Continuous Arteriovenous Hemofiltration Research Articles

Continuous Renal Replacement Therapy in the Critically Ill Patient: From Garage Technology to Artificial Intelligence.

The history of continuous renal replacement therapy (CRRT) is marked by technological advances linked to improvements in the knowledge of the mechanisms and kinetics of extracorporeal removal of solutes, and the pathophysiology of acute kidney injury (AKI) and other critical illnesses. In the present article, we review the main steps in the history of CRRT, from the discovery of continuous arteriovenous hemofiltration to its evolution into the current treatments and its early use in the treatment of AKI, to the novel sequential extracorporeal therapy. Beyond the technological advances, we describe the development of new medical specialties and a shared nomenclature to support clinicians and researchers in the broad and still evolving field of CRRT.

Technology Innovations in Continuous Kidney Replacement Therapy: The Clinician's Perspective.

Continuous kidney replacement therapy (CKRT) has improved remarkably since its first implementation as continuous arteriovenous hemofiltration in the 1970s. However, when looking at the latest generation of CKRT machines, one could argue that clinical deployment of breakthrough innovations by device manufacturers has slowed in the last decade. Simultaneously, there has been a steady accumulation of clinical knowledge using CKRT as well as a multitude of therapeutic and diagnostic innovations in the dialysis and broader intensive care unit technology fields adaptable to CKRT. These include multiple different anticlotting measures; cloud-computing for optimized treatment prescribing and delivered therapy data collection and analysis; novel blood purification techniques aimed at improving the severe multiorgan dysfunction syndrome; and real-time sensing of blood and/or filter effluent composition. The authors present a view of how CKRT devices and programs could be reimagined incorporating these innovations to achieve specific measurable clinical outcomes with personalized care and improved simplicity, safety, and efficacy of CKRT therapy.

Revisiting Filtration Fraction as an Index of the Risk of Hemofilter Clotting in Continuous Venovenous Hemofiltration.

Hemofilter clotting is a major challenge in continuous venovenous hemofiltration (CVVH). Experts recommend keeping filtration fraction, the fraction of plasma water that is removed by ultrafiltration, below 20% or 30% to avoid clotting ([1][1]). Clotting risk is believed to markedly increase when

The Arterial Access in Continuous Arteriovenous Hemofiltration.

The Arterial Access in Continuous Arteriovenous Hemofiltration.

Evolution of Technology for Continuous Renal Replacement Therapy: Forty Years of Improvement.

Continuous arteriovenous hemofiltration (CAVH) was proposed in 1977 as an alternative treatment for acute renal failure in patients in whom peritoneal dialysis or hemodialysis was clinically or technically precluded. In the mid-1980s, this technique was extended to infants and children. CAVH presented important advantages in the areas of hemodynamic stability, control of circulating volume, and nutritional support. However, there were serious shortcomings such as the need for arterial cannulation and limited solute clearance. These problems were solved by the introduction of continuous arteriovenous hemodiafiltration and continuous arteriovenous hemodialysis, where uremic control could be achieved by increasing countercurrent dialysate flow rates to 1.5 or 2 L/h as necessary, or by venovenous techniques utilizing a double-lumen central venous catheter for vascular access. Thus, continuous venovenous hemofiltration replaced CAVH because of its improved performance and safety. From the initial adoptive technology, specific machines have been designed to permit safe and reliable performance of the therapy. These new machines have progressively undergone a series of technological steps that have resulted in the evolution of highly sophisticated equipment utilized today. A significant number of advances have taken place since the time continuous renal replacement therapy was initiated. In particular, there have been successful experiments with high-volume hemofiltration and high-permeability hemofiltration. The additional and combined use of sorbent has also been tested successfully. Progress has been made in the technology as well as the understanding of the pathophysiology of acute kidney injury. Today, new biomaterials and new devices are available and new frontiers are on the horizon. Although improvements have been made, a lot remains to be done. Critical care nephrology is expected to further evolve in the near future, especially in the area of information and communication technology, utilization of big data and large database registries, biofeedback, and assisted prescription and treatment delivery, with high potential for improvement in morbidity and mortality of the most severely ill patients.

Continuous Renal Replacement Therapy: Forty-year Anniversary.

In 1977 Peter Kramer performed the first CAVH (continuous arteriovenous hemofiltration) treatment in Gottingen, Germany. CAVH soon became a reliable alternative to hemo- or peritoneal dialysis in critically ill patients. The limitations of CAVH spurred new research and the discovery of new treatments such as CVVH and CVVHD (continuous veno-venous hemofiltration and continuous veno-venous hemodialysis). The alliance with industry led to development of new specialized equipment with improved accuracy and performance in delivering continuous renal replacement therapies (CRRTs). Machines and filters have progressively undergone a series of technological steps, reaching a high level of sophistication. The evolution of technology has continued, leading to the development and clinical application of new membranes, new techniques and new treatment modalities. With the progress of technology, the entire field of critical care nephrology moved forward, expanding the areas of application of extracorporeal therapies to cardiac, liver and pulmonary support. A great deal of research made extracorporeal therapies an interesting option for the treatment of sepsis and intoxication and the additional use of sorbents was explored. With the progress in understanding the pathophysiology of acute kidney injury (AKI), new guidelines were developed, driving indications, modalities of prescription, monitoring techniques and quality assurance programs. Information technology and precision medicine have recently contributed to further evolution of CRRT, with the possibility of collecting data in large databases and evaluating policies and practice patterns. This is likely to ultimately result in improved patient care. CRRTs are 40 years old today, but they are still young and full of potential for further evolution.

Evolution of Technology for Continuous Renal Replacement Therapy: Forty Years of Improvements.

Continuous arteriovenous hemofiltration (CAVH) was proposed in 1977 as an alternative treatment for acute renal failure in patients in whom peritoneal dialysis or hemodialysis was clinically or technically precluded. In the mid-1980s, this technique was extended to infants and children. CAVH presented important advantages in the areas of hemodynamic stability, control of circulating volume, and nutritional support. However, there were serious shortcomings such as the need for arterial cannulation and limited solute clearance. These problems were solved by the introduction of continuous arteriovenous hemodiafiltration (CAVHDF) and continuous arteriovenous hemodialysis (CAVHD) where uremic control could be by increasing countercurrent dialysate flow rates to 1.5 or 2 liters/h as necessary, or by venovenous techniques utilizing a double-lumen central venous catheter for vascular access. Thus, continuous venovenous hemofiltration replaced CAVH because of its improved performance and safety. From the initial adoptive technology, specific machines have been designed to permit safe and reliable performance of the therapy. These new machines have progressively undergone a series of technological steps that have resulted in the highly sophisticated equipment utilized today. A significant number of advances have taken place since the beginning of continuous renal replacement therapy. In particular, there have been successful experiments with high-volume hemofiltration and high-permeability hemofiltration. The additional and combined use of sorbent has also been tested successfully. Progress has been made in the technology as well as the understanding of the pathophysiology of acute kidney injury. Today, new biomaterials and new devices are available and new frontiers are on the horizon. Although improvements have been made, a lot remains to be done. Critical care nephrology is expected to further evolve in the near future, especially in the area of information and communication technology, utilization of big data and large database registries, biofeedback, and assisted prescription and treatment delivery, with high potential for improvement in morbidity and mortality of the most severely ill patients.

Validity of low-efficacy continuous renal replacement therapy in critically ill patients.

The 1980s saw the use of continuous arteriovenous hemofiltration whose intensity hemofiltration rate was only 3 or 4 mL kg⁻¹ h⁻¹. With the installation of a blood pump, this dose went up to 8 or 10 mL kg⁻¹ h⁻1, and continued to increase, reaching about 20 mL kg⁻¹ h⁻¹ by the year 2000. Some studies found that a higher dose could be beneficial, and the world rapidly followed the trend, increasing the dose up to 35 mL kg⁻¹ h⁻¹. Then, two randomized control trials, namely the VA/NIH Acute Renal Failure Trial Network study and the RENAL study, came along in succession which changed the Kidney Disease: Improving Global Outcomes (KDIGO) recommendation to 20 to 25 mL kg⁻¹ h⁻¹. However, no good evidence exists to support this. Our recent multicenter retrospective studies from the JSEPTIC CRRT database show that the Japanese continuous renal replacement therapy dose of (14.3 mL kg⁻¹ h⁻¹) does not seem to have worse outcomes when compared with a higher dose.

(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: 20years later.

More than 20years 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. 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. After 20years, 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.

Acute kidney injury in the tropics

Acute kidney injury (AKI) is one of the most challenging problems faced by clinicians in the tropics owing to its fast-changing burden. AKI in the tropics is strikingly different from that in the developed world in terms of etiology and presentation. In addition, there is a stark contrast between well-developed and poor areas in the tropics. The true epidemiological picture of AKI in the tropics is not well understood due to the late presentation of patients to tertiary centers. Infections remain the major culprit in most cases of AKI, with high mortality rates in the tropics. Human immunodeficiency virus–related AKI, related to nephrotoxicity due to antiretroviral therapy, is on the rise. Acute tubular necrosis and thrombotic microangiopathy are the most common mechanisms of AKI. A notable problem in the tropics is the scarcity of resources in health centers to support patients who require critical care due to AKI. This article reviews the unique and contrasting nature of AKI in the tropics and describes its management in each situation.

Using extracorporeal life support to resuscitate adult postcardiotomy cardiogenic shock: Treatment strategies and predictors of short-term and midterm survival

Background Postcardiotomy extracorporeal life support (ECLS) is a resource-demanding therapy with varied results among institutions. An organized protocol was necessary to improve the effectiveness of this therapy. Methods and results A total of 110 patients received ECLS due to refractory postcardiotomy cardiogenic shock between January 2003 and June 2009, and were eligible for inclusion in this retrospective study. Preoperative, perioperative, and postoperative variables were collected, including the European system for cardiac operative risk evaluation (EuroSCORE) and markers of ECLS-related organ injuries. All variables were analyzed for possible associations with mortality in hospital, and after hospital discharge. The mean age, additive EuroSCORE, and left ventricular ejection fraction (LVEF) for all patients was 60 (±14) years, 9 (±6), and 43% (±20%) respectively. Sixty-seven patients were weaned from ECLS and 46 survived to hospital discharge. The mean duration of ECLS support was 143 h (±112 h). Multivariate analysis revealed that an age of >60 years, a necessity for postoperative continuous arteriovenous hemofiltration, a maximal serum total bilirubin >6 mg/dL, and a need for ECLS support for >110 h were independent predictors of in-hospital mortality. In addition, persistent heart failure with LVEF <30% was an independent predictor of mortality after hospital discharge. A risk-predicting score for in-hospital mortality associated with postcardiotomy ECLS was developed for clinical application. Conclusion Based on the abovementioned findings, a comprehensive protocol for postcardiotomy ECLS was designed. The primary objective was to achieve adequate hemodynamics within the first 24 h of initiating ECLS. Other objectives of the protocol included a consistent approach to safe anticoagulation while on ECLS, a process to make decisions within 7 days of initiating ECLS, and patient follow-up after hospital discharge.

Antithrombogenicity of polyacrylonitrile-polyethyleneoxide hollow fiber membrane developed for designing an antithrombogenic continuous ultrafiltration system.

To develop a continuous arteriovenous hemofiltration (CAVH) system, which does not need systemic anticoagulation, for patients of acute renal failure having bleeding tendencies, a totally antithrombogenic continuous ultrafiltration system (ACUS) was designed, which consists of an antithrombogenic polyacrylonitrile-polyethyleneoxide (PAN-PEO) hollow fiber membrane and ionically heparin-bound catheter, tubing, and module header. Antithrombogenicity of PAN-PEO membrane, which occupies more than 90% of total inner surface area of ACUS, was considered to be due to highly concentrated PEO near the inner surface of the membrane and the finely dispersed (less than 500 A) microstructure of the inner surface. ACUS was applied to 24 patients without systemic anticoagulation, and one filter worked for an average of 32 h without deteriorating their bleeding tendencies. Any significant changes in major parameters of biocompatibility during those treatments were not observed. More than 200 ml/h of ultrafiltrate was obtained even under very low mean blood pressure, less than 70 mm Hg. Based upon these results, ACUS was concluded to be suitable for mild and sustained treatment to control fluid and electrolyte balance in patients of acute renal failure with bleeding complications.

Tandem plasmapheresis and haemodialysis as a safe procedure in 82 patients with immune-mediated disease

A number of medical, mostly immune-mediated conditions call for a combination therapy consisting of plasmapheresis and haemodialysis. While the two treatments are most commonly applied separately, we describe here the technical details of providing a combined 'tandem' treatment. Method. The components of a dialyzer (polysulfon membrane) and plasma filter are serially connected by a continuous arteriovenous haemofiltration (CAVH) system. In an extracorporeal circulation, using a blood pump the patient's blood is led first to the plasma filter and then into the dialyzer. The substituate connection is located behind the plasma filter and before the dialyzer. At the beginning it is obligatory to carry out an inspection of tubing system leakages. Afterwards, the system is flushed with a heparinized (5000 IE) sodium chloride solution that is removed thereafter. During the treatment, a blood flow of 150-200 ml/min is possible. In each case, the plasmafiltration and the ultrafiltration should not exceed 25% of the blood flow. The whole time, an intermittent check of blood pressure and heart rate is necessary. The total procedure does not take longer than a routine haemodialysis (3-4 h). In 82 patients we performed 483 tandem treatments during the last 16 years. None of the patients had volume disturbances caused by plasma shifts and derangements of electrolytes and acid-base balance were immediately equalized. There were no episodes of hypotension or bleeding. Back-filtration did not occur. Providing both haemodialysis and plasmapheresis at the same time reduces treatment time and thus, overall cost of the treatment. This retrospective analysis shows the tandem treatment to be safe and effective.

Antithrombin III substitution in dialysis-dependent renal insufficiency

Haemodialysis had become impossible or possible only using high doses of heparin in 20 patients with dialysis-dependent renal insufficiency due to lowering of antithrombin III (AT III). In order to assess the value of AT III substitution for effective heparin treatment and concomitant diminution of the danger of haemorrhage AT III substitution was done in these patients. Six patients. Six patients with acute renal failure and disseminated intravascular coagulation were able to undergo dialysis using only 750-1000 IU heparin/h after normalisation of AT III without complications. In 3 patients thrombosing of the extracorporeal system had occurred despite increasing doses of heparin; only after 1500 U AT III subsequent haemodialysis could be performed without thromboses. Dialysis was performed with continuous substitution of the AT III-heparin-complex in 6 patients prone to haemorrhage. 250-500 U of AT III-heparin-complex were sufficient and proved as safe and well manageable possibility of minimal anticoagulation. In 5 patients repeated thrombosing of the haemofilter per day had occurred during continuous arteriovenous haemofiltration. After AT III administration haemofilters could be left in situ for 18-46 hours.

Hybrid Treatment for Complex Aortic Problems Combining Surgery and Stenting in the Integrated Operating Theater

Conventional surgical treatment of complex aortic pathologies involving several thoracoabdominal aortic segments necessitates extended incisions or subsequent surgeries, resulting in significant mortality and morbidity rates. The combination of surgery and simultaneous stenting in the operating theater may reduce the surgical trauma. A total of nine patients (62 +/- 10 years, range 44-70) underwent a combined surgical and endovascular treatment of thoracic or thoracoabdominal aortic aneurysms or chronic dissection. Five patients were treated with viscero-renal artery translocation followed by transfemoral stenting of the entire thoracoabdominal aorta. Two patients underwent debranching of the supraaortic vessels followed by immediate transfemoral stenting of the aortic arch, and two patients with a history of an ascending aortic aneurysm repair were treated with open surgical debranching of the supraaortic trunks and repair of the ascending aorta and aortic arch with elephant trunk technique. Preoperatively, magnetic resonance imaging was used to check supraaortic and intracranial vessels as well as the completeness of the Circle of Willisi prior to arch stenting and/or supraaortic vessel surgery. Cerebrospinal fluid drainage and induced mild hypertension have been used for one-step thoracoabdominal aortic stenting. Thirty-day mortality rate and incidence of paraplegia was 0%. There was a single reversible perioperative stroke after aortic arch stenting. One patient required temporary renal replacement therapy using continuous arterio-venous hemofiltration. There was one early reoperation at the superior mesenteric artery after viscero-renal translocation. Four type I endoleaks occurred in three patients requiring two interventions. All patients have been discharged to home. The innovative combination of simultaneous conventional surgery and stenting reduces the operative burden for patients with complex aortic pathologies involving several segments of the thoracic and thoracoabdominal aorta. Arch debranching and viscero-renal artery translocation may avoid the use of thoracoabdominal incisions, cardiopulmonary bypass techniques, deep hypothermia, and circulatory arrest.

Neonatal Hemodialysis and Continuous Renal Replacement Therapy

After completing this article, readers should be able to: 1. Describe catheters, dialyzers, and blood lines in hemodialysis for neonates. 2. Explain the blood prime and hemodialysis prescription in hemodialysis for neonates. 3. List potential complications of hemodialysis for neonates. 4. Identify the types of continuous renal replacement therapy (CRRT) in neonates. 5. Explain the dialysis prescription and anticoagulation options for CRRT in neonates. 6. List potential complications of CRRT in neonates. Since the mid-1980s, when dialysis manufacturers began making dialyzers and blood circuit paths that required smaller extracorporeal volumes, hemodialysis has been used successfully to manage renal failure in neonates and infants. Compared with peritoneal dialysis (PD), which is analogous to the “family sedan” in the world of dialysis (slower, more predictable, easier to operate), hemodialysis is the “race car.” Hemodialysis is capable of removing fluids and solutes much more rapidly than is PD. Unlike PD, hemodialysis uses catheters that access the intravascular space directly. Despite the advantages of hemodialysis, the process in neonates is technically more challenging than PD due to the very attributes that make it so effective. Rapid removal of intravascular fluids, exceeding the rate of refill from the extravascular space, causes problems with hypotension due to direct reduction in intravascular volume. Similarly, rapid rates of solute clearance can cause problems with increased intracranial pressure. Catheter placement and maintenance of catheter function can constitute a significant obstacle to hemodialysis. Hemofiltration is very similar to hemodialysis in that patient blood is circulated through an artificial kidney. However, hemofiltration differs from hemodialysis in three significant aspects. First, the hemofilter has larger pore sizes than the standard dialyzer, which allows for excellent fluid removal, even with low blood flow rates, and better larger molecule clearance. Second, hemofiltration runs continuously without the continuous presence of a dialysis nurse. Third, typical hemofiltration uses a pre- or postdilution …

Plasma exchange as rescue therapy in multiple organ failure including acute renal failure.

To describe the outcome of using a rescue therapy including plasma exchange given to patients with a progressive acute disseminated intravascular coagulation and multiple organ dysfunction syndrome. Retrospective study. University and county hospital. Included were 76 consecutive patients (41 men and 35 women) treated with plasma exchange as rescue therapy besides optimal conventional therapy during a progressive course of disseminated intravascular coagulation and multiple organ dysfunction syndrome, including acute renal failure. Of the 76 patients, 66% needed dialysis. The distribution was hemodialysis in 76%, continuous arteriovenous hemofiltration in 36%, continuous venovenous hemodialysis in 12%, and peritoneal dialysis in 24%. The median organ-failure score was 5 (range, 1-6). Seventy-two percent required mechanical ventilation; septic shock was present in 88%. The median septic shock score was 4 (range, 2-4). Nine patients had another reason than sepsis for the multiple organ dysfunction syndrome. Plasma exchange (centrifugation technique) was performed until disseminated intravascular coagulation was reversed (median, two times; range, 1-14). Besides antibiotics and fluid administration, most patients received heparin or low molecular weight heparin (77%), steroids (87%), and inotropes (88%). More than one vasoactive drug was used in 57% of the patients. Eighty-two percent of the patients survived and could leave the hospital. The previously observed survival rates by others for this category of patients would be <20%, and thus, the outcome in this study is significantly better. Plasma exchange using plasma as replacement may, in addition to conventional intensive care, help to reverse severe progressive disseminated intravascular coagulation and multiple organ dysfunction syndrome and improve survival.

Neurodevelopmental outcome of infants supported with extracorporeal membrane oxygenation after cardiac surgery.

To evaluate the long-term neurodevelopmental outcome of infants who underwent cardiac surgery and required extracorporeal membrane oxygenation (ECMO) support, and to examine variables that predict death or disability in these patients. We studied all infants who had congenital heart disease and were supported postoperatively with ECMO from 1990 to 2001 at our institution (n = 53). Medical records were reviewed retrospectively to obtain clinical variables. Neurologic and age-appropriate developmental examinations occurred at ages 1, 1.5, 2.5, and 4.5 years. Median age at follow-up was 55 months (9-101). Cognitive outcome was defined as suspect when scores were between 1 and 2 SD below the mean for age and abnormal when scores were >2 SD below mean for age. Neuromotor outcome was defined as suspect when the patient manifested clumsiness, tremor, or mild tone and reflex changes without functional limitations, and abnormal when there were functional limitations. In-hospital survival was 17 (32%) of 53. Of survivors, 14 (88%) of 16 are living and 1 patient was lost to follow-up. Of the 53 patients, 7 survived completely intact (13%). Seven (50%) of 14 patients had a normal cognitive outcome, 3 (21%) had a suspect cognitive outcome, and 4 (29%) were abnormal. Ten (72%) of 14 patients had a normal neuromotor outcome, 1 (7%) patient had a suspect neuromotor outcome, and 3 (21%) were abnormal. No survivor with an aortic cross-clamp time >40 minutes had a normal cognitive outcome. Nonsurvivors were more likely than survivors to have had cardiac arrest as an indication for ECMO (31% vs 6%), to have had a longer aortic cross-clamp time (mean 73 minutes vs 32 minutes), and to have required continuous arteriovenous hemofiltration (78% vs 35%). The age and weight at cannulation, gender, cardiac diagnosis, interval from surgery to ECMO, cardiopulmonary bypass time, diagnosis of sepsis or mediastinitis, and duration of ECMO were not significantly associated with survival. Although mortality was 68% in infants who had congenital heart disease and were treated with ECMO postoperatively, of those who survive to hospital discharge, 75% have a normal neuromotor outcome and 50% have a normal cognitive outcome. These high rates of mortality and disability suggest that increased attention be paid to neuroprotection in these complex disorders.

Continuous renal replacement therapy: opinions and evidence.

Continuous arteriovenous haemofiltration (CAVH) is the first example of continuous renal replacement therapy (CRRT). CAVH was first applied for the treatment of diuretic unresponsive fluid overload. Subsequently, CRRT has undergone a remarkable growth, and it is now performed with pump technology (CVVH) and via double-lumen central venous catheters. In many intensive care units, especially in Australia and in Europe, CRRT has become the dominant, if not exclusive, form of artificial renal support. Continuous haemofiltration is now used beyond the original indications of blood purification, for the treatment of certain drug intoxications, for severe cardiac failure, for volume control during, after cardiopulmonary bypass, and to decrease the toxicity of chemotherapy. Furthermore, there is strong ongoing research into its role or that of derived techniques as possible adjuvant therapies during severe sepsis. Despite its large use, the current state of CRRT is surrounded by some controversies, and an effort should be made to give a dispassionate distillation of the literature for a final common definition of what is based on opinions and what carries sufficient evidence.