Smaller circuits for smaller patients: improving renal support therapy with Aquadex™

The Brophy Kit: A Manual Hemodialysis Device for Neonates

Introduction

Acute kidney injury (AKI) is common in critically ill neonates, including very and extremely low birth weight (VLBW, ELBW) neonates. In severe cases, kidney replacement therapy (KRT) may be warranted. Currently, available KRT devices are only indicated for those weighing ≥ 2.5 kg and require a double lumen or 2 separate single lumen catheters. We miniaturized the Kirpa Kit manual dialysis device, naming it the Brophy Kit, and we assessed its in vitro clearance and ultrafiltration (UF) performance.

Methods

We diluted packed red blood cells to a normal hematocrit (Hct: 31.1%-36.8%) and conducted 12 clearance and 3 UF experiments. A cycle consisted of aspirating 10 ml of blood from the blood bag, passing it through a hemofilter, and returning it in a circular path. For clearance experiments, we tested 4 configurations, with varied timing and volume of saline flushes to refresh the dialysis compartment, then measured blood urea nitrogen (BUN) and potassium concentrations every 5 cycles. For each UF cycle, 1 ml of ultrafiltrate was removed, and Hct was measured every 10 cycles.

Results

Median BUN and potassium reduction were 31.0% (interquartile range [IQR]: 17.6-37.9) and 35.0% (IQR: 26.9-41.7), respectively, after 30 clearance cycles. Median Hct increased to 52.6% (IQR: 52.5-53.8) after 60 UF cycles, more than the expected Hct (47.7%).

Conclusion

The Brophy Kit performs in vitro clearance efficiently and UF consistently. The Brophy Kit may address a technological KRT gap for small neonates because of its minimal extracorporeal volume and ability to function with single lumen access.

Vascular Access for Renal Replacement Therapy in Neonates and Infants: A Single Center Experience

INTRODUCTION

Neonatal renal replacement therapy (RRT) is a treatment modality used for severe kidney failure. Historically, its use has been limited in small infants due to circuits with large extra-corporeal volumes that require large double lumen vascular catheters. We sought to review our institution's experience with vascular access and overall survival in infants who receive RRT.

METHODS

A retrospective chart review of infants less than 5 kg (kg) was performed at our free-standing children's hospital from January 2016 to July 2023. We assessed the number of catheters used per patient, location of catheter placements, size of catheter, duration of treatment, reasons for line removal, and mortality.

RESULTS

A total of 93 neonatal patients were identified who underwent RRT. Thirty-two patients (34.4%) required more than one catheter, with a total of 145 catheters placed for this cohort. The median (IQR) weight at insertion was 3.3 kg (2.7-4.0). The most common location for placement was the right internal jugular vein (n = 114, 78.6%). Patients required catheters for RRT for a median (IQR) of 16 days (7-39). Six patients underwent catheter placement at a weight of less than 2 kg. Nineteen total patients went on to peritoneal dialysis (20.4%). Fifty-three patients died during their admission (57.0%).

CONCLUSION

To our knowledge this is the largest review of catheter use for RRT in infants within an intensive care unit and it reveals the success in treating renal failure in even the smallest infants.

LEVEL OF EVIDENCE

IV, Treatment Study.

Severe Fetal CAKUT (Congenital Anomalies of the Kidneys and Urinary Tract), Prenatal Consultations, and Initiation of Neonatal Dialysis

INTRODUCTION

Pediatric nephrology prenatal consultations for congenital anomalies of the kidney and urinary tract (CAKUT) and criteria for kidney replacement therapy initiation in neonatal end-stage kidney disease (ESKD) are not well described. We evaluated pediatric nephrology approaches to prenatal CAKUT counseling and neonatal dialysis initiation.

METHODS

A 35-question Qualtrics survey was distributed via the North American Pediatric Renal Trials and Collaborative Studies email list between January and March 2021. Thirty-nine pediatric nephrology centers completed the survey.

RESULTS

All but one responding center (n = 38) provide prenatal CAKUT consultations and neonatal dialysis, with wide variability in reported multispecialty involvement. Nearly half (47%) of centers utilize written/unwritten criteria for offering neonatal dialysis. The most common contraindications to neonatal dialysis were parental refusal (61%), contraindication to access placement by surgeons (55%), and birth weight (BW) contraindication (55%, with < 1,500 g being the most common BW contraindication). Overall, 79% of centers reported caring for < 5 neonates with ESKD in the past year, 61% use hemodialysis therapies prior to peritoneal dialysis in neonates requiring dialysis, and 100% transition to peritoneal dialysis by hospital discharge.

CONCLUSION

Many pediatric nephrology programs provide prenatal CAKUT consultations and neonatal dialysis, but with variability in practice approach. Further multicenter research regarding prenatal consultations and neonatal dialysis outcomes is necessary to further improve care delivery to this population.

Recent Advances in Kidney Replacement Therapy in Infants: A Review

Kidney replacement therapy (KRT) is used to treat children and adults with acute kidney injury (AKI), fluid overload, kidney failure, inborn errors of metabolism, and severe electrolyte abnormalities. Peritoneal dialysis and extracorporeal hemodialysis/filtration can be performed for different durations (intermittent, prolonged intermittent, and continuous) through either adaptation of adult devices or use of infant-specific devices. Each of these modalities have advantages and disadvantages, and often multiple modalities are used depending on the scenario and patient-specific needs. Traditionally, these therapies have been challenging to deliver in infants due the lack of infant-specific devices, small patient size, required extracorporeal volumes, and the risk of hemodynamic stability during the initiation of KRT. In this review, we discuss challenges, recent advancements, and optimal approaches to provide KRT in hospitalized infants, including a discussion of peritoneal dialysis and extracorporeal therapies. We discuss each specific KRT modality, review newer infant-specific devices, and highlight the benefits and limitations of each modality. We also discuss the ethical implications for the care of infants who need KRT and areas for future research.

Survival of Infants With Severe Congenital Kidney Disease After ECMO and Kidney Support Therapy

Congenital kidney failure not only affects the homeostatic functions of the kidney, but also affects neonatal respiratory integrity. Until recently, extracorporeal membrane oxygenation (ECMO) support was not used in this population because the need for ECMO clearly established nonviability. Since 2016, 31 neonates have been admitted to the NICU at Children's of Alabama with congenital kidney failure. Five patients were placed on ECMO for severe respiratory distress unresponsive to conventional interventions. We evaluated neonates with congenital kidney failure and pulmonary hypoplasia/hypertension refractory to conventional therapies who received ECMO support within the first 9 postnatal days. We describe the pre and postnatal diagnoses, ECMO course details, dialysis modalities, complications, procedures, and long-term outcomes of these patients. All 5 patients received kidney support therapy by postnatal day 7. Diagnoses included posterior urethral valves, bilateral renal dysplasia, and autosomal recessive polycystic kidney disease. Gestational age ranged from 35.6 to 37.1 weeks. Birth weight ranged from 2740 to 3140 g. Days on ECMO ranged from 4 to 23. Four survived and are living today. Pulmonary hypertension resolved in surviving patients. Three surviving patients require no oxygen support, and 1 patient requires nocturnal oxygen. Three survivors received a kidney transplant, and 1 awaits transplant evaluation. Patients with congenital kidney failure with severe pulmonary hypoplasia/pulmonary hypertension no longer warrant a reflexive assignment of nonviability. Meticulous ECMO, respiratory, nutritional, and kidney support therapies may achieve a favorable long-term outcome. Further investigation of strategies for optimal outcome is needed.

Programs and processes for advancing pediatric acute kidney support therapy in hospitalized and critically ill children: a report from the 26th Acute Disease Quality Initiative (ADQI) consensus conference

Pediatric acute kidney support therapy (paKST) programs aim to reliably provide safe, effective, and timely extracorporeal supportive care for acutely and critically ill pediatric patients with acute kidney injury (AKI), fluid and electrolyte derangements, and/or toxin accumulation with a goal of improving both hospital-based and lifelong outcomes. Little is known about optimal ways to configure paKST teams and programs, pediatric-specific aspects of delivering high-quality paKST, strategies for transitioning from acute continuous modes of paKST to facilitate rehabilitation, or providing effective short- and long-term follow-up. As part of the 26th Acute Disease Quality Initiative Conference, the first to focus on a pediatric population, we summarize here the current state of knowledge in paKST programs and technology, identify key knowledge gaps in the field, and propose a framework for current best practices and future research in paKST.

Validation of a low-cost continuous renal replacement therapy dialysate fluid controller for experimental purposes

BACKGROUND

Continuous renal replacement therapy (CRRT) support is crucial for critically ill patients and it is underexplored in specific situations. Experimental CRRT offers a means to gain insights into these scenarios, but the prohibitive cost of CRRT machines limits their accessibility. This study aimed to develop and validate a low-cost and precise dialysate controller for experimental CRRT.

RESULTS

Our results demonstrate a commendable level of precision in affluent flow control, with a robust correlation (R2 = 0.99) for continuous flow and a strong correlation (R2 = 0.95) for intermittent flow. Additionally, we observed acceptable agreement with a bias = 3.4 mL (upper limit 95% = 43.9 mL and lower limit 95% = - 37 mL) for continuous flow and bias = - 20.9 mL (upper limit 95% = 54 mL and lower limit 95% = - 95.7 mL) for intermittent flow, in this way, offering a precise CRRT dose for the subjects. Furthermore, we achieved excellent precision in the cumulative ultrafiltration net (UFnet), with a bias = - 2.8 mL (upper limit 95% = 6.5 mL and lower limit 95% = - 12 mL). These results remained consistent even at low affluent flow rates of 8, 12, and 20 mL/min, which are compatible with CRRT doses of 25-30 mL/kg for medium-sized animals. Moreover, the acceptable precision of our findings persisted when the dialysate controller was subjected to high filter dialysate chamber pressure for an extended duration, up to 797 min.

CONCLUSIONS

The low-cost dialysate controller developed and tested in this study offers a precise means of regulating CRRT in experimental settings. Its affordability and accuracy render it a valuable instrument for studying CRRT support in unconventional clinical scenarios, particularly in middle-income countries' experimental ICU laboratories.

Using aquapheresis with continuous hematocrit monitoring to guide ultrafiltration

BACKGROUND

Management of edema and volume overload in patients with hypoalbuminemia, either due to nephrotic syndrome or other disease processes, can be extremely challenging.

METHODS

We describe the management of five patients with hypoalbuminemia and severe fluid overload using the Aquadex FlexFlow device with continuous hematocrit monitoring to guide ultrafiltration.

RESULTS

We report five pediatric patients ranging in age from 7 days to 11 years and in size from 2.7 to 65 kg with hypoalbuminemia due to a variety of etiologies treated with slow continuous ultrafiltration with continuous hematocrit monitoring to guide ultrafiltration using the Aquadex device. Treatment allowed successful fluid removal in all cases, without hypotension or other hemodynamic complications.

CONCLUSIONS

In a variety of clinical circumstances and in patients from infants to adolescence, we report that patients with diuretic-resistant fluid overload can be treated with Aquadex using continuous hematocrit monitoring to guide management to allow fluid removal without hemodynamic instability or other complications. A higher resolution version of the Graphical abstract is available as Supplementary information.

New perspectives in pediatric dialysis technologies: the case for neonates and infants with acute kidney injury

Advancements in pediatric dialysis generally rely on adaptation of technology originally developed for adults. However, in the last decade, particular attention has been paid to neonatal extracorporeal therapies for acute kidney care, an area in which technology has made giant strides in recent years. Peritoneal dialysis (PD) is the kidney replacement therapy (KRT) of choice in the youngest age group because of its simplicity and effectiveness. However, extracorporeal blood purification provides more rapid clearance of solutes and faster fluid removal. Hemodialysis (HD) and continuous KRT (CKRT) are thus the most used dialysis modalities for pediatric acute kidney injury (AKI) in developed countries. The utilization of extracorporeal dialysis for small children is associated with a series of clinical and technical challenges which have discouraged the use of CKRT in this population. The revolution in the management of AKI in newborns has started recently with the development of new CKRT machines for small infants. These new devices have a small extracorporeal volume that potentially prevents the use of blood to prime lines and dialyzer, allow a better volume control and the use of small-sized catheter without compromising the blood flow amount. Thanks to the development of new dedicated devices, we are currently dealing with a true "scientific revolution" in the management of neonates and infants who require an acute kidney support.

A simplified protocol of regional citrate anticoagulation with phosphate-containing solutions in infants and children treated with continuous kidney replacement therapy

BACKGROUND

Regional citrate anticoagulation (RCA) is the preferred modality of anticoagulation used in continuous kidney replacement therapy (CKRT) in adults and less extensively in children. Potential metabolic complications limit widespread use in infants, neonates, and in children with liver failure.

METHODS

We report our experience with a simplified protocol in 50 critically ill children, infants, and neonates, some of them with liver failure, with commercially available solutions containing phosphorous and higher concentration of potassium and magnesium.

RESULTS

RCA allowed attainment of a mean filter lifetime of 54.5 ± 18.2 h, 42.5% of circuits lasted more than 70 h, and scheduled change was the most frequent cause of CKRT interruption. Patient Ca++ and circuit Ca++ were maintained in the target range with mean values of 1.15 ± 0.13 mmol/l and 0.38 ± 0.07 mmol/l, respectively. No session had to be stopped because of metabolic complications. The most frequent complications were hyponatremia, hypomagnesemia, and metabolic acidosis mostly related to primary disease and critical illness. No session had to be stopped because of citrate accumulation (CA). Transitory CA occurred in 6 patients and was managed without requiring RCA interruption. No patients with liver failure presented CA episodes.

CONCLUSIONS

In our experience, RCA with commercially available solutions was easily applied and managed in critically ill children, even in patients with low weight or with liver failure. Solutions containing phosphate and higher concentrations of magnesium and potassium allowed reduction of metabolic derangement during CKRT. Prolonged filter life was ensured with no detrimental effects on patients and reduced staff workload. A higher resolution version of the Graphical abstract is available as Supplementary information.

CARPEDIEM® for continuous kidney replacement therapy in neonates and small infants: a French multicenter retrospective study

BACKGROUND

The Cardio-Renal Pediatric Dialysis Emergency Machine (CA.R.P.E.D.I.E.M.®) device is a continuous kidney replacement therapy (CKRT) equipment dedicated to neonates and small infants. This study aimed to assess the effectiveness, feasibility, outcomes, and technical considerations relating to CARPEDIEM® use.

METHODS

This retrospective multicenter study included 19 newborns and six infants receiving CARPEDIEM® in five French pediatric and neonatal intensive care units. Laboratory parameters were collected at the initiation and end of the first CARPEDIEM® session. Results are presented as median [IQR] (range).

RESULTS

At initiation, age was 4 days [2-13] (1-1134) with a body weight of 3.3 kg [2.5-4] (1.3-11.1). Overall, 131 sessions and 2125 h of treatment were performed. Treatment duration per patient was 42 h [24-91] (8-557). Continuous veno-venous hemofiltration (CVVH) was performed in 20 children. Blood flow rate was 8 mL/kg/min [6-9] (3-16). The effluent flow rate for CVVH was 74 mL/kg/h [43-99] (28-125) and net ultrafiltration (UF) 6 mL/kg/h [2-8] (1-12). In the five children treated by hemodialysis, the blood and dialysate flow rates were 6 mL/kg/min [5-7] (4-7) and 600 mL/h [300-600] (120-600), respectively, while session duration was 8 h [6-12] (2-24). Most infants required a catheter between 4.5 and 6.5 French. Hemodynamic instability with a need for volume replacement occurred in 31 sessions (23%). Thrombocytopenia was observed in 29 sessions (22%). No hemorrhage occurred; all the patients survived the sessions, but only eight patients (32%) were alive at hospital discharge.

CONCLUSIONS

These data confirm that the use of CARPEDIEM® is safe and effective in critically ill neonates and infants. A higher resolution version of the Graphical abstract is available as Supplementary information.

Safety and efficacy of continuous renal replacement therapy for children less than 10 kg using standard adult machines

Continuous Renal Replacement Therapy (CRRT) machines are used off-label in patients less than 20 kg. Infant and neonates-dedicated CRRT machines are making their way into current practice, but these machines are available only in select centres. This study assesses the safety and efficacy of CRRT using adult CRRT machines in children ≤ 10 kg and to determines the factors affecting the circuit life in these children.

DESIGN

Retrospective cohort study of children ≤ 10 kg who received CRRT (January 2010-January 2018) at a PICU in a tertiary care centre in London, UK. Primary diagnosis, markers for illness severity, CRRT characteristics, length of PICU admission and survival to PICU discharge were collected. Descriptive analysis compared survivors and non-survivors. A subgroup analysis compared children ≤ 5 kg to children 5-10 kg. Fifty-one patients ≤ 10 kg received 10,328 h of CRRT, with median weight of 5 kg. 52.94% survived to hospital discharge. Median circuit life was 44 h (IQR 24-68). Bleeding episodes occurred with 6.7% of sessions and hypotension for 11.9%. Analysis of efficacy showed a reduction in fluid overload at 48 h (P = 0.0002) and serum creatinine at 24 and 48 h (P = 0.001). Blood priming was deemed to be safe as serum potassium decreased at 4 h (P = 0.005); there was no significant change in serum calcium. Survivors had a lower PIM2 score at PICU admission (P < 0.001) and had longer PICU length of stay (P < 0.001).    Conclusion: Pending neonatal and infant dedicated CRRT machines, CRRT can be safely and effectively applied to children weighing ≤ 10 kg using adult-sized CRRT machines.

WHAT IS KNOWN

• Continuous Renal Replacement Therapy can be used for a variety of renal and non-renal indications to improve outcomes for children in the paediatric intensive care unit. These include, persistent oliguria, fluid overload, hyperkalaemia, metabolic acidosis, hyperlactatemia, hyperammonaemia, and hepatic encephalopathy. • Young children ≤ 10 kg are most often treated using standard adult machines, off-label. This potentially places them at risk of side effects due to high extracorporeal circuit volumes, relatively higher blood flows, and difficulty in achieving vascular access.

WHAT IS NEW

• This study found that standard adult machines were effective in reducing fluid overload and creatinine in children ≤ 10 kg. This study also assessed safety of blood priming in this group and found no evidence of an acute fall in haemoglobin or calcium, and a fall in serum potassium by a median of 0.3 mmol/L. The frequency of bleeding episodes was 6.7%, and hypotension requiring vasopressors or fluid resuscitation occurred with 11.9% of treatment sessions. • These findings suggest that adult CRRT machines are sufficiently safe and efficacious for routine use in PICU for children ≤ 10 kg and suggest that further research is undertaken, regarding the routine rollout of dedicated machines.

Method to Alleviate Dilutional Coagulopathy Caused by Continuous Renal Replacement Therapy Introduction in a Low-Birth-Weight Neonate: A Case Report

Continuous renal replacement therapy (CRRT) in neonates and children has recently been used to treat hyperammonemia and metabolic disorders. However, CRRT introduction in low-birth-weight neonates is still a challenge due to vascular access limitations, bleeding complications, and a lack of neonatal-specific devices. We present the case of a low-birth-weight neonate whose severe coagulopathy due to CRRT introduction with a red cell concentration-primed circuit was alleviated by priming the new circuit with blood from the current circuit. This male preterm infant (birth weight: 1,935 g) was admitted to the pediatric intensive care unit at two days old with metabolic acidosis and hyperammonemia, which required CRRT. Following CRRT introduction, he showed marked thrombocytopenia (platelet count: 305,000-59,000/μL) and coagulopathy (prothrombin time international normalized ratio (PT/INR) >10), necessitating platelet and fresh frozen plasma transfusions. Upon circuit exchange, we primed the new circuit with blood from the current circuit. This resulted in only a slight worsening of thrombocytopenia (platelet count: 56,000-32,000/μL) and almost no change in coagulation (PT/INR: 1.42-1.54). We also reviewed the literature regarding safe CRRT management in low-birth-weight neonates. Since there is no established method for the use of blood from the current circuit during circuit exchange, this should be addressed in future work.

Kidney replacement therapy in neonates: utilization trends and outcomes

BACKGROUND

We aimed to assess prevalence and clinical characteristics of newborns receiving kidney replacement therapy (KRT).

METHODS

We used the National Inpatient Sample (NIS) dataset for the years 2000-2017. Newborns treated with peritoneal dialysis (PD), hemodialysis (HD), and continuous KRT (CKRT) were included. Trend analysis using the Cochran-Armitage test was used to assess prevalence over the years.

RESULTS

A total of 64,532,552 hospitalized newborns were included. Among the 4281 infants treated with KRT, 2501 (58.4%) were treated with PD, 997 (23.3%) had HD, and 783 (18.3%) used CKRT. Associated diagnoses included congenital kidney anomalies (37.4% vs. 15% vs. 9.5%), urinary tract anomalies (35% vs. 12.5% vs. 6.3%), and congenital heart disease (68% vs. 25.7% vs. 72.3%). Median length of stay was longest in PD patients (39 days vs. 18 days vs. 26 days), respectively. However, cost of hospitalization was greatest in CKRT patients (US $490,916 vs. US $218,514 vs. US $621,554), respectively. In the entire cohort, 54,424 newborns had acute kidney injury (AKI); of them 16,999 (31%) died. KRT was used in 2,688 (4.9%) of infants with AKI. Over the study period, trends for utilization of PD (from 0.042 to 0.06%) and CKRT (from 0.03 to 0.21%) increased whereas the hemodialysis trend decreased (from 0.021 to 0.013%).

CONCLUSIONS

Congenital heart disease (CHD) and congenital anomalies of the kidneys and urinary tract (CAKUT) are the major diagnoses in newborns receiving KRT. Utilization of PD was greater than HD and CKRT. Trends of PD and CKRT utilization increased over time. Less than 5% of infants diagnosed with AKI received KRT.

Neonatal fluid overload-ignorance is no longer bliss

Excessive accumulation of fluid may result in interstitial edema and multiorgan dysfunction. Over the past few decades, the detrimental impact of fluid overload has been further defined in adult and pediatric populations. Growing evidence highlights the importance of monitoring, preventing, managing, and treating fluid overload appropriately. Translating this knowledge to neonates is difficult as they have different disease pathophysiologies, and because neonatal physiology changes rapidly postnatally in many of the organ systems (i.e., skin, kidneys, and cardiovascular, pulmonary, and gastrointestinal). Thus, evaluations of the optimal targets for fluid balance need to consider the disease state as well as the gestational and postmenstrual age of the infant. Integration of what is known about neonatal fluid overload with individual alterations in physiology is imperative in clinical management. This comprehensive review will address what is known about the epidemiology and pathophysiology of neonatal fluid overload and highlight the known knowledge gaps. Finally, we provide clinical recommendations for monitoring, prevention, and treatment of fluid overload.

Acute kidney injury and early fluid load in a retrospective cohort of neonatal sepsis

BACKGROUND

Sepsis and acute kidney injury (AKI) are associated with mortality in the newborn intensive care unit (NICU). There is a paucity of studies that describe AKI and fluid overload in neonatal sepsis and their association with mortality.

METHODS

Retrospective study of neonates with culture positive sepsis admitted to the NICU between June 2020 and June 2021 was conducted. Primary outcome was in-hospital mortality according to AKI as defined by the neonatal modified Kidney Diseases Improving Outcomes criteria. Secondary outcomes were early fluid overload and vasopressor use.

RESULTS

Thirty-three percent of neonates had AKI with sepsis, and 57% of cases were severe AKI. AKI was associated with mortality after adjusting for variables that were different between survivors and non-survivors (aOR 5.7 [95% CI 1.1-36], p = 0.04). Early fluid overload occurred in 27% of neonates who were at higher risk of having AKI with sepsis (OR 7.4 [95% CI 1.6-26.0], p = 0.01) and higher risk of mortality (aOR 17.8 [95% CI 2-7545], p = 0.02).

CONCLUSIONS

AKI and early fluid overload are associated with mortality in sepsis in our retrospective cohort. Mitigating AKI and early fluid overload in sepsis might be a fruitful strategy in reducing mortality with sepsis. A higher resolution version of the Graphical abstract is available as Supplementary information.

Kidney support for babies: building a comprehensive and integrated neonatal kidney support therapy program

Kidney support therapy (KST), previously referred to as Renal Replacement Therapy, is utilized to treat children and adults with severe acute kidney injury (AKI), fluid overload, inborn errors of metabolism, and kidney failure. Several forms of KST are available including peritoneal dialysis (PD), intermittent hemodialysis (iHD), and continuous kidney support therapy (CKST). Traditionally, extracorporeal KST (CKST and iHD) in neonates has had unique challenges related to small patient size, lack of neonatal-specific devices, and risk of hemodynamic instability due to large extracorporeal circuit volume relative to patient total blood volume. Thus, PD has been the most commonly used modality in infants, followed by CKST and iHD. In recent years, CKST machines designed for small children and novel filters with smaller extracorporeal circuit volumes have emerged and are being used in many centers to provide neonatal KST for toxin removal and to achieve fluid and electrolyte homeostasis, increasing the options available for this unique and vulnerable group. These new treatment options create a dramatic paradigm shift with recalibration of the benefit: risk equation. Renewed focus on the infrastructure required to deliver neonatal KST safely and effectively is essential, especially in programs/units that do not traditionally provide KST to neonates. Building and implementing a neonatal KST program requires an expert multidisciplinary team with strong institutional support. In this review, we first describe the available neonatal KST modalities including newer neonatal and infant-specific platforms. Then, we describe the steps needed to develop and sustain a neonatal KST team, including recommendations for provider and nursing staff training. Finally, we describe how quality improvement initiatives can be integrated into programs.

Delivering optimal renal replacement therapy to critically ill patients with acute kidney injury

Critical illness is often complicated by acute kidney injury (AKI). In patients with severe AKI, renal replacement therapy (RRT) is deployed to address metabolic dysfunction and volume excess until kidney function recovers. This review is intended to provide a comprehensive update on key aspects of RRT prescription and delivery to critically ill patients. Recently completed trials have enhanced the evidence base regarding several RRT practices, most notably the timing of RRT initiation and anticoagulation for continuous therapies. Better evidence is still needed to clarify several aspects of care including optimal targets for ultrafiltration and effective strategies for RRT weaning and discontinuation.

Kidney Replacement Therapy in Low Birth Weight Preterm Newborns

Managing newborns with kidney failure is a complex undertaking; even under ideal circumstances, dialysis is technically challenging and available therapies are designed for adults. These issues are exacerbated in smaller newborns, and intervention has traditionally not been offered in those below a certain weight threshold. Ethical concerns abound and patients deemed too small for dialysis are typically transitioned to comfort or palliative care. However, many of these neonates are otherwise healthy and would be considered survivable if kidney replacement therapy were available. To challenge the existing paradigm, we present 7 preterm, low birth weight neonates with end-stage kidney disease who were successfully managed using an innovative approach to kidney replacement therapy. These newborns had a median gestational age of 32 weeks (interquartile range [IQR], 32-35) and a median birth weight of 1.58 kg (IQR, 1.41-2.01). Kidney replacement therapy was initiated at a median age of 16 days (IQR, 1.5-40) and a weight of 1.85 kg (IQR, 1.57-2.1). Five of the 7 newborns (71%) survived to hospital discharge. Kidney replacement therapy was provided using 3F and 4F single lumen catheters and a modified ultrafiltration device. Patients experienced excellent metabolic control, and fluid homeostasis was achieved in the first week of life. Furthermore, survivors experienced physiologic weight gain and linear growth throughout their hospitalization. These findings, although preliminary, are encouraging for our smallest patients with kidney failure and suggest that survivability thresholds should be reexamined. At a minimum, neonatologists should be aware that novel approaches exist and may be considered for these challenging patients.

Genetic Etiologies, Diagnosis, and Management of Neonatal Cystic Kidney Disease

Fetal kidney development is a complex and carefully orchestrated process. The proper formation of kidney tissue involves many transcription factors and signaling pathways. Pathogenic variants in the genes that encodethese factors and proteins can result in neonatal cystic kidney disease. Advancements in genomic sequencing have allowed us to identify many of these variants and better understand the genetic underpinnings for an increasing number of presentations of childhood kidney disorders. This review discusses the genes essential in kidney development, particularly those involved in the structure and function of primary cilia, and implications of gene identification for prognostication and management of cystic kidney disorders.

Blood Filters in Children with COVID-19 and AKI: A Review

COVID-19 has challenged the global healthcare system through rapid proliferation and lack of existing treatment resulting in over 180 million cases and 3.8 million deaths since December 2019. Although pediatric patients only comprise 1-2% of diagnosed cases, their incidence of acute kidney injury ranges from 8.2% to 18.2% compared to 49% in adults. Severe infection, initiated by dysregulated host response, can lead to multiorgan failure. In this review, we focus on the use of various blood filters approved for use in pediatric kidney replacement therapy to mitigate adverse effects of severe illness. Therapeutic effects of these blood filters range from cytokine removal (CytoSorb, HA330, HCO/MCO), endotoxin removal (Toraymyxin, CPFA), both cytokine and endotoxin removal (oXiris), and non-specific removal of proteins (PMMA) that have already been established and can be used to mitigate the various effects of the cytokine storm syndrome in COVID-19.

Whole Exome Sequencing in a Population With Severe Congenital Anomalies of Kidney and Urinary Tract

Fetal and neonatal interventions (e.g., amnioinfusions, amniotic shunting, and infant dialysis) have increased survival of infants with severe Congenital Anomalies of the Kidney and Urinary Tract (CAKUT), however, outcomes vary dramatically. Our aim was to perform Whole Exome Sequencing (WES) in a unique severe CAKUT population with the goal to identify new variants that will enhance prediction of postnatal outcomes. We performed trio WES on five infants with severe CAKUT (undergoing fetal interventions and/or those who initiated renal replacement therapy (RRT) within 1 month of life) and their parents as well as three singletons. We identified three potential candidate gene variants (NSUN7, MTMR3, CEP162) and validated two variants in known CAKUT genes (GATA3 and FRAS1) showing strong enrichment in this severe phenotype population. Based on our small pilot study of a unique severe CAKUT population, WES appears to be a potential tool to help predict the course of infants with severe CAKUT prenatally.

In vitro measurements of ultrafiltration precision in hemofiltration and hemodialysis devices used in infants

BACKGROUND

To determine in vitro whether infant hemofiltration and hemodialysis devices can reliably deliver precise ultrafiltration (UF) control.

METHODS

We tested the Prismaflex, Aquarius and NIDUS devices which have different circuit types, by in vitro testing with a bag of saline set up as a dummy patient, and monitoring fluid shifts by precise weighing. We looked for differences between the UF rates set and achieved and between the UF result the device displays to the clinician and the true volumes removed, which may lead to clinical errors. We performed short studies at UF settings of zero and 40 ml/h, and with and without simulating poor withdrawal and return lines, and simulated a 4-h treatment session.

RESULTS

The Prismaflex setting vs actual errors and display vs actual errors had wide variances, with SDs of 4.1 and 14.0 ml by 15 min, respectively, at both zero and 40 ml/h UF settings. The Aquarius values were wider at 17.3 and 30.3 ml, respectively. For the NIDUS, the mean UF errors were close to zero, and the variances were 0.17 ml. Stop-alarms induced by an obstructed line produced extra UF errors of up to 0.2 ml. A limitation was that we used crystalloid and not colloid for these tests.

CONCLUSIONS

Hemotherapy devices with conventional circuits available in the UK do not regulate UF control sufficiently well to recommend for use in small infants, but the NIDUS volumetrically controlled circuit does. All hemotherapy devices intended for small infants should be tested for UF precision. We were unable to test the CARPEDIEM or Aquadex devices. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

Controversies in paediatric acute kidney injury and continuous renal replacement therapy: can paediatric care lead the way to precision acute kidney injury medicine?

PURPOSE OF REVIEW

Paediatric patients represent a unique challenge for providers managing acute kidney injury (AKI). Critical care for these children requires a precise approach to assessment, diagnostics and management.

RECENT FINDINGS

Primarily based on observational data, large epidemiologic datasets have demonstrated a strong association between AKI prevalence (one in four critically ill children) and poor patient outcome. Drivers of AKI itself are multifactorial and the causal links between AKI and host injury remain incompletely defined, creating a management paradigm primarily supportive in nature. The previous decades of research have focused primarily on elucidating the population-level epidemiologic signal of AKI and use of renal replacement therapy (RRT), but in order to reverse the course of the AKI 'epidemic', future decades will require more attention to the individual patient. A patient-level approach to AKI in children will require sophisticated approaches to risk stratification, diagnostics and targeted utilization of therapies (both supportive and targeted towards drivers of injury).

SUMMARY

In this review, we will summarize the past, present and future of AKI care in children, discussing the ongoing work and future goals of a personalized approach to AKI medicine.

Small tunneled central venous catheters as an alternative to a standard hemodialysis catheter in neonatal patients

BACKGROUND/PURPOSE

Continuous renal replacement therapy (CRRT) is difficult in neonates for several reasons, including problems with catheter placement and maintenance. We sought to compare outcomes between standard hemodialysis catheters (HDC) and 6Fr-tunneled central venous catheters (TC-6Fr).

METHODS

We evaluated neonates who received CRRT from December 2013 - January 2018. All patients received CRRT with the Aquadex (Baxter Corporation, Minneapolis, Minnesota) circuit. Data regarding patient demographics, CRRT indication, catheter days, reason for removal, and catheter-specific complications were analyzed.

RESULTS

Forty-six catheters were placed in 26 neonates; nine of these were 6Fr-tunneled catheters. The median age and mean weight at CRRT initiation was 9.5 days (IQR 4-31) and 3.5 kg (+/- 0.6 kg), respectively. TC-6Fr lasted longer (median of 28 days vs 10 days, p = 0.02), required fewer revisions (0 vs 0.16/10 catheter days) and were less commonly removed due to bleeding complications (0% vs 10.8%), occlusion (11.1% vs 18.9%), or malposition (0% vs 8.1%); none of these differences were statistically significant. TC-6Fr were associated with higher infection rates (33.3% vs 0%, p = 0.01) than HDC.

CONCLUSIONS

TC-6Fr use resulted in less need for catheter revisions and provided longer-lasting vascular access, which may influence infection rates. This catheter provides neonates in need of CRRT more reliable vascular access.

LEVEL OF EVIDENCE

III.

Acute pediatric kidney replacement therapies in Europe: demographic results from the EurAKId Registry

BACKGROUND

Acute kidney injury (AKI), particularly that requiring dialysis, is a severe complication in hospitalized children associated with high morbidity and mortality. A prospective European AKI registry (EurAKId registry, NCT02960867) was created to describe the epidemiology and outcomes of pediatric patients treated with acute dialysis.

METHODS

Children were recruited who were between 0 and 18 years of age and were treated both in and outside the Pediatric Intensive Care Unit (PICU) with peritoneal dialysis (PD), hemodialysis (HD) or continuous kidney replacement therapy (CKRT) for AKI or metabolic derangement, fluid overload (FO), sepsis, or respiratory distress. Five age groups and 12 categories of primary diseases were defined.

RESULTS

Data on 340 patients were analyzed, of whom 86% received dialysis for AKI and 14% for reasons other than AKI. Boys accounted for 60% of the patients. Illness severity was greater in children with cardiac and hematologic diseases than those with kidney diseases. Most patients received dialysis in the PICU (84%). The most frequently used dialysis modality was CKRT (64%), followed by PD (14%) and HD (14%). The overall survival rate was 65%. Survival was significantly lower in children with three comorbidities than in children with no comorbidities (41% and 83%, p < 0.001).

CONCLUSIONS

The EurAKId registry is the first prospective registry considering pediatric acute kidney replacement therapies (KRT) in both critical and non-critical care settings, focusing on the three dialysis modalities in Europe. The clinical indications for KRT have expanded; our population was characterized by critically ill patients, primarily boys, who frequently received dialysis in the PICU with CKRT.

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.

Fluid management, electrolytes imbalance and renal management in neonates with neonatal encephalopathy treated with hypothermia

Kidney dysfunction and acute kidney injury (AKI) frequently accompanies neonatal encephalopathy and contributes to neonatal morbidity and mortality. While there are currently no proven therapies for the treatment of AKI, understanding the pathophysiology along with early recognition and treatment of alterations in fluid, electrolyte and metabolic homeostasis that accompany AKI offer opportunity to reduce associated morbidity. Promising new tests and technologies, including urine and serum biomarkers and renal near-infrared spectroscopy offer opportunities to improve diagnosis and monitoring of neonates at risk for kidney injury. Furthermore, recent advances in neonatal kidney supportive therapies such as hemofiltration and hemodialysis may further improve outcomes in this population. This chapter provides an overview of disorders of fluid balance, electrolyte homeostasis and kidney function associated with neonatal encephalopathy and therapeutic hypothermia. Recommendations for fluid and electrolyte management based upon published literature and authors' opinions are provided.

Hemodynamic disturbances and oliguria during continuous kidney replacement therapy in critically ill children

BACKGROUND

About 1.5% of patients admitted to the Pediatric Intensive Care Unit (PICU) will require continuous kidney replacement therapy (CKRT)/renal replacement therapy (CRRT). Mortality of these patients ranges from 30 to 60%. CKRT-related hypotension (CKRT-RHI) can occur in 19-45% of patients. Oliguria after onset of CKRT is also common, but to date has not been addressed directly in the scientific literature.

METHODS

A prospective observational study was conducted to define factors involved in the hemodynamic changes that take place during the first hours of CKRT, and their relationship with urinary output.

RESULTS

Twenty-five patients who were admitted to a single-center PICU requiring CKRT between January 1, 2014, and December 31, 2018, were included, of whom 56.3% developed CKRT-RHI. This drop in blood pressure was transient and rapidly restored to baseline, and significantly improved after the third hour of CKRT, as core temperature and heart rate decreased. Urine output significantly decreased after starting CKRT, and 72% of patients were oliguric after 6 h of therapy. Duration of CKRT was significantly longer in patients presenting with oliguria than in non-oliguric patients (28.7 vs. 7.9 days, p = 0.013).

CONCLUSIONS

The initiation of CKRT caused hemodynamic instability immediately after initial connection in most patients, but had a beneficial effect on the patient's hemodynamic status after 3 h of therapy, presumably owing to decreases in body temperature and heart rate. Urine output significantly decreased in all patients and was not related to negative fluid balance, patient's hemodynamic status, CKRT settings, or kidney function parameters.

Kidney support therapy in the pediatric patient: Unique considerations for a unique population

The use of kidney support therapy (KST) for use in managing patients with acute kidney injury (AKI) has expanded greatly in the last several decades. The growing use of KST modalities in children, and now in neonates, has been associated with opportunities for education, clinical research, clinical practice improvements, and outcomes research. A multitude of controversies exist in the field of pediatric KST-many of which are shared by adult critical care nephrology practice. Simultaneously, pediatric KST has led the way to a burgeoning exploration of the importance of fluid overload as it relates to KST initiation and management and also with quality improvement. In this review, we will explore and describe the paradigms contained with pediatric KST used to support children with AKI. In addition to the governing principles related to the mechanics of KST, we will describe the novel aspects of newer support machines and ethical considerations of KST provision. Anticoagulation, dose, and modality will be discussed as well as priming procedures for special considerations. The utilization of KST across pediatric populations represents the next frontier of critical care nephrology.

Review: Neonatal dialysis is technically feasible but ethical and global issues need to be addressed

AIM

Our aim was to look at the technical, ethical and global issues related to neonatal dialysis.

METHODS

We performed a PubMed research on manuscripts published from March 2010 to March 2020 and retrospectively reviewed all neonates who received dialysis in our French paediatric and neonatal intensive care units from April 2009 to March 2019.

RESULTS

Dialysis is performed on neonates with pre-existing renal diseases, acute kidney injuries or inborn errors of metabolism. It is required in 0.5%-1% of neonates admitted to the neonatal intensive care units. Peritoneal dialysis and extracorporeal blood purification are both feasible, with more complications, but the results are close to those obtained in older infants, at least in children without multi-organ dysfunction. Novel haemodialysis machines are being evaluated. Ethical issues are a major concern. Multidisciplinary teams should consider associated comorbidities, risks of permanent end-stage renal disease and provide parents with full and neutral information. These should drive decisions about whether dialysis is in child's best interests.

CONCLUSION

Neonatal dialysis is technically feasible, but ethically challenging, and short-term and long-term data remain limited. Prospective studies and dialysis registries would improve global management and quality of life of these patients at risk of chronic kidney disease.

Improving the quality of neonatal acute kidney injury care: neonatal-specific response to the 22nd Acute Disease Quality Initiative (ADQI) conference

With the adoption of standardized neonatal acute kidney injury (AKI) definitions over the past decade and the concomitant surge in research studies, the epidemiology of and risk factors for neonatal AKI have become much better understood. Thus, there is now a need to focus on strategies designed to improve AKI care processes with the goal of reducing the morbidity and mortality associated with neonatal AKI. The 22nd Acute Dialysis/Disease Quality Improvement (ADQI) report provides a framework for such quality improvement in adults at risk for AKI and its sequelae. While many of the concepts can be translated to neonates, there are a number of specific nuances which differ in neonatal AKI care. A group of experts in pediatric nephrology and neonatology came together to provide neonatal-specific responses to each of the 22nd ADQI consensus statements.

I-KID study protocol: evaluation of efficacy, outcomes and safety of a new infant haemodialysis and ultrafiltration machine in clinical use: a randomised clinical investigation using a cluster stepped-wedge design

INTRODUCTION

The I-KID study aims to determine the clinical efficacy, outcomes and safety of a novel non-CE-marked infant haemodialysis machine, the Newcastle Infant Dialysis Ultrafiltration System (NIDUS), compared with currently available therapy in the UK. NIDUS is specifically designed for renal replacement therapy in small babies between 0.8 and 8 kg.

METHODS AND ANALYSIS

The clinical investigation is taking place in six UK centres. This is a randomised clinical investigation using a cluster stepped-wedge design. The study aims to recruit 95 babies requiring renal replacement therapy in paediatric intensive care units over 20 months.

ETHICS AND DISSEMINATION

The study has high parent and public involvement at all stages in its design and parents will be involved in dissemination of results to parents and professionals via publications, conference proceedings and newsletters. The study has has ethics permissions from Tyne and Wear South Research Ethics Committee.

TRIAL REGISTRATION NUMBERS

IRAS ID number: 170 481MHRA Reference: CI/2017/0066ISRCT Number: 13 787 486CPMS ID number: 36 558NHS REC reference: 16/NE/0008Eudamed number: CIV-GB-18-02-023105Link to full protocol v6.0: https://fundingawards.nihr.ac.uk/award/14/23/26.

Advances in Kidney Replacement Therapy in Infants

Acute kidney injury continues to be a highly occurring disease in the intensive care unit, specifically affecting up to a third of critically ill neonates as per various studies. Although first-line treatments of acute kidney injury are noninvasive, kidney replacement therapy (KRT) is indicated when conservative management modes fail. There are various modalities of KRT which can be used for neonatal populations, including peritoneal dialysis, hemodialysis, and continuous KRT. However, these KRT modalities present their own challenges in this specific patient population Thus, it is the aim of this review to introduce each of these KRT modalities in terms of their challenges, advances, and future directions, with specific emphasis on new technology including the Cardio-Renal Pediatric Emergency Dialysis Machine, Newcastle infant dialysis and ultrafiltration system, and the Aquadex system for ultrafiltration.

Continuous kidney replacement therapy in critically ill neonates and infants: a retrospective analysis of clinical results with a dedicated device

BACKGROUND

Providing extracorporeal renal support to neonates and infants involves a number of technical and clinical issues, possibly discouraging early utilization. This report aims to describe a multicenter experience of continuous kidney replacement therapy (CKRT) delivery to small infants using a device specifically designed for this age group.

METHODS

A retrospective cohort analysis of all patients treated with the Carpediem™ machine (Bellco-Medtronic, Mirandola, Italy) in 6 centers between June 2013 and December 2016.

RESULTS

Twenty-six neonates and small infants received 165 CKRT sessions in convective modality. Median age at neonatal intensive care unit admission 1 day (IQR 1-11), median body weight 2.9 kg (IQR 2.2-3.6). Median circuit duration 14 h (IQR 10-22), with delivered/prescribed time ratio of 84%. CKRT was conducted using 4 Fr (27%), 5 Fr (35%), 6.5 Fr (11%), and 7 Fr (3%) vascular access, and with umbilical and peripheral accesses (11% each) allowing overall median blood flow of 4.5 ml/kg/min (IQR 3.4-6) and median effluent flow rate 35 ml/kg/h (IQR 28-42). Circuits were primed with normal saline in 58% of treatments, colloids in 31%, and packed red blood cells in 11%. No serious adverse events directly related to machine application were reported by any center. Twenty-five (96%) patients survived their CKRT course and 13 patients (50%) survived to ICU discharge.

CONCLUSIONS

CKRT in neonates was easy to initiate and conduct when performed with small central vascular accesses coupled with this device. A dedicated technology for infant CKRT delivery enables patients to be safely treated avoiding technical complications. Graphical abstract.

Renal Replacement Therapy in Neonates

Acute kidney injury (AKI) is a highly prevalent disease entity in the NICU, affecting nearly one-quarter of critically ill neonates by some reports. Though medical management remains the mainstay in the treatment of AKI, renal replacement therapy (RRT) is indicated when conservative measures are unable to maintain electrolytes, fluid balance, toxins, or waste products within a safe margin. Several modalities of RRT exist for use in neonatal populations, including peritoneal dialysis, hemodialysis, and continuous RRT. It is the aim of this review to introduce each of these RRT modalities, as well as to discuss their technical considerations, benefits, indications, contraindications, and complications.

Serial Amnioinfusion as Regenerative Therapy for Pulmonary Hypoplasia in Fetuses With Intrauterine Renal Failure or Severe Renal Anomalies: Systematic Review and Future Perspectives

The aim of this study was to investigate the effect of serial amnioinfusion therapy (SAT) for pulmonary hypoplasia in lower urinary tract obstruction (LUTO) or congenital renal anomalies (CRAs), introduce patient selection criteria, and present a case of SAT in bilateral renal agenesis. We conducted a search of the MEDLINE, EMBASE, Web of Science, and Scopus databases for articles published from database inception to November 10, 2017. Eight studies with 17 patients (7 LUTO, 8 CRA, and 2 LUTO + CRA) were included in the study. The median age of the mothers was 31 years (N=9; interquartile range [IQR], 29-33.5 years), the number of amnioinfusions was 7 (N=17; IQR, 4.5-21), gestational age at first amnioinfusion was 23 weeks and 4 days (N=17; IQR, 21-24.07), gestational age at delivery was 32 weeks and 2 days (N=17; IQR, 30 weeks to 35 weeks and 6.5 days), birthweight of newborns was 3.7 kg (N= 9; IQR, 2.7-3.7 kg), Apgar score at 1 minute was 2.5 (N=8; IQR, 1-6.5), and Apgar score at 5 minutes was 5.5 (N=8; IQR, 0-7.75). In conclusion, SAT may provide fetal pulmonary palliation by reducing the risk of newborn pulmonary compromise secondary to oligohydramnios. Multidisciplinary research efforts are required to further inform treatment and counseling guidelines. We propose a multidisciplinary approach to prenatal classification of fetuses with LUTO to inform patient selection.

Dialysis modalities for the management of pediatric acute kidney injury

Acute kidney injury (AKI) is an increasingly frequent complication among hospitalized children. It is associated with high morbidity and mortality, especially in neonates and children requiring dialysis. The different renal replacement therapy (RRT) options for AKI have expanded from peritoneal dialysis (PD) and intermittent hemodialysis (HD) to continuous RRT (CRRT) and hybrid modalities. Recent advances in the provision of RRT in children allow a higher standard of care for increasingly ill and young patients. In the absence of evidence indicating better survival with any dialysis method, the most appropriate dialysis choice for children with AKI is based on the patient's characteristics, on dialytic modality performance, and on the institutional resources and local practice. In this review, the available dialysis modalities for pediatric AKI will be discussed, focusing on indications, advantages, and limitations of each of them.

Acute Kidney Injury and Fluid Overload in Pediatric Cardiac Surgery

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Aquapheresis (AQ) in Tandem with Extracorporeal Membrane Oxygenation (ECMO) in Pediatric Patients

Children with cardiopulmonary failure requiring extracorporeal membrane oxygenation (ECMO) are at risk for fluid overload (FO) despite the normal estimated glomerular filtration rate (eGFR). It has been shown that survival in the intensive care unit (ICU) is inversely proportional to FO. Therefore, fluid removal, or prevention of FO, in these critical cases has the potential to improve survival. Aquapheresis (AQ), a procedure used for fluid removal, with success in patients with heart failure has also been used in children with acute oliguric kidney injury (AKI), to prevent and treat FO. The purpose of this article was to describe the use of Aquadex FlexFlow^® for AQ in pediatric patients on ECMO, as a means to provide a simplified and safe form of fluid removal with minimal impact on ECMO therapy. The principal variables collected include patients' demographics, urine output, serum creatinine, withdrawal and infusion pressures, ultrafiltration (UF) rates, and ECMO flow ranges, along with length of stay in pediatric ICU and survival. Patient survival was 100% with preserved eGFR. The ECMO flows were not affected by AQ. Urine output decreased somewhat during therapy, with little AQ machine pressure variations. Range of UF tolerated without hemodynamic abnormalities was 1.24-6.2 mL/kg/h, allowing the patients to maintain their pre-AQ body weight, while receiving intravenous (IV) nutrition and medications. This article describes the use of AQ in tandem with ECMO in a user-friendly and safe way to provide UF in children requiring cardiopulmonary support, with minimal flow and hemodynamic disturbance.

Kidney Support in Children using an Ultrafiltration Device: A Multicenter, Retrospective Study

BACKGROUND AND OBJECTIVES

Provision of kidney replacement therapy (KRT) to manage kidney injury and volume overload in critically ill neonates and small children is technically challenging. The use of machines designed for adult-sized patients, necessitates large catheters, a high extracorporeal volume relative to patient size, and need for blood priming. The Aquadex FlexFlow System (CHF Solutions Inc., Eden Prairie, MN) is an ultrafiltration device designed for fluid removal in adults with diuretic resistant heart failure. It has an extracorporeal volume of 33 ml, which can potentially mitigate some complications seen at onset of KRT in smaller infants.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this multicenter, retrospective case series of children who received KRT with an ultrafiltration device (n=119 admissions, 884 circuits), we report demographics, circuit characteristics, complications, and short- and long-term outcomes. Patients were grouped according to weight (<10, 10-20, and >20 kg), and received one of three modalities: slow continuous ultrafiltration, continuous venovenous hemofiltration (CVVH), or prolonged intermittent KRT. Our primary outcome was survival to end of KRT.

RESULTS

Treatment patterns and outcomes varied between the groups. In patients who weighed <10 kg, the primary indication was AKI in 40%, volume overload in 46%, and ESKD in 14%. These patients primarily received CVVH (66%, n=48) and prolonged intermittent KRT (21%, n=15). In the group weighing >20 kg, volume overload was the primary indication in 91% and slow continuous ultrafiltration was the most common modality. Patients <10 kg had lower KRT survival than those >20 kg (60% versus 97%), more volume overload at onset, and received KRT for a longer duration. Cardiovascular complications at initiation were seen in 3% of treatments and none were severe. Complications during therapy were seen in 15% treatments and most were vascular access-related.

CONCLUSIONS

We report the first pediatric experience using an ultrafiltration device to provide a range of therapies, including CVVH, prolonged intermittent KRT, and slow continuous ultrafiltration. We were able to initiate KRT with minimal complications, particularly in critically ill neonates. There is an unmet need for devices specifically designed for younger patients. Having size-appropriate machines will improve the care of smaller children who require kidney support.

Secular Trends in Incidence, Modality and Mortality with Dialysis Receiving AKI in Children in Ontario: A Population-Based Cohort Study

BACKGROUND AND OBJECTIVES

There is a limited appreciation of the epidemiology of dialysis-receiving AKI in children. The primary objective of the study was to evaluate changes in the incidence of dialysis-receiving AKI among children over a period of 20 years in Ontario, Canada. The secondary objectives were to assess temporal trends in the utilization of various dialysis modalities and 30-day mortality among children with dialysis-receiving AKI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All children (29 days to 18 years) who received their first dialysis for AKI between 1996 and 2015 were identified from healthcare administrative databases. Those who received dialysis for ESKD, inborn errors of metabolism, and poisonings were excluded. The incidence rates of dialysis-receiving AKI were reported annually. The Cochran-Armitage test was used to assess trends in the incidence and short-term mortality after dialysis-receiving AKI.

RESULTS

We identified 1394 children treated with dialysis for AKI during a hospital stay. There was a significant increase in the incidence of dialysis-receiving AKI among hospitalized children from 1996 (0.58 per 1000 person-years) to 2015 (0.65 per 1000 person-years) (P=0.01). The use of continuous kidney replacement therapy and intermittent hemodialysis increased whereas the relative use of peritoneal dialysis declined over time. Thirty-day mortality rates after dialysis-receiving AKI increased from 14% to 25% between 1996 and 2009 and reduced to 19% in the more recent years (P=0.03).

CONCLUSIONS

In Ontario, the incidence of dialysis-receiving AKI among children has increased between 1996 and 2015. The use of peritoneal dialysis for AKI has declined and the short-term mortality after dialysis-receiving AKI has increased.

In Vitro Evaluation of Resistance and Warming Performance of a Small Blood Warmer on a Continuous Renal Replacement Therapy Circuit

Children on extracorporeal devices are at increased risk of hypothermia and require circuits with lower extracorporeal volume to avoid blood priming. We performed an in vitro study of the enFlow blood warmer to assess its warming performance and impact on circuit resistance at a high blood flow rate. The enFlow was added on the return line of a continuous renal replacement therapy circuit in a closed circuit primed with expired packed red blood cells (40% Hct). Return venous pressure and temperature pre- and post- both enFlow and Prismaflo II were measured at varying blood flow with different combination of the two blood warmers. Each variable was recorded eight times over 2 min. Return venous pressure was higher with the enFlow but was still within clinically usable range (127.5 ± 4.6 vs. 45.3 ± 1.4 mm Hg at 200 mL/min, P < 0.05). The enFlow was able to achieve post-warmer temperature between 34.1 and 35.2°C even at 200 mL/min with blood, lower than what was observed with crystalloid, but still more effective than the Prismaflo II (P < 0.05 vs. enFlow post-warmer temperature) achieving between 32.8 and 34.0°C. Combining both warmers achieved a higher post-warmer temperature between 35.1 and 36.5°C. The enFlow can warm blood at high flow rates with minimal extracorporeal volume increase (~5 mL) and improve hypothermia prevention but may have resistance issues at the highest flows. The use of this device could benefit pediatric practice where smaller extracorporeal volumes are needed and patients are at increased risk of hypothermia.

Choice of Catheter Size for Infants in Continuous Renal Replacement Therapy: Bigger Is Not Always Better

OBJECTIVES

Renal replacement therapy in infants and small children is the treatment of choice for severe oligoanuric renal dysfunction, with an increasing consensus that early initiation might contribute to preventing acute kidney injury complications. Safer renal replacement therapy devices specifically designed for neonates may contribute to ameliorating outcomes and increasing chances of survival. One of the crucial factors to achieve an effective renal replacement therapy in small infants is adequate vascular access. The interaction of small size central vascular catheters with renal replacement therapy devices has never been investigated. The aim of this study was to characterize both the operating conditions and performance of three different central vascular catheters sizes (4F, 5F, and 7F) connected to two different extracorporeal blood circulation models (adult and pediatric). The rheologic performance of each vascular access size in combination with the adult and pediatric renal replacement therapy models was described.

DESIGN

Series of experimental extracorporeal circulation circuit tests were conducted with different setups. A two-roller pump was used to simulate a standard adult dialysis machine, whereas a small three-roller pump served as pediatric renal replacement therapy device.

SETTING

A pressure-flow setup aimed to collect pressure and flow values under different test conditions. A second experiment focused on hemolysis estimation induced by the extracorporeal system. Hemolysis exclusively induced by the 4F catheter was also evaluated. Finally, our data were applied to estimate the optimal catheter size theoretically capable of delivering adequate doses basing on anthropometric data (patient weight and cannulation site) in absence of direct ultrasound vessel measurement.

SUBJECTS

In vitro tests conducted on simulated extracorporeal circuit models of continuous pediatric and neonatal renal replacement therapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

When 4F and 5F catheters are used, maximal blood flows within safe circuit pressures can be set at the values of 13 and 29 mL/min, respectively, when a small pump is used. Differently, when using adult roller pumps, only maximal flows of 10 and 20 mL/min are reached. However, hemolysis is higher when using a three-roller pump compared with the two-roller. The clinical impact of this increased hemolytic burden is likely not relevant.

CONCLUSIONS

Small size central vascular catheters display optimal rheologic performances in terms of pressures and flows particularly when the renal replacement therapy device is equipped with pumps proportional to central vascular catheters sizes, and even when relatively high blood flows are set. This is achieved at the risk of a higher hemolysis rate.

Renal replacement therapy in neonates with an inborn error of metabolism

Hyperammonemia can be caused by several genetic inborn errors of metabolism including urea cycle defects, organic acidemias, fatty acid oxidation defects, and certain disorders of amino acid metabolism. High levels of ammonia are extremely neurotoxic, leading to astrocyte swelling, brain edema, coma, severe disability, and even death. Thus, emergency treatment for hyperammonemia must be initiated before a precise diagnosis is established. In neonates with hyperammonemia caused by an inborn error of metabolism, a few studies have suggested that peritoneal dialysis, intermittent hemodialysis, and continuous renal replacement therapy (RRT) are effective modalities for decreasing the plasma level of ammonia. In this review, we discuss the current literature related to the use of RRT for treating neonates with hyperammonemia caused by an inborn error of metabolism, including optimal prescriptions, prognosis, and outcomes. We also review the literature on new technologies and instrumentation for RRT in neonates