Management of fluid balance in CRRT: a technical approach

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.

Acute kidney injury and continuous renal replacement therapy: A nursing perspective for my shift today in the intensive care unit

Handover, clinical discussion, and care for patients in the Intensive Care Unit (ICU) require visual cues to a verbal "story" in an attempt to quickly understand the patient status. Continuous renal replacement therapy (CRRT) is often associated with sepsis or a toxic cause and "kidney attack" not apparent to the patient; "silent" with no pain, discomfort, or vital sign changes initially. Language, terminology, and definitions for this acute kidney injury (AKI) are a graded classification with guidelines. CRRT and dialysis techniques use the physiological principles of diffusion and or convection for solute removal providing a replacement for the basic kidney functions to sustain life until function returns. When to stop CRRT is based on clinical assessment of the patient overall status and urine production re-starting. The medical treatment is focused on the key interventions of resuscitation, remove the cause, support with CRRT or dialysis and monitor for recovery of function. CRRT requires a multidisciplinary team and quality process, local policies, education, and competency pathways to promote best outcomes and efficacy.

ACUsmart Continuous Renal Replacement Therapy Platform: Multicenter Pilot Study for Technical and Clinical Assessment (A.M.P. Study)

BACKGROUND

ACUsmart (Medica S.P.A., Italy) is a new-generation, continuous renal replacement therapy (CRRT) machine for critically ill patients with acute kidney injury. We designed a multicenter international pilot study to provide a description of outlines of the ACUsmart system, evaluation aspects of functionality, usability, and feasibility, discriminating reasons of possible treatment's withdrawals or discontinuations and highlighting strong and weak points of the machine.

METHODS

Data of 23 CRRT (and 11 plasma exchange) treatments were collected from 4 intensive care units. Parameters such as treatment duration, downtime, delivered dose, and number and type of alarms were recorded. The general perception of the machine was quantified through the administration of a survey to each component of the evaluating staff.

RESULTS

A total treatment time of 447 h was carried with ACUsmart. Eleven continuous veno-venous hemofiltration, 4 continuous veno-venous hemodialysis , and 8 continuous veno-venous hemodiafiltration were performed. The average percentage of net treatment duration with respect to total treatment duration was 92.37%. The mean prescribed dose and delivered dose were 26.33 and 24.10 mL/kg/h, respectively. In general, the machine was rated by users involved as practical and easy to use, although few components need to be slightly improved.

CONCLUSION

ACUsmart is a new multifunctional machine that meets most of the features required in a fourth-generation CRRT equipment.

Volume Management by Renal Replacement Therapy in Acute Kidney Injury

Management of fluid balance is one of the basic but vital tasks in the care of critically ill patients. Hypovolemia results in a decrease in cardiac output and tissue perfusion and may lead to progressive multiple organ dysfunction, including the development of acute renal injury (AKI). However, in an effort to reverse pre-renal oliguria, it is not uncommon for patients with established oliguric acute renal failure, particularly when associated with sepsis, to receive excessive fluid resuscitation, leading to fluid overload. In patients with established oliguria, renal replacement therapy may be required to treat hypervolemia. Safe prescription of fluid loss during RRT requires intimate knowledge of the patient's underlying condition, understanding of the process of ultrafiltration and close monitoring of the patient's cardiovascular response to fluid removal. To preserve tissue perfusion in patients with AKI, it is important that RRT be prescribed in a way that optimizes fluid balance by removing fluid without compromising the effective circulating fluid volume. In patients who are clinically fluid overloaded, it is equally important that the amount of fluid removed be as exact as possible. Fluid balance errors can occur as a result of inappropriate prescription, operator error or machine error. Some CRRT machines have potential for significant fluid errors if alarms can be overridden. Threshold values for fluid balance error have been developed which can be used to predict the severity of harm. It is important that RRT education programs emphasize the risk associated with fluid balance errors and with overriding machine alarms.

Management of Fluid Balance in Continuous Renal Replacement Therapy: Technical Evaluation in the Pediatric Setting

Fluid overload control and fluid balance management represent very important factors in critically ill children requiring renal replacement therapy A relatively high fluid volume administration in children and neonates is often necessary to deliver adequate amounts of blood derivatives, vasopressors, antibiotics, and parenteral nutrition. Fluid balance errors during pediatric continuous renal replacement therapy (CRRT) might significantly impact therapy delivery and have been described as potentially lethal. The aim of this study was to evaluate the accuracy of delivered vs. prescribed net ultrafiltration (UF) during CRRT applied to 2 neonates and 2 small children, either as dialytic treatment alone or during extracorporeal membrane oxygenation (ECMO). In accordance with an Acute Dialysis Quality Initiative workgroup statement, net UF was defined as the “overall amount of fluid extracted from the patient in a given time”. Mean prescribed net UF was 18.5 ml/h (SD=6.7) during neonatal treatments and 70.3 ml/h (SD=22.5) during CRRT in small children. Daily net UF ranged from 200 mL to about 600 mL in the 2 neonates and from 1,200 to 1800 mL in the 2 children. The percentage error of delivered net UF ranged from −1.6% to 5.8% of the prescribed level. The mean error of the ECMO/CRRT patients was 3.024 ml/h vs. 0.45 m/h for the CRRT patients (p<0.001). The same difference was not evident when the 2 neonates were compared with the 2 small children (without considering the presence of ECMO). CRRT and net UF delivery appeared to be accurate, safe, and effective in this small cohort of high-risk pediatric patients.

Fluid Balance Error in Continuous Renal Replacement Therapy: A Technical Note

Background.

The reliability and safety of continuous renal replacement therapy (CRRT) machines have improved, yet there still remains the potential for fluid balance errors to occur during treatment.

Methods.

In vitro testing of two Kimal Hygieia CRRT machines (Plus and Ultima) was performed. Normal saline to simulate the blood circuit and standard bicarbonate-based fluid for replacement were used. All tests were performed in CVVH mode at four ultrafiltration (UF) rates. The testing was based on creation of a voluntary fluid balance error by clamping the line that fills the replacement fluid chamber to stop flow to the (simulated) patient. The time to alarms and fluid balance errors were recorded. The alarms were overridden and the accumulated fluid balance error allowed by the machine was determined.

Results.

The alarm occurred approximately 1 minute after the replacement fluid line was clamped at all UF rates. There was no limit to the number of times the alarm could be overridden and the accumulated negative fluid balance was proportional to the prescribed UF rate. After the replacement fluid chamber was allowed to re-fill, the machine attempted to correct the fluid deficit and consistently delivered excess fluid to generate a positive fluid balance error.

Conclusions.

The Hygieia machines appear designed with appropriate alarm and safety features. However, simulated fluid balance errors raise caution for operators. Clinicians and nurses need to understand the clinical implications of alarm overrides. Fluid balance errors caused by failure to acknowledge and correct replacement fluid failure alarms may cause harm to patients.

(R)evolution in the Management of Acute Kidney Injury in Newborns

The application of continuous renal replacement therapy (CRRT) in children, before roller pumps and dialysis monitors were available in the intensive care unit, was realized by continuous arteriovenous hemofiltration. Then hemofiltration was coupled with dialysis in order to increase dialytic dose and system efficiency, and the circuit and filters were specifically modified to optimize patency and session life span. After about 30 years, another revolution is ongoing, in that pediatric acute kidney injury (AKI) and fluid accumulation (for which critically ill newborns and children with multiple-organ dysfunction are greatly at risk) are recognized as independently associated with mortality and identified as primary conditions to prevent and aggressively treat. Today, novel technology specifically dedicated for very young patients will allow feasible and straightfoward application of CRRT to infants and children. This article discusses the authors' personal perspectives on how clinical and technical issues of dialysis in children have been addressed and how today, severe pediatric AKI can be managed with accurate and safe CRRT machines that will likely yield outcome improvements in the coming decades.

Pediatric continuous renal replacement: 20 years later

INTRODUCTION

More than 20 years have passed since the first clinical application of continuous renal replacement therapy (CRRT) in children. In that revolutionary era, before roller pumps and dialysis monitors for intensive care units were readily available, continuous arteriovenous hemofiltration was the most common treatment for critically ill children.

MAJOR FINDINGS

Those steps were the basis for current knowledge about modern CRRT. Research on circuit rheology and filter materials allowed for the improvement of materials, and the optimization of patency and session life spans. Hemofiltration was coupled with dialysis to increase dialytic dose and system efficiency. Several systems were required to optimize ultrafiltration and manage fluid overload. A quarter of a century later, another revolution is taking place. Acute renal failure has been recognized as a threatening syndrome, independently associated with mortality in critically ill children and characterized by a broad spectrum of clinical phenotypes. For this reason, it has been redefined as acute kidney injury (AKI). This condition is today accurately classified in both adults and children, and has been identified as a primary condition for prevention and aggressive treatment in all pediatric intensive care unit patients. Critically ill neonates and children with multiple organ dysfunction are certainly at higher risk of AKI. Finally, novel technology specifically dedicated to pediatric patients allows feasible and easy application of CRRT to infants and children: a new field of critical care nephrology, dedicated to pediatric patients, has been fully developed.

CONCLUSION

After 20 years, significant developments in critical care nephrology have taken place. Clinical and technical issues have both been addressed, and severe pediatric AKI can currently be managed with accurate and safe dialysis machines that will likely warrant outcome improvements over the following decade.

Renal replacement therapy in neonates

The incidence of acute kidney injury (AKI) has steadily increased in the last decade in neonates and infants. Despite the extensive proposed pharmacologic approaches to treat or prevent AKI, renal replacement therapy is the only available therapeutic approach to manage the consequences of significant AKI and maintain electrolyte homeostasis and fluid balance in infants with AKI. The objective of this article is to summarize the different approaches and modalities of renal replacement therapy in neonatal intensive care units.

Considerations in the critically ill ESRD patient

ESRD patients are admitted more frequently to intensive care units (ICUs) and have higher mortality risks than the general population, and the main causes of critical illness among ESRD patients are cardiovascular events, sepsis, and bleeding. Once in the ICU, hemodynamic stabilization and fluid-electrolyte management pose major challenges in oligoanuric patients. Selection of renal replacement therapy (RRT) modality is influenced by the outpatient modality and access, as well as severity of illness, renal provider experience, and ICU logistics. Currently, most patients receive intermittent hemodialysis or continuous RRT with temporary vascular access catheters. Acute peritoneal dialysis (PD) is less frequently utilized, and utility of outpatient PD is reduced after an ICU admission. Thus, preservation of current vascular accesses, while limiting venous system damage for future access creations, is relevant. Also, dosing of small-solute clearance with urea kinetic modeling is difficult and may be supplanted by novel online clearance techniques. Medication dosing, coordinated with delivered RRT, is essential for septic patients treated with antibiotics. A comprehensive, standardized approach by a multidisciplinary team of providers, including critical care specialists, nephrologists, and pharmacists, represents a nexus of care that can reduce readmission rates, morbidity, and mortality of vulnerable ESRD patients.

CA.R.PE.DI.E.M. (Cardio-Renal Pediatric Dialysis Emergency Machine): evolution of continuous renal replacement therapies in infants. A personal journey

Pedriatric acute kidney injury (AKI) is a well-described clinical syndrome that is characterized by a reduction of both the urine output and glomerular filtration rate. AKI in critically ill children is typically associated with multiple organ dysfunction. A dramatic increase in the incidence of AKI in pediatric intensive care units has been observed in the last 10 years. Unfortunately, the absence of sufficiently effective preventive and therapeutic measures at the present time has limited significant improvements in AKI care. Morality in patients with severe AKI remains unacceptably high (>50 %), with renal replacement therapy (RRT) remaining the most effective form of support for these patients. Despite technological advances during the last 10 years which have resulted in the development of the so-called "third-generation dialysis machines" that are characterized by the highest level of safety and accuracy, a truly pedriatric RRT system has never been developed. Consequently, dialysis/hemofiltration in critically ill children is currently performed by adapting adult systems to the much smaller pediatric patients. In particular, research in this field should focus on children weighing less than 10 kg for whom the delivery of RRT is a clinical and technological challenge. We describe here the evolution of pediatric RRT during the last 30 years and report in detail on the CARPEDIEM project, which has recently been established to finally provide neonates and infants with a reliable dialysis machine that is specifically designed for this age group.

Technical advances in renal replacement therapy

Critically ill patients are subject to several risk factors for organ injury: surgical intervention, trauma, rhabdomyolysis, hemodynamic instability, organ hypoperfusion, bacteremia and endotoxemia, sepsis and septic shock. These conditions may cause acute kidney injury (AKI), myocardial dysfunction, liver failure, coagulation abnormalities, acute lung injury (ALI), adult respiratory distress syndrome (ARDS), bone marrow depression, loss of acid/base homeostasis, and finally, brain dysfunction. The resulting picture of multiple organ dysfunction syndrome (MODS) is a lethal clinical entity that is refractory to all therapies in the majority of cases. According to the "humoral theory of sepsis", soluble substances circulate in blood and participate in the generation of the different disorders of MODS; thus, AKI is not the only clinical disorder observed in intensive care unit (ICU) patients nor is it an isolated syndrome. Current extracorporeal management of such patients focuses mainly on renal replacement therapy (RRT). Nevertheless, in recent years, technical evolution of extracorporeal devices led to the potential creation of multiple organ support therapy (MOST) in order to provide a comprehensive replacement of multiorgan dysfunction: hence, other organs (liver, heart, lungs) and syndromes (abdominal sepsis, septic shock) can today be consistently supported and bridged. The technical advances of extracorporeal equipment, moreover, might allow today the design of a dedicated pediatric RRT device in order to treat patients below 10 kg, with the safety and adequacy standards that are currently granted to the adult population. This review will describe the technical evolution of MOST machines and current literature available on MOST.

Continuous renal replacement therapies: a brief primer for the neurointensivist

Continuous renal replacement therapy (CRRT) is a renal replacement modality that is often used in the ICU setting, including the neuro-ICU. This form of renal replacement therapy has been used classically for acute renal failure in patients with hemodynamic compromise, but is gaining acceptance as a method to control vascular and extra-vascular volume and mediate cytokines in non-renal diseases. Although these uses are briefly discussed, this review concentrates on the different forms of continuous renal replacement, mainly focusing on the technology of convective versus diffusive modalities and briefly on filter technology. There is also discussion on the various anticoagulation regimes used in CRRT including data on performing CRRT without anticoagulation. This review is not meant to be a discussion on the pros and cons of CRRT versus intermittent dialysis, but rather a primer on the technology of CRRT and how this therapy may affect general care of the ICU patient.

Volume management in continuous renal replacement therapy

Volume management is an integral component of the care of critically ill patients to maintain hemodynamic stability and optimize organ function. The dynamic nature of critical illness often necessitates volume resuscitation and contributes to fluid overload particularly in the presence of altered renal function. Diuretics are commonly used as an initial therapy to increase urine output; however they have limited effectiveness due to underlying acute kidney injury and other factors contributing to diuretic resistance. Continuous renal replacement techniques (CRRT) are often required for volume management. In this setting, successful volume management depends on an accurate assessment of fluid status, an adequate comprehension of the principles of fluid management with ultrafiltration, and clear treatment goals. Complications related to excessive ultrafiltration can occur and have serious consequences. A careful monitoring of fluid balance is therefore essential for all patients. This review provides an overview of the appropriate assessment and management of volume status in critically ill patients and its management with CRRT to optimize organ function and prevent complications of fluid overload.

Machines for continuous renal replacement therapy

A significant number of advancements have taken place since the beginning of continuous renal replacement therapy (CRRT). In particular, high volume hemofiltration and high permeability hemofiltration have been successful extensions of the technique. The additional and combined use of sorbent has also been tested successfully. Specific machines have now been designed to permit safe and reliable performance of the therapy. These new devices are equipped with a friendly user interface that allows for easy performance and monitoring. The apparent complexity of the circuit is made simple by a self-loading circuit or a cartridge which includes the filter and the blood and dialysate lines. Priming is performed automatically by the machine and pre- or postdilution (reinfusion of substitution fluid before or after the filter) can easily be performed by changing the position of the reinfusion line. These new machines permit all CRRT methodologies to be performed by programming the flows and the total amounts of fluid to be exchanged or circulated as a countercurrent dialysate at the beginning of the session. Progress has been made not only in technology in this area but also on our understanding of the pathophysiology of acute renal failure. New biomaterials and new devices are now available with new frontiers are on the horizon. We might, however, speculate that although improvements have been made, a lot remains to be done. There is no doubt that technology has progressed enormously in critical care nephrology and that more progress will come in the near future. The goal, and likely outcome, is an improvement in the morbidity and mortality of the most severely ill patients.

Continuous Peritoneal Dialysis Compared with Daily Hemodialysis in Patients with Acute Kidney Injury

Background

In some parts of the world, peritoneal dialysis is widely used for renal replacement therapy (RRT) in acute kidney injury (AKI), despite concerns about its inadequacy. It has been replaced in recent years by hemodialysis and, most recently, by continuous venovenous therapies. We performed a prospective study to determine the effect of continuous peritoneal dialysis (CPD), as compared with daily hemodialysis (dHD), on survival among patients with AKI.

Methods

A total of 120 patients with acute tubular necrosis (ATN) were assigned to receive CPD or dHD in a tertiary-care university hospital. The primary endpoint was hospital survival rate; renal function recovery and metabolic, acid–base, and fluid controls were secondary endpoints.

Results

Of the 120 patients, 60 were treated with CPD (G1) and 60 with dHD (G2). The two groups were similar at the start of RRT with respect to age (64.2 ± 19.8 years vs 62.5 ± 21.2 years), sex (men: 72% vs 66%), sepsis (42% vs 47%), shock (61% vs 63%), severity of AKI [Acute Tubular Necrosis Individual Severity Score (ATNISS): 0.68 ± 0.2 vs 0.66 ± 0.22; Acute Physiology and Chronic Health Evaluation (APACHE) II: 26.9 ± 8.9 vs 24.1 ± 8.2], pre-dialysis blood urea nitrogen [BUN (116.4 ± 33.6 mg/dL vs 112.6 ± 36.8 mg/dL)], and creatinine (5.85 ± 1.9 mg/dL vs 5.95 ± 1.4 mg/dL). In G1, weekly delivered Kt/V was 3.59 ± 0.61, and in G2, it was 4.76 ± 0.65 ( p < 0.01). The two groups were similar in metabolic and acid–base control (after 4 sessions, BUN < 55 mg/dL: 46 ± 18.7 mg/dL vs 52 ± 18.2 mg/dL; pH: 7.41 vs 7.38; bicarbonate: 22.8 ± 8.9 mEq/L vs 22.2 ± 7.1 mEq/L). Duration of therapy was longer in G2 (5.5 days vs 7.5 days; p = 0.02). Despite the delivery of different dialysis methods and doses, the survival rate did not differ between the groups (58% in G1 vs 52% in G2), and recovery of renal function was similar (28% vs 26%).

Conclusion

High doses of CPD provided appropriate metabolic and pH control, with a rate of survival and recovery of renal function similar to that seen with dHD. Therefore, CPD can be considered an alternative to other forms of RRT in AKI.

Renal replacement therapies: physiological review

INTRODUCTION

A physiological review on renal replacement therapies (RRT) is a challenging task: there is nothing "physiologic" about RRT, since the most accurate, safe and perfectly delivered extracorporeal therapy would still be far from "physiologically" replacing the function of the native kidney.

METHODS

This review will address the issues of physiology of fluid and solute removal, acid base control and impact on mortality during intermittent and continuous therapies: different RRT modalities and relative prescriptions will provide different "physiological clinical effects" to critically ill patients with acute kidney injury (AKI), with the aim of restoring lost "renal homeostasis". On the other side, however, the "pathophysiology" of RRT, consists with unwanted clinical effects caused by the same treatments, generally under-recognized by current literature but often encountered in clinical practice. Physiology and pathophysiology of different RRT modalities have been reviewed.

CONCLUSION

Physiology and pathophysiology of RRT often coexist during dialysis sessions. Improvement in renal recovery and survival from AKI will be achieved from optimization of therapy and increased awareness of potential benefits and dangers deriving from different RRT modalities.

Assessment of Current Continuous Hemofiltration Systems and Development of a Novel Accurate Fluid Management System for Use in Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) with a renal replacement therapy such as continuous venovenous hemofiltration (CVVH) provides life-saving temporary heart and lung, and renal support in pediatric and neonatal intensive care units. However, studies have shown that this approach may be hampered due to the potentially inaccurate fluid delivery∕drainage of current intravenous (IV) fluid pumps, creating potential for excessive fluid removal and undesired degrees of dehydration. We present a simple and novel accurate fluid management system capable of working against the high volume flow and pressures typically seen in patients on ECMO. The accuracy of the in-line system implemented at Children’s Healthcare of Atlanta at Egleston was assessed experimentally. The data assisted in the development of a novel automated and accurate fluid management system that functions based on a conservation of volume approach to limit the inaccuracies observed in typical clinical implementations of CVVH. IV pump accuracy measurements demonstrated a standard error in net ultrafiltrate volume removed from the patient of up to 848.5±156ml over a period of 24h, supporting previous observations of patient’s dehydration during the course of a combined ECMO-CVVH treatment and justifying the need for a new fluid management system. The innovative design of the new device is expected to achieve either a perfect or controlled negative fluid balance between the ultrafiltrate and replacement fluid flow rates. Perfect fluid balance is achieved by imposing an identical displacement on two pistons, one delivering replacement fluid to the circuit and the other draining ultrafiltrate from the hemofilter. Fluid removal is managed via a second syringe-pump system that reduces the net replacement fluid flow rate with respect to the ultrafiltration flow rate. The novel fluid management system described in this paper is expected to provide an effective method to control precisely fluid flow rates in patients on ECMO. Therefore, this device could potentially improve the efficacy of ECMO therapy and constitute a safe and effective way of reducing fluid overload in patients with cardiorespiratory failure.

High volume peritoneal dialysis vs daily hemodialysis: a randomized, controlled trial in patients with acute kidney injury

There is no consensus in the literature on the best renal replacement therapy (RRT) in acute kidney injury (AKI), with both hemodialysis (HD) and peritoneal dialysis (PD) being used as AKI therapy. However, there are concerns about the inadequacy of PD as well as about the intermittency of HD complicated by hemodynamic instability. Recently, continuous replacement renal therapy (CRRT) have become the most commonly used dialysis method for AKI around the world. A prospective randomized controlled trial was performed to compare the effect of high volume peritoneal dialysis (HVPD) with daily hemodialysis (DHD) on AKI patient survival. A total of 120 patients with acute tubular necrosis (ATN) were assigned to HVPD or DHD in a tertiary-care university hospital. The primary end points were hospital survival rate and renal function recovery, with metabolic control as the secondary end point. Sixty patients were treated with HVPD and 60 with DHD. The HVPD and DHD groups were similar for age (64.2+/-19.8 and 62.5+/-21.2 years), gender (male: 72 and 66%), sepsis (42 and 47%), hemodynamic instability (61 and 63%), severity of AKI (Acute Tubular Necrosis-Index Specific Score (ATN-ISS): 0.68+/-0.2 and 0.66+/-0.2), Acute Physiology, Age, and Chronic Health Evaluation Score (APACHE II) (26.9+/-8.9 and 24.1+/-8.2), pre-dialysis BUN (116.4+/-33.6 and 112.6+/-36.8 mg per 100 ml), and creatinine (5.8+/-1.9 and 5.9+/-1.4 mg per 100 ml). Weekly delivered Kt/V was 3.6+/-0.6 in HVPD and 4.7+/-0.6 in DHD (P<0.01). Metabolic control, mortality rate (58 and 53%), and renal function recovery (28 and 26%) were similar in both groups, whereas HVPD was associated with a significantly shorter time to the recovery of renal function. In conclusion, HVPD and DHD can be considered as alternative forms of RRT in AKI.

N-GAL: diagnosing AKI as soon as possible

Early diagnosis of acute kidney injury (AKI) is often problematic, due to the lack of suitable early biomarkers of renal damage and kidney function. Neutrophil gelatinase-associated lipocalin (NGAL) as an early marker of AKI partially overcomes such limitations and seems to demonstrate that diagnosing AKI in its early stages is possible and useful. Using genomic and protein microarray technology, a series of molecules have been identified as potential markers for AKI; among them NGAL has been demonstrated to rise significantly in patients with AKI but not in the corresponding controls. Furthermore, this rise in NGAL occurs in various studies at 24 to 48 hours before the rise in creatinine is observed. NGAL both in urine and plasma is an excellent early marker of AKI with an area under the receiver operator characteristic curve (AUC) in the range of 0.9. The study of Zappitelli et al. in critically ill children combines for the first time the new RIFLE classification (Risk, Injury, Failure, Loss, End-stage renal disease) of AKI with the validation of NGAL as an early marker of kidney injury. This innovative approach brings a new hope for a timely diagnosis of AKI and thus a timely institution of measures for prevention and protection.