Novel Use of an Ultrafiltration Device as an Alternative Method for Fluid Removal in Critically Ill Pediatric Patients with Cardiac Disease: A Case Series

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.

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.

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.

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.

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.