades. The majority of very low birth weight infants will be treated with at least one nephrotoxic medication during their hospital course. Over one-quarter of very low birth weight neonates exposed to gentamicin may develop acute kidney injury (AKI); this is particularly worrisome as AKI is an independent factor associated with increased neonatal mortality and increased length of stay. AKI during periods of neonatal nephrogenesis, which continues until 34-36 weeks postmenstrual age, may also have serious effects on the long-term nephron development which subsequently puts infants at risk of chronic kidney disease. Extended interval (EI) aminoglycoside (AMG) dosing has been used for decades in adult populations and has proven to reduce AKI while being at least as effective as traditional dosing, although there is limited published research for using an EI AMG in endocarditis in adults or pediatric patients. We describe an extremely low birth weight neonate, born preterm at 24 weeks gestation treated for Klebsiella pneumoniae IE that required AMG therapy who also had concurrent AKI. We utilized EI AMG combination therapy for treatment of Klebsiella pneumoniae endocarditis with good outcome and encourage others to report their experiences to improve our knowledge of EI AMG in this population.

Optimizing fresh-frozen plasma transfusion in surgical neonates through thromboelastography: a quality improvement study

Fresh frozen plasma (FFP) is largely misused in the neonatal setting. The aim of the study is to evaluate the impact of a Thromboelastography (TEG)-based Quality Improvement (QI) project on perioperative FFP use and neonatal outcomes. Retrospective pre-post implementation study in a level-III NICU including all neonates undergoing major non-cardiac surgery before (01-12/2017) and after (01-12/2019) the intervention. In 2018, the intervention included the following: (1) Training on TEG, (2) Implementation of TEG, and (3) Algorithm for TEG-directed FFP administration in surgical neonates. We compared pre- vs post-intervention patient characteristics, hemostasis, and clinical management. Linear and logistic regression models were used to evaluate the impact of the project on main outcomes. We analyzed 139 neonates (pre-intervention: 72/post-intervention: 67) with a mean (± SD) gestational age (GA) 34.9 (± 5) weeks and birthweight 2265 (± 980) grams which were exposed to 184 surgical procedures (pre-intervention: 91/post-intervention: 93). Baseline characteristics were similar between periods. In 2019, prothrombin time (PT) was longer (14.3 vs 13.2 s; p < 0.05) and fibrinogen was lower (229 vs 265 mg/dl; p < 0.05), if compared to 2017. In 2019, the intraoperative exposure to FFP decreased (31% vs 60%, p < 0.001), while the pre-operative FFP use did not change. The reduction of intraoperative FFP did not impact on mortality and morbidity. Intraoperative FFP use was lower in the post-intervention even after controlling for GA, American Society of Anesthesiologists score, PT, and fibrinogen (Odds ratio: 0.167; 95% CI: 0.070, 0.371).   Conclusion: The TEG-based QI project for the management of FFP during neonatal surgery reduced intraoperative FFP exposure. What is Known: • PT and aPTT are poor predictors of bleeding risk in acquired neonatal coagulopathy, leading to likely unnecessary fresh frozen plasma (FFP) transfusion in the Neonatal Intensive Care Setting.  • As neonatal hemostasis is a delicate balance between the concomitant reduction of pro- and anti-coagulants drivers, thromboelastography (TEG) is a promising alternative for coagulation monitoring. What is New: • The implementation of TEG, training, and shared protocols contributed to reduced intraoperative FFP use, which was not associated with increased mortality or bleeding events. • These findings inform future research showing that there is clinical equipoise to allow for larger studies to confirm the use of TEG in NICUs and to identify TEG cut-offs for transfusion practice.

Furosemide clearance in very preterm neonates early in life: A pilot study using scavenged samples

BACKGROUND

Furosemide is an off-label drug, frequently used as a diuretic in neonates with oliguria and/or edema. Its clearance in preterm neonates is lower than in term neonates or children. We aimed, herein, to clarify furosemide clearance (CL) in very preterm (VP) neonates (<28 weeks' gestation) within the first 2 weeks of life and identify the factors predictive of the pharmacokinetics (PK) parameters, such as CL.

METHODS

Furosemide was administered at 0.5 or 1 mg/kg in a 0.5-h infusion via a syringe pump; blood samples were drawn from an artery or vein after the intravenous injection. The serum furosemide concentration was measured using high-performance liquid chromatography. The PK parameters were then analyzed using Bayesian estimation.

RESULTS

Thirteen blood samples were obtained from 10 VP neonates after intravenous injection. The mean postconceptional age and mean postnatal days at exposure to furosemide were 26.9 weeks and 7.1 days, respectively. The estimated mean CL was 16.5 mL/kg/h. The mean distribution volume (Vd) and elimination half-life (t1/2) were 0.37 L/kg and 15.3 h, respectively. Furosemide CL was negatively associated with serum creatinine (SCr) [CL = 84.2 - 67.1 × SCr (mg/dL)].

CONCLUSIONS

Very preterm neonates within the first 2 weeks of life had a higher CL than subjects in other preterm neonatal studies. The SCr level was the sole parameter influencing furosemide CL and might serve as a good index for furosemide dosing in VP neonates.

Perspectives: Neonatal acute kidney injury (AKI) in low and middle income countries (LMIC)

Neonatal AKI (NAKI) remains a challenge in low- and middle-income countries (LMICs). In this perspective, we address issues of diagnosis and risk factors particular to less well-resourced regions. The conservative management pre-kidney replacement therapy (pre-KRT) is prioritized and challenges of KRT are described with improvised dialysis techniques also included. Special emphasis is placed on ethical and palliation principles.

The comparison of three different acute kidney injury classification systems after congenital heart surgery

BACKGROUND

We aimed to compare the frequency of acute kidney injury (AKI) and its effects on mortality and morbidity with different classification systems in pediatric patients who had surgery under cardiopulmonary bypass for congenital heart disease.

METHODS

This study included children younger than 18 years old who were followed up in the pediatric cardiac intensive care unit between September 1 and December 1, 2020, after congenital heart surgery with cardiopulmonary bypass. Each case was categorized postoperatively in terms of AKI using Pediatric-Modified Risk, Injury, Failure, Loss, and End-Stage (pRIFLE), Acute Kidney Injury Network (AKIN), and Kidney Disease: Improving Global Outcomes (KDIGO). Hospital mortality (developed within the first 30 days postoperatively) and morbidity (longer than 7 days intensive care unit stay) were compared by three model classes. Results were evaluated statistically.

RESULTS

One hundred patients were included in the study. The median age was 3 months (1 day-180 months). Acute kidney injury was diagnosed in 49% of the cases according to the pRIFLE classification. It was diagnosed in 31% of the patients by AKIN classification. It was diagnosed in 41% of the patients with the KDIGO criteria. Morbidity was observed in 25% (n = 25) of all cases. The morbidity predictor was 0.800 for pRIFLE, 0.747 for AKIN and 0.853 for KDIGO by receiver operating characteristics analysis. All three categories predicted morbidity significantly (P < 0.001). Mortality was 10% (n = 10) for all groups. The mortality predictor was 0.783 for pRIFLE, 0.717 for AKIN and 0.794 for KDIGO by receiver operating characteristics analysis, and all three categories predicted mortality significantly (P < 0.001).

CONCLUSIONS

Regardless of the three methods used, AKI was commonly detected in pediatric patients undergoing congenital heart surgery. pRIFLE classification diagnosed more patients with AKI than AKIN and KDIGO. The KDIGO and pRIFLE classifications were better in predicting hospital mortality.

Study of neonatal acute kidney injury based on KDIGO criteria

BACKGROUND

Significant advancement has occurred over the years in diagnosis, recognition, intervention and impact of acute kidney injury (AKI) on morbidity and mortality in critically-ill neonates. However an increased risk of chronic kidney disease (CKD) is still observed among neonates who survive an episode of AKI. Therefore, preventing and adequately managing AKI in neonates could help in controlling long-term renal morbidity in neonates who develop AKI. Thus, this study was undertaken with the aim of studying the incidence, contributing factors and outcomes of AKI in at-risk term neonates admitted to the neonatal intensive care unit (NICU).

METHODS

One hundred and ninety-six term neonates admitted to the NICU with sepsis, hypoxic ischemic encephalopathy (HIE), dehydration and respiratory distress were enrolled and evaluated over a period of one year. Detailed maternal history along with neonatal history, anthropometry, vitals and clinical signs of neonates were recorded in a pretested proforma. Urine output was measured in all at-risk neonates. Serum creatinine was estimated to categorize AKI into stages as per modified KDIGO criteria.

RESULTS

Incidence of AKI was 21%, (n = 107 out of 510 admissions) in the study. Mortality was significantly higher in AKI stage III neonates (88.9%) (p < 0.001). Multivariate analysis revealed that hypoxic ischemic encephalopathy (HIE) had 35.293 (p < 0.001) times higher risk, while sepsis had 35.701 (p < 0.001), dehydration had 30.260 times (p < 0.001) and respiratory distress had 10.366 times (p < 0.001) higher risk of developing AKI.

CONCLUSION

Our study recorded a high incidence of AKI among at-risk neonates. KDIGO criteria for diagnosing AKI is feasible to apply in the at-risk neonates and helps in its early identification. Early diagnosis and timely intervention in neonates with HIE, sepsis, dehydration and respiratory can prevent the progression of AKI and thus improve prognoses.

Neonatal AKI profile using KDIGO guidelines: A cohort study in tertiary care hospital ICU of Lahore, Pakistan

BACKGROUND AND OBJECTIVE

Acute kidney injury (AKI) was observed in sick neonates and was associated with poor outcomes. Our cohort represents the neonatal characteristics of those diagnosed with AKI using Kidney Disease: Improved Global Outcome (KDIGO) guidelines.

METHODOLOGY

A cohort study was conducted in the NICU of FMH from June 2019 to May 2021. Data were collected on a proforma. All continuous variables were not normally distributed and expressed as the median and interquartile range. Categorical variables were analyzed by proportional differences with the Pearson chi-square test or Fisher's exact tests. A multinomial logistic regression model was used to explore the independent risk factors for AKI. Time to the event (death) and the cohort's survival curves were plotted using the Cox proportional hazard model.

RESULTS

AKI occurred in 473 (37.6%) neonates. The risk factors of AKI were outborn birth [adjusted odds ratio (AOR): 3.987, 95% confidence interval (CI): 2.564-6.200, p: 0.000], birth asphyxia (AOR: 3.567, 95% CI: 2.093-6.080, p: 0.000), inotropic agent (AOR: 2.060, 95% CI: 1.436-2.957, p: 0.000), antenatal steroids (AOR: 1.721, 95% CI: 1.213-2.443, p: 0.002), central lines (AOR: 1.630, 95% CI: 1.155-2.298, p: 0.005) and intraventricular hemorrhage (IVH)/intracranial hemorrhage/disseminated intravascular coagulopathy (AOR: 1.580, 95% CI: 1.119-2.231, p: 0.009). AKI significantly increases the duration of stay and mortality rates by 16.5% vs. 3.9% in neonates with normal renal function (p < 0.001).

CONCLUSION

About one-third of critically sick neonates had AKI. Significant risk factors for AKI were outborn birth, asphyxia inotropic agents, necrotizing enterocolitis, antenatal steroids central lines, and IVH. AKI is associated with an increased length of stay and increased mortality.

Extracorporeal Membrane Oxygenation After Norwood Surgery in Patients With Hypoplastic Left Heart Syndrome: A Retrospective Single-Center Cohort Study From Brazil

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is increasingly being used to support patients after the repair of congenital heart disease.

OBJECTIVE

We report our experience with patients with a single functional ventricle who were supported by ECMO after the Norwood procedure, reviewing the outcomes and identifying risk factors for mortality in these patients.

METHODS

In this single-center retrospective cohort study, we enrolled 33 patients with hypoplastic left heart syndrome (HLHS) who received ECMO support after the Norwood procedure between January 2015 and December 2019. The independent variables evaluated in this study were demographic, anatomical, and those directly related to ECMO support (ECMO indication, local of initiation, time under support, and urinary output while on ECMO). The dependent variable was survival. A p < 0.05 was considered statistically significant.

RESULTS

The ECMO support was applied in 33 patients in a group of 120 patients submitted to Norwood procedure (28%). Aortic atresia was present in 72.7% of patients and mitral atresia in 51.5%. For 15% of patients, ECMO was initiated in the operating room; for all other patients, ECMO was initiated in the intensive care unit. The indications for ECMO in the cardiac intensive care unit were cardiac arrest in 22 (79%) of patients, low cardiac output state in 10 (18%), and arrhythmia in 1 patient (3%). The median time under support was 5 (2-25) days. The median follow-up time was 59 (4-150) days. Global survival to Norwood procedure was 90.9% during the 30-day follow-up, being 33.3% for those submitted to ECMO. Longer ECMO support (p = 0.004) was associated with a higher risk of death in the group submitted to ECMO.

CONCLUSIONS

The mortality of patients with HLHS who received ECMO support after stage 1 palliation was high. Patients with low urine output were related to worse survival rates, and longer periods under ECMO support (more than 9 days of ECMO) were associated with 100% mortality. Earlier ECMO initiation before multiorgan damage may improve results.

Management of Acute Kidney Injury in Extremely Low Birth Weight Infants

Acute kidney injury (AKI) is a common problem in the neonatal intensive care unit (NICU). Neonates born at <1,000 g (extremely low birth weight, ELBW) are at an increased risk of secondary associated comorbidities such as intrauterine growth restriction, prematurity, volume restriction, ischaemic injury, among others. Studies estimate up to 50% ELBW infants experience at least one episode of AKI during their NICU stay. Although no curative treatment for AKI currently exists, recognition is vital to reduce potential ongoing injury and mitigate long-term consequences of AKI. However, the definition of AKI is imperfect in this population and presents clinical challenges to correct identification, thus contributing to under recognition and reporting. Additionally, the absence of guidelines for the management of AKI in ELBW infants has led to variations in practice. This review summarizes AKI in the ELBW infant and includes suggestions such as close observation of daily fluid balance, review of medications to reduce nephrotoxic exposure, management of electrolytes, maximizing nutrition, and the use of diuretics and/or dialysis when appropriate.

Association of high-sensitivity C-reactive protein and anemia with acute kidney injury in neonates

BACKGROUND

The association of high-sensitivity C-reactive protein (hsCRP) and anemia with postoperative acute kidney injury (AKI) in neonates with congenital heart disease (CHD) is still unclear. The purpose of this study was to examine whether anemia-associated AKI is modulated by hsCRP in neonates.

METHODS

This study included 253 consecutive neonatal patients who underwent CHD surgery in a national tertiary hospital. We investigated the association between postoperative AKI with baseline hsCRP, anemia, and their interaction by multivariable logistic regression analyses.

RESULTS

The incidence of AKI was 24.1% in the entire cohort. After being adjusted for covariates, hsCRP level was negatively correlated with AKI (P < 0.01 for 1 mg/L threshold), whereas anemia emerged as an independent risk factor of AKI (P = 0.02). In addition, there was a significant interaction between anemia and hsCRP level (P = 0.01). In neonates with hsCRP < 1 mg/L, anemia was positively associated with AKI (P = 0.03). However, no significant association was found between anemia and AKI in the context of hsCRP ≥ 1 mg/L. Combination of anemia and hsCRP < 1 mg/L was independently correlated with the risk of AKI (P < 0.01), while concomitant anemia and hsCRP ≥ 1 mg/L or hsCRP < 1 mg/L combined with non-anemia was not.

CONCLUSIONS

In neonates with CHD, the risk of anemia-associated AKI may be modulated by hsCRP level. Attention should be paid to neonates with preoperative anemia and baseline hsCRP < 1 mg/L to reduce the risk of postoperative AKI.

Peritoneal dialysis in very low and extremely low birthweight infants: A pooled analysis

BACKGROUND

Peritoneal dialysis (PD) represents an important therapeutic option in neonatal acute kidney injury (AKI), although evidence regarding its effects in preterm neonates remains unclear. The present study aims to evaluate the feasibility of PD in very low birthweight (VLBW) and extremely low birthweight (ELBW) infants and clarify the association of catheter choice with clinical outcomes.

METHODS

Medline, Scopus, Web of Science, Clinicaltrials.gov and CENTRAL databases were systematically searched from inception to 15 January 2021. Studies reporting individual participant data of VLBW and ELBW infants treated with PD were selected.

RESULTS

Overall, 20 studies were included comprising 101 patients. Catheter-related complications were significantly more frequent among ELBW infants (odds ratio: 5.18, 95% confidence intervals (CI): 1.23-29.09). After inverse probability treatment weighting, compared to drainage catheters, death risk was significantly lower with the use of PD (hazard ratio: 0.42, 95% CI: 0.19-0.90) but not vascular catheters (hazard ratio: 0.58, 95% CI: 0.28-1.20). Similarly, kidney function loss was significantly lower only with the implementation of PD catheters (hazard ratio: 0.44, 95% CI: 0.21-0.94).

CONCLUSIONS

PD is a feasible kidney replacement therapy modality in VLBW and ELBW infants with AKI. The use of drainage catheters may be linked to significantly worse kidney recovery and overall survival rates, compared to PD catheters. Future cohorts should confirm the most appropriate catheter type and contribute to the standardisation of PD procedures.

Diuretic therapy and acute kidney injury in preterm neonates and infants

BACKGROUND

Acute kidney injury (AKI) in preterm infants is associated with prolonged hospitalization and high mortality. Diuretic therapy has been used to enhance urine output in preterm infants with AKI. Treatment with diuretics, prescription patterns, and relationship with length of stay (LOS), mechanical ventilation (MV), and mortality in preterm infants who also had AKI have not been fully evaluated.

METHODS

This multicenter retrospective study used the Pediatric Hospital Information System database. We included 2121 preterm infants with AKI diagnosis from 46 hospital Neonatal Intensive Care Units (NICUs) born <37 weeks gestational age (GA). Treatment with diuretics, practice patterns across 46 NICUs in the USA, and associated outcomes including LOS, MV, and mortality were evaluated.

RESULTS

Seventy-six percent of infants received at least one dose of diuretics (median treatment 18 days). Diuretic prescription varied significantly across hospitals and ranged from 42 to 96%. Diuretics were used more frequently in infants with younger GA and smaller birth weight. Infants with older GA who received diuretics at or before 28 days postnatally had worse survival even after adjusting for known confounders.

CONCLUSIONS

Preterm infants with AKI diagnosis were frequently treated with diuretics. Moreover, infants with younger GA and smaller birth weight were more likely to receive diuretics. Worse survival in infants with older GA who received diuretics could be the result of more underlying severe illness in these infants and not the cause of more severe illness. Prospective studies are needed to best determine patient safety and outcomes with diuretic treatment in preterm infants with AKI. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

Advances in Neonatal Acute Kidney Injury

In this state-of-the-art review, we highlight the major advances over the last 5 years in neonatal acute kidney injury (AKI). Large multicenter studies reveal that neonatal AKI is common and independently associated with increased morbidity and mortality. The natural course of neonatal AKI, along with the risk factors, mitigation strategies, and the role of AKI on short- and long-term outcomes, is becoming clearer. Specific progress has been made in identifying potential preventive strategies for AKI, such as the use of caffeine in premature neonates, theophylline in neonates with hypoxic-ischemic encephalopathy, and nephrotoxic medication monitoring programs. New evidence highlights the importance of the kidney in "crosstalk" between other organs and how AKI likely plays a critical role in other organ development and injury, such as intraventricular hemorrhage and lung disease. New technology has resulted in advancement in prevention and improvements in the current management in neonates with severe AKI. With specific continuous renal replacement therapy machines designed for neonates, this therapy is now available and is being used with increasing frequency in NICUs. Moving forward, biomarkers, such as urinary neutrophil gelatinase-associated lipocalin, and other new technologies, such as monitoring of renal tissue oxygenation and nephron counting, will likely play an increased role in identification of AKI and those most vulnerable for chronic kidney disease. Future research needs to be focused on determining the optimal follow-up strategy for neonates with a history of AKI to detect chronic kidney disease.

Neonatal acute kidney injury: a case-based approach

Neonatal acute kidney injury (AKI) is increasingly recognized as a common complication in critically ill neonates. Over the last 5-10 years, there have been significant advancements which have improved our understanding and ability to care for neonates with kidney disease. A variety of factors contribute to an increased risk of AKI in neonates, including decreased nephron mass and immature tubular function. Multiple factors complicate the diagnosis of AKI including low glomerular filtration rate at birth and challenges with serum creatinine as a marker of kidney function in newborns. AKI in neonates is often multifactorial, but the cause can be identified with careful diagnostic evaluation. The best approach to treatment in such patients may include diuretic therapies or kidney support therapy. Data for long-term outcomes are limited but suggest an increased risk of chronic kidney disease (CKD) and hypertension in these infants. We use a case-based approach throughout this review to illustrate these concepts and highlight important evidence gaps in the diagnosis and management of neonatal AKI.

Epidemiology of neonatal acute kidney injury after cardiac surgery without cardiopulmonary bypass

BACKGROUND

The purpose of this Neonatal and Pediatric Heart and Renal Outcomes Network (NEPHRON) study was to describe the epidemiology and outcomes of CS-AKI after cardiac surgery without cardiopulmonary bypass (non-CPB).

METHODS

We performed a retrospective study of neonates (≤30 days) who underwent non-CPB cardiac surgery at 22 centers affiliated with the Pediatric Cardiac Critical Care Consortium. CS-AKI was defined using the modified Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine (SCr) and urine output criteria from postoperative day (POD) 0-6. CS-AKI by SCr was further subclassified into transient (resolved by POD3) and persistent/late (≥3 days). Multivariable regression analyses were used to determine risk factors for CS-AKI, and associations with outcomes of ventilation hours and cardiac intensive care unit length of stay (LOS).

RESULTS

582 neonates [median age at surgery: 9 days (IQR:5-15 days), 25% functional single ventricle] were included. CS-AKI occurred in 38.3%: rate and severity varied across centers. Aggregate daily CS-AKI prevalence peaked on POD1 (17.1%). No stage of CS-AKI was associated with ventilation hours or LOS. Persistent/late CS-AKI occurred in 48 (8%). Prostaglandin use and single ventricle surgery were associated with persistent/late CS-AKI. Higher baseline SCr, but not persistent/late CS-AKI was associated with longer ventilation duration and ICU LOS after adjusting for confounders.

CONCLUSIONS

KDIGO-defined CS-AKI occurred commonly in neonates undergoing non-CPB cardiac surgery. However, most CS-AKI was transient, and no CS-AKI classification was associated with worse outcomes. Further work is needed to determine the CS-AKI definition that best associates with outcomes in this cohort.

Neonatal Life-Threatening Nonoliguric Hyperkalemia Under Therapeutic Hypothermia

To illustrate our experience with two cases of neonatal life-threatening hyperkalemia during therapeutic hypothermia (TH) despite a normal acid-base status, urine output, and preserved renal function. Clinical cases are presented from Pediatric Intensive Care Unit (PICU) admission to the onset of the hyperkalemia, with related complications and after resolution. Similar cases were not retrieved from a critical review of pertinent literature. Severe hyperkalemia pathophysiology and risk factors have been debated. Two full-term adequate for weight female neonates were admitted to PICU because of perinatal asphyxia who underwent TH. Prenatal history was completely uneventful, nor hereditary genetic conditions were reported; moreover, long-term follow-up ruled out any metabolic or renal disease. Despite an accurate evaluation of previous clinical series and literature on TH and perinatal asphyxia, these hyperkalemic episodes remain unexplained. The hypoxic-ischemic insult may affect multiple organs, mainly central nervous system, heart, lung, and kidneys; acute muscle breakdown and consequent rising of myoglobin may also have a precipitating role in acute kidney failure (AKF) and hyperkalemia. Electrolyte imbalance is a possible finding as a consequence of combined cell injury and AKF. In contrast, an isolated severe hyperkalemia is exceedingly rare in nonoliguric neonates.

Evaluating the Incidence of Sepsis Post-Central Catheter Removal When Using Prophylactic Vancomycin in the Neonatal Intensive Care Unit

OBJECTIVE

With no consensus, the practice of using prophylactic antibiotics prior to central venous catheter (CVC) removal in NICU patients remains controversial. The objective of this study was to compare the incidence of sepsis post-CVC removal in those who received a dose of vancomycin prophylactically with those who did not.

METHODS

This single-center, retrospective chart review included NICU patients who had CVCs removed. Patients were excluded if they had a confirmed or suspected infection at the time of CVC removal or if the indwelling CVC was removed prior to 30 days from insertion. Primary outcome was the occurrence of a sepsis evaluation within 72 hours from CVC removal. Secondary outcomes included the development of acute kidney injury, source and identification of positive cultures, time to onset of suspected or confirmed sepsis, and the appropriate administration of intravenous vancomycin.

RESULTS

Eighty-two CVC removals received prophylactic vancomycin (P-VAN), and 22 CVCs did not receive prophylactic vancomycin (NP-VAN) prior to CVC removal. There were no significant differences in patient demographics between groups and median duration of indwelling CVC. Two clinical sepsis evaluations occurred in the P-VAN group compared with none in the NP-VAN group. Of all the P-VAN CVC removals, 45 (55%) received vancomycin appropriately. There were no statistical differences in all evaluated secondary outcomes.

CONCLUSIONS

Vancomycin administered prophylactically prior to CVC removal did not reduce the number of subsequent clinical sepsis evaluations or infections in NICU patients.

Severe acute kidney injury in neonates with necrotizing enterocolitis: risk factors and outcomes

BACKGROUND

To study the risk factors and outcomes of severe acute kidney injury (AKI) in neonates with necrotizing enterocolitis.

METHODS

Retrospective chart review of 202 neonates with necrotizing enterocolitis (NEC) (Bell stage >IIa) from 2013 to 2018. AKI was defined as per-modified neonatal Kidney Disease: Improving Global Outcomes criteria. Demographic, clinical, and outcome data were compared between neonates without severe AKI (stage 0 and 1 AKI) and those with severe AKI (stage 2 and 3 AKI).

RESULTS

Severe AKI occurred in 66/202 (32.6%) of neonates after NEC diagnosis and after 61/104 (58.7%) of surgical NEC diagnoses. On adjusted model, surgical NEC [adjusted odds ratio (aOR) = 30.6; 95% confidence interval (CI) = 8.9, 130.6], outborn [aOR = 3.9; 95% CI = 1.54, 11.0], exposure to antenatal steroids [aOR = 3.0; 95% CI = 1.1, 8.9], and positive blood culture sepsis [aOR = 3.5; 95% CI = 1.3, 10.0] had increased odds for severe AKI. Those with severe AKI required longer hospitalization [124 days (interquartile range (IQR) 88-187) vs. 82 days (IQR 42-126), p < 0.001].

CONCLUSIONS

Severe AKI is common in neonates with NEC who require surgical intervention, are outborn, have positive blood culture sepsis, and receive antenatal steroids. Severe AKI is associated with a significantly longer length of hospitalization.

IMPACT

Neonates with NEC, who are transferred from outside hospitals, require surgical NEC management, and/or have a positive blood culture at NEC onset are at the highest odds for severe (stages 2 and 3) AKI. Assessment of urine output is important for patients with NEC. Without it, 11% of those with severe AKI would have been misdiagnosed using serum creatinine alone. Kidney-protective strategies in the pre-, peri-, and postoperative period may improve the morbidity and mortality associated with severe AKI in neonates with NEC.

Biomarkers of renal function in preterm neonates at 72h and 3weeks of life

OBJECTIVE

Serum levels of creatinine in neonates are quite variable and suffer interference from the immature kidney and maternal creatinine concentration. The aim of this study was to measure novel biomarkers of glomerular and tubular function in healthy preterm neonates at 72h and 3 weeks of life.

METHODS

Urine samples were collected in 40 preterm neonates with 28-34 incomplete weeks of gestational age. None of the participants had comorbidities, malformations and infections. The samples were collected at 72h of life and at 3 weeks after birth. Measurements of Calbindin, Collagen IV, FABP1, αGST, IP-10, KIM-1, Osteoactivin, Renin, TFF-3, TIMP-1, α-1-Microglobulin, Albumin, Clusterin, Cystatin C, EGF, Lipocalin-2/NGAL and Osteopontin were performed using panels 1 and 2 of multiplex kits of kidney injury. Data were analyzed using the software GraphPad Prism version 6.0.

RESULTS

The preterm neonates included 55% of males with gestational age of 30±1 weeks. The most frequent maternal condition associated with preterm birth was preeclampsia (80%). Molecules related to glomerular function showed a significant increase in the concentrations obtained at 3 weeks of life compared to 72h of life. Markers related to tubular injury (KIM-1 and NGAL) also showed an increase. On the other hand, cystatin C did not change.

CONCLUSION

The elevation of molecules related to glomerular function indicates an increase of glomerular filtration rate from 72h up until 3 weeks of life, which was not clearly detected with the measurement of cystatin C.

Trends and racial disparities for acute kidney injury in premature infants: the US national database

BACKGROUND

To assess prevalence and outcomes of acute kidney injury (AKI) in very-low-birth-weight infants.

METHODS

This cross-sectional study utilized the National Inpatient Sample (NIS) dataset for years 2000-2017. All premature infants with birth weight (BW) <1500g and/or gestational age (GA) ≤32 weeks were included. Analyses were conducted for overall population and two BW categories: <1000g and 1000-1499g. Adjusted odds ratios were calculated after controlling for confounding variables in logistic regression analysis. Cochrane-Armitage test was used to assess for statistically significant trends in AKI frequency over the years.

RESULTS

In total, 1,311,681 hospitalized premature infants were included; 19,603 (1.5%) were diagnosed with AKI. The majority (74.3%) were BW <1000g and 63.9% ≤28 weeks gestation. Prevalence of AKI differed by ethnicity; White had significantly less AKI than Black (OR=0.79, p<0.001) and Hispanic (OR=0.83, p<0.001). AKI was significantly associated with higher mortality compared to controls (35.1 vs. 3.0%, p<0.001). AKI was associated with comorbidities such as necrotizing enterocolitis, patent ductus arteriosus, bronchopulmonary dysplasia, intraventricular hemorrhage, and septicemia. In a regression model, AKI was associated with higher mortality after controlling confounding factors (aOR=7.79, p<0.001). AKI was associated with significant increase in length of stay (p<0.001) and cost of hospitalization in survivors (p<0.001). There is a significant trend for increased AKI frequency over the years (Z score=4.33, p<0.001).

CONCLUSION

AKI is associated with increased mortality and comorbidities in preterm infants, especially in infants with BW <1000g. Further studies are needed to understand precipitating factors and assess preventative measures for this serious complication.

Renal tissue desaturation and acute kidney injury in infant cardiac surgery: a prospective propensity score-matched cohort study

BACKGROUND

Previous studies on the association between renal tissue desaturation and acute kidney injury (AKI) in infant cardiac surgery are limited by small sample sizes and inconsistent results. This prospective study aimed to determine the association between renal desaturation and AKI in infants undergoing surgical repair of an isolated ventricular septal defect (VSD).

METHODS

Infants undergoing VSD repair involving cardiopulmonary bypass participated in this prospective cohort study. The exposure of interest was renal tissue desaturation, defined as at least 20% decrease in saturation from baseline for at least 60 consecutive seconds. Intraoperative care was not guided by renal oxygenation, as the anaesthesiologists were blinded to the monitor. The outcome was AKI arising within postoperative Days 1-3. The primary analysis was based on propensity score-matched infants with and without intraoperative renal desaturation.

RESULTS

Intraoperative renal desaturation was detected in 38 of 242 infants using near-infrared spectroscopy. This group of infants was matched with 114 infants without intraoperative renal saturation after propensity score matching. Acute kidney injury occurred in 47% (18/38) and 27% (31/114) of infants with or without renal desaturation, respectively. Infants with renal desaturation had higher odds of developing AKI than infants without renal desaturation based on conditional logistic regression (odds ratio 2.79; 95% confidence interval: 1.21-6.44; P=0.016). The cumulative time of renal desaturation correlated moderately with the ratio of postoperative peak creatinine to preoperative baseline creatinine (r=0.51; P<0.001).

CONCLUSIONS

Intraoperative renal desaturation is associated with increased odds of developing AKI after surgical repair of an isolated VSD involving cardiopulmonary bypass in infants.

CLINICAL TRIAL REGISTRATION

NCT03941015.

Renal Oxygenation (rSO2) Population Parameter Estimates in Premature Infants Routinely Monitored With Near-Infrared Spectroscopy

BACKGROUND

Currently, reference ranges for renal oxygenation measured by near-infrared spectroscopy (NIRS) in preterm infants beyond the first days of life are lacking, especially those born prior to 29 weeks' gestation. Population estimates of renal oxygenation (rSO2) levels among preterm infants over time have yet to be established, leading to reluctance in clinical application.

PURPOSE

To characterize the distribution and estimate population parameters for renal oxygenation measured by NIRS during the first 14 days of life among preterm infants.

METHODS

We prospectively observed rSO2 trends of 37 infants before 34 weeks' gestation and 1800-g or less birth weight for the first 14 days of life. Analyses included distribution fit tests, ordinary least squares (OLS) regression, and t tests.

RESULTS

Average daily rSO2 variation steadily increased with 42% difference through the first 14 days of life. For all infants, renal rSO2 means peaked during the first 3 days of life and plateaued around 7 days. Daily rSO2 slopes were significantly lower among males and infants 29 weeks' or less gestation.

IMPLICATIONS FOR PRACTICE

Renal rSO2 during the first 14 days of life reflects normal extrauterine transition reaching stabilization around 7 days of life. Gestational age, birth weight, and gender may predict the early trajectory of rSO2 patterns. Population estimates provide parameters for renal rSO2 that may indicate early-onset tissue hypoxia when acute or significant drops from baseline occur.

IMPLICATIONS FOR RESEARCH

We present a framework to guide future research using renal NIRS technology in preterm infants to determine deviations from expected trends that may precede renal injury.

Neonatal Acute Kidney Injury: Understanding of the Impact on the Smallest Patients

The study of neonatal acute kidney injury (AKI) has transitioned from small, single-center studies to the development of a large, multicenter cohort. The scope of research has expanded from assessment of incidence and mortality to analysis of more specific risk factors, novel urinary biomarkers, interplay between AKI and other organ systems, impact of fluid overload, and quality improvement efforts. The intensification has occurred through collaboration between the neonatology and nephrology communities. This review discusses 2 case scenarios to illustrate the clinical presentation of neonatal AKI, important risk factors, and approaches to minimize AKI events and adverse long-term outcomes.

Nephrotoxicity in Neonates

Acute kidney injury (AKI) is classified based on prerenal, intrinsic, and postrenal causes. In the newborn, AKI can occur after an insult during the prenatal, perinatal, or postnatal period. AKI is usually an underrecognized condition and its true incidence is unknown. AKI may result from the administration of a number of different nephrotoxic medications, which are often used concurrently in critically ill neonates, exponentially increasing the risk of renal injury. Drug toxicity may also compromise the formation and development of nephrons, and this is particularly important in preterm infants, who have incomplete nephrogenesis. Little is known about the pharmacokinetics and pharmacodynamics of different medications used in neonates, especially for the most immature infant, and the use of most medications in this population is off label. Strategies to prevent AKI include the avoidance of hypotension, hypovolemia, fluid imbalances, hypoxia, and sepsis as well as judicious use of nephrotoxic medications. Treatment strategies aim to maintain fluids and electrolytic and acid-base homeostasis, along with an adequate nutritional status. Neonates are especially prone to long-term sequelae of AKI and benefit from long-term follow-up. This review summarizes the most relevant aspects of nephrotoxicity in neonates and describes the prevention, treatment, and follow-up of AKI in neonates.

Renal Oxygenation Measured by Near-Infrared Spectroscopy in Neonates

BACKGROUND

Acute kidney injury (AKI) affects approximately 30% of infants admitted to the neonatal intensive care unit (NICU), and increases mortality risk by 50%. Current diagnostic criteria (serum creatinine rise with oliguria) cannot detect early-onset AKI, as up to 50% of nephron damage may occur by the time these abnormalities present. Once AKI is established, clinical management is often ineffective; therefore, prevention is key. Near-infrared spectroscopy (NIRS) offers a feasible, noninvasive approach to continuously monitor renal oxygenation trends over time, serving as a surrogate marker for renal perfusion.

PURPOSE

To provide an overview of NIRS principles for measuring renal oxygenation, and to describe current evidence of how this technology is being used among infants admitted to the NICU relative to the prediction and identification of AKI.

METHODS

A comprehensive search of PubMed and CINHAL focused on renal NIRS studies in NICU preterm and term infants was conducted.

RESULTS

Findings from 34 studies were included. In term infants, reduced renal oxygenation correlated to invasive SvO2 monitoring, predicted survivability and AKI. In preterm infants, reduced renal oxygenation was associated with AKI in one study, yet contrasting findings were reported in those with patent ductus arteriosus, including those who received prostaglandin inhibitors. Normative data in all infants were sparse.

IMPLICATIONS FOR PRACTICE

Renal NIRS may offer a noninvasive measurement of kidney hypoperfusion that may precede conventional diagnostic measures.

IMPLICATIONS FOR RESEARCH

Normative data are lacking, the threshold for renal ischemia is not defined, and consensus guiding clinical treatment based on NIRS data is nonexistent.

Temporal Trends of Acute Kidney Injury and Associated Risk Exposures in Extremely Preterm Infants

BACKGROUND AND OBJECTIVES

Neonatal AKI in the preterm population is an under-recognized morbidity. Detecting AKI in preterm infants is important for their long-term kidney health. We aimed to examine the yearly trends of incidence and the related morbidities and care practices affecting the occurrence of neonatal AKI in extremely preterm (gestational age <29 weeks) and very preterm (gestational age 29-32 weeks) infants.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The trends and the related risk factors and care practices of AKI were examined in the extremely preterm (n=434) and very preterm (n=257) infants who were admitted within 14 days after birth from 2005 to 2018 to the University Hospital and had at least two serum creatinine measurements during hospitalization. We defined AKI as a serum creatinine rise of 0.3 mg/dl or more within 48 hours or a 1.5-fold increase within 7 days.

RESULTS

The extremely preterm group had a three-fold higher incidence of AKI (30% versus 10%) than the very preterm group. Among preterm infants with AKI, 92% had one episode of AKI, and 45% experienced stage 2 or 3 AKI; the mean duration of AKI was 12±9 days. Across the 14-year period, the crude incidence of AKI declined markedly from 56% to 17% in the extremely preterm group and from 23% to 6% in the very preterm group. After adjustment, a significant decline of AKI incidence was still observed in the extremely preterm group. The declining AKI in the extremely preterm infants was related to the trends of decreasing incidences of neonatal transfer, prolonged aminoglycoside exposure, prophylactic use of nonsteroidal anti-inflammatory drugs, and sepsis.

CONCLUSIONS

We observed a declining trend in the incidence of neonatal AKI among extremely preterm infants from 2005 to 2018, which may be related to improvement of care practices.

Acute kidney injury

Acute kidney injury (AKI) is defined by a sudden loss of excretory kidney function. AKI is part of a range of conditions summarized as acute kidney diseases and disorders (AKD), in which slow deterioration of kidney function or persistent kidney dysfunction is associated with an irreversible loss of kidney cells and nephrons, which can lead to chronic kidney disease (CKD). New biomarkers to identify injury before function loss await clinical implementation. AKI and AKD are a global concern. In low-income and middle-income countries, infections and hypovolaemic shock are the predominant causes of AKI. In high-income countries, AKI mostly occurs in elderly patients who are in hospital, and is related to sepsis, drugs or invasive procedures. Infection and trauma-related AKI and AKD are frequent in all regions. The large spectrum of AKI implies diverse pathophysiological mechanisms. AKI management in critical care settings is challenging, including appropriate volume control, nephrotoxic drug management, and the timing and type of kidney support. Fluid and electrolyte management are essential. As AKI can be lethal, kidney replacement therapy is frequently required. AKI has a poor prognosis in critically ill patients. Long-term consequences of AKI and AKD include CKD and cardiovascular morbidity. Thus, prevention and early detection of AKI are essential.

Acute Kidney Injury in Neonates with Perinatal Asphyxia Receiving Therapeutic Hypothermia

OBJECTIVE

To assess the incidence and severity of acute kidney injury (AKI) and evaluate risk factors that predict AKI in asphyxiated infants receiving therapeutic hypothermia.

STUDY DESIGN

Infants ≥36 weeks' gestation diagnosed with moderate-to-severe perinatal asphyxia and received therapeutic hypothermia were reviewed retrospectively (n = 166). Modified Acute Kidney Injury Network criteria were used to diagnose AKI. The results of infants with AKI were compared with the infants who did not develop AKI.

RESULTS

AKI developed in 49 (29.5%) infants, of whom 22 had stage I, 13 had stage II, and 14 had stage III AKI. The overall mortality rate was 15.7% and was significantly higher in infants with AKI when compared with infants without AKI (41 vs. 5%; p < 0.001). Asystole at birth (p = 0.044), placental abruption (p = 0.041), outborn status (p = 0.041), need for vasopressor support (p = 0.031), increased bleeding tendency (p = 0.031), initial lactate level (p = 0.015), and 12-hour lactate level (p = 0.029) were independent risk factors for the development of AKI. Receiver operating characteristic curve analysis demonstrated a good predictive value for initial lactate level (>15 mmol/L), with 69% sensitivity (95% CI: 55-82) and 82% specificity (95% CI: 74-89), and for 12-hour lactate level (>6 mmol/L), with 83.7% sensitivity (95% CI: 70-93) and 73.5% specificity (95% CI: 64.5-81), to predict AKI.

CONCLUSION

AKI is still a common complication of perinatal asphyxia despite treatment with therapeutic hypothermia. Identification of risk factors associated with the development of AKI in asphyxiated infants would be potentially beneficial to reduce morbidity and mortality. Besides perinatal risk factors, initial and 12-hour lactate concentrations can be used for the early prediction of AKI.